Actual source code: snes.c

petsc-master 2020-08-05
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  1:  #include <petsc/private/snesimpl.h>
  2:  #include <petscdmshell.h>
  3:  #include <petscdraw.h>
  4:  #include <petscds.h>
  5:  #include <petscdmadaptor.h>
  6:  #include <petscconvest.h>

  8: PetscBool         SNESRegisterAllCalled = PETSC_FALSE;
  9: PetscFunctionList SNESList              = NULL;

 11: /* Logging support */
 12: PetscClassId  SNES_CLASSID, DMSNES_CLASSID;
 13: PetscLogEvent SNES_Solve, SNES_Setup, SNES_FunctionEval, SNES_JacobianEval, SNES_NGSEval, SNES_NGSFuncEval, SNES_NPCSolve, SNES_ObjectiveEval;

 15: /*@
 16:    SNESSetErrorIfNotConverged - Causes SNESSolve() to generate an error if the solver has not converged.

 18:    Logically Collective on SNES

 20:    Input Parameters:
 21: +  snes - iterative context obtained from SNESCreate()
 22: -  flg - PETSC_TRUE indicates you want the error generated

 24:    Options database keys:
 25: .  -snes_error_if_not_converged : this takes an optional truth value (0/1/no/yes/true/false)

 27:    Level: intermediate

 29:    Notes:
 30:     Normally PETSc continues if a linear solver fails to converge, you can call SNESGetConvergedReason() after a SNESSolve()
 31:     to determine if it has converged.

 33: .seealso: SNESGetErrorIfNotConverged(), KSPGetErrorIfNotConverged(), KSPSetErrorIFNotConverged()
 34: @*/
 35: PetscErrorCode  SNESSetErrorIfNotConverged(SNES snes,PetscBool flg)
 36: {
 40:   snes->errorifnotconverged = flg;
 41:   return(0);
 42: }

 44: /*@
 45:    SNESGetErrorIfNotConverged - Will SNESSolve() generate an error if the solver does not converge?

 47:    Not Collective

 49:    Input Parameter:
 50: .  snes - iterative context obtained from SNESCreate()

 52:    Output Parameter:
 53: .  flag - PETSC_TRUE if it will generate an error, else PETSC_FALSE

 55:    Level: intermediate

 57: .seealso:  SNESSetErrorIfNotConverged(), KSPGetErrorIfNotConverged(), KSPSetErrorIFNotConverged()
 58: @*/
 59: PetscErrorCode  SNESGetErrorIfNotConverged(SNES snes,PetscBool  *flag)
 60: {
 64:   *flag = snes->errorifnotconverged;
 65:   return(0);
 66: }

 68: /*@
 69:     SNESSetAlwaysComputesFinalResidual - does the SNES always compute the residual at the final solution?

 71:    Logically Collective on SNES

 73:     Input Parameters:
 74: +   snes - the shell SNES
 75: -   flg - is the residual computed?

 77:    Level: advanced

 79: .seealso: SNESGetAlwaysComputesFinalResidual()
 80: @*/
 81: PetscErrorCode  SNESSetAlwaysComputesFinalResidual(SNES snes, PetscBool flg)
 82: {
 85:   snes->alwayscomputesfinalresidual = flg;
 86:   return(0);
 87: }

 89: /*@
 90:     SNESGetAlwaysComputesFinalResidual - does the SNES always compute the residual at the final solution?

 92:    Logically Collective on SNES

 94:     Input Parameter:
 95: .   snes - the shell SNES

 97:     Output Parameter:
 98: .   flg - is the residual computed?

100:    Level: advanced

102: .seealso: SNESSetAlwaysComputesFinalResidual()
103: @*/
104: PetscErrorCode  SNESGetAlwaysComputesFinalResidual(SNES snes, PetscBool *flg)
105: {
108:   *flg = snes->alwayscomputesfinalresidual;
109:   return(0);
110: }

112: /*@
113:    SNESSetFunctionDomainError - tells SNES that the input vector to your SNESFunction is not
114:      in the functions domain. For example, negative pressure.

116:    Logically Collective on SNES

118:    Input Parameters:
119: .  snes - the SNES context

121:    Level: advanced

123: .seealso: SNESCreate(), SNESSetFunction(), SNESFunction
124: @*/
125: PetscErrorCode  SNESSetFunctionDomainError(SNES snes)
126: {
129:   if (snes->errorifnotconverged) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"User code indicates input vector is not in the function domain");
130:   snes->domainerror = PETSC_TRUE;
131:   return(0);
132: }

134: /*@
135:    SNESSetJacobianDomainError - tells SNES that computeJacobian does not make sense any more. For example there is a negative element transformation.

137:    Logically Collective on SNES

139:    Input Parameters:
140: .  snes - the SNES context

142:    Level: advanced

144: .seealso: SNESCreate(), SNESSetFunction(), SNESFunction(), SNESSetFunctionDomainError()
145: @*/
146: PetscErrorCode SNESSetJacobianDomainError(SNES snes)
147: {
150:   if (snes->errorifnotconverged) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"User code indicates computeJacobian does not make sense");
151:   snes->jacobiandomainerror = PETSC_TRUE;
152:   return(0);
153: }

155: /*@
156:    SNESSetCheckJacobianDomainError - if or not to check jacobian domain error after each Jacobian evaluation. By default, we check Jacobian domain error
157:    in the debug mode, and do not check it in the optimized mode.

159:    Logically Collective on SNES

161:    Input Parameters:
162: +  snes - the SNES context
163: -  flg  - indicates if or not to check jacobian domain error after each Jacobian evaluation

165:    Level: advanced

167: .seealso: SNESCreate(), SNESSetFunction(), SNESFunction(), SNESSetFunctionDomainError(), SNESGetCheckJacobianDomainError()
168: @*/
169: PetscErrorCode SNESSetCheckJacobianDomainError(SNES snes, PetscBool flg)
170: {
173:   snes->checkjacdomainerror = flg;
174:   return(0);
175: }

177: /*@
178:    SNESGetCheckJacobianDomainError - Get an indicator whether or not we are checking Jacobian domain errors after each Jacobian evaluation.

180:    Logically Collective on SNES

182:    Input Parameters:
183: .  snes - the SNES context

185:    Output Parameters:
186: .  flg  - PETSC_FALSE indicates that we don't check jacobian domain errors after each Jacobian evaluation

188:    Level: advanced

190: .seealso: SNESCreate(), SNESSetFunction(), SNESFunction(), SNESSetFunctionDomainError(), SNESSetCheckJacobianDomainError()
191: @*/
192: PetscErrorCode SNESGetCheckJacobianDomainError(SNES snes, PetscBool *flg)
193: {
197:   *flg = snes->checkjacdomainerror;
198:   return(0);
199: }

201: /*@
202:    SNESGetFunctionDomainError - Gets the status of the domain error after a call to SNESComputeFunction;

204:    Logically Collective on SNES

206:    Input Parameters:
207: .  snes - the SNES context

209:    Output Parameters:
210: .  domainerror - Set to PETSC_TRUE if there's a domain error; PETSC_FALSE otherwise.

212:    Level: advanced

214: .seealso: SNESSetFunctionDomainError(), SNESComputeFunction()
215: @*/
216: PetscErrorCode  SNESGetFunctionDomainError(SNES snes, PetscBool *domainerror)
217: {
221:   *domainerror = snes->domainerror;
222:   return(0);
223: }

225: /*@
226:    SNESGetJacobianDomainError - Gets the status of the Jacobian domain error after a call to SNESComputeJacobian;

228:    Logically Collective on SNES

230:    Input Parameters:
231: .  snes - the SNES context

233:    Output Parameters:
234: .  domainerror - Set to PETSC_TRUE if there's a jacobian domain error; PETSC_FALSE otherwise.

236:    Level: advanced

238: .seealso: SNESSetFunctionDomainError(), SNESComputeFunction(),SNESGetFunctionDomainError()
239: @*/
240: PetscErrorCode SNESGetJacobianDomainError(SNES snes, PetscBool *domainerror)
241: {
245:   *domainerror = snes->jacobiandomainerror;
246:   return(0);
247: }

249: /*@C
250:   SNESLoad - Loads a SNES that has been stored in binary  with SNESView().

252:   Collective on PetscViewer

254:   Input Parameters:
255: + newdm - the newly loaded SNES, this needs to have been created with SNESCreate() or
256:            some related function before a call to SNESLoad().
257: - viewer - binary file viewer, obtained from PetscViewerBinaryOpen()

259:    Level: intermediate

261:   Notes:
262:    The type is determined by the data in the file, any type set into the SNES before this call is ignored.

264:   Notes for advanced users:
265:   Most users should not need to know the details of the binary storage
266:   format, since SNESLoad() and TSView() completely hide these details.
267:   But for anyone who's interested, the standard binary matrix storage
268:   format is
269: .vb
270:      has not yet been determined
271: .ve

273: .seealso: PetscViewerBinaryOpen(), SNESView(), MatLoad(), VecLoad()
274: @*/
275: PetscErrorCode  SNESLoad(SNES snes, PetscViewer viewer)
276: {
278:   PetscBool      isbinary;
279:   PetscInt       classid;
280:   char           type[256];
281:   KSP            ksp;
282:   DM             dm;
283:   DMSNES         dmsnes;

288:   PetscObjectTypeCompare((PetscObject)viewer,PETSCVIEWERBINARY,&isbinary);
289:   if (!isbinary) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_WRONG,"Invalid viewer; open viewer with PetscViewerBinaryOpen()");

291:   PetscViewerBinaryRead(viewer,&classid,1,NULL,PETSC_INT);
292:   if (classid != SNES_FILE_CLASSID) SETERRQ(PetscObjectComm((PetscObject)snes),PETSC_ERR_ARG_WRONG,"Not SNES next in file");
293:   PetscViewerBinaryRead(viewer,type,256,NULL,PETSC_CHAR);
294:   SNESSetType(snes, type);
295:   if (snes->ops->load) {
296:     (*snes->ops->load)(snes,viewer);
297:   }
298:   SNESGetDM(snes,&dm);
299:   DMGetDMSNES(dm,&dmsnes);
300:   DMSNESLoad(dmsnes,viewer);
301:   SNESGetKSP(snes,&ksp);
302:   KSPLoad(ksp,viewer);
303:   return(0);
304: }

306:  #include <petscdraw.h>
307: #if defined(PETSC_HAVE_SAWS)
308:  #include <petscviewersaws.h>
309: #endif

311: /*@C
312:    SNESViewFromOptions - View from Options

314:    Collective on SNES

316:    Input Parameters:
317: +  A - the Section 1.5 Writing Application Codes with PETSc ordering context
318: .  obj - Optional object
319: -  name - command line option

321:    Level: intermediate
322: .seealso:  SNES, SNESView, PetscObjectViewFromOptions(), SNESCreate()
323: @*/
324: PetscErrorCode  SNESViewFromOptions(SNES A,PetscObject obj,const char name[])
325: {

330:   PetscObjectViewFromOptions((PetscObject)A,obj,name);
331:   return(0);
332: }

334: PETSC_EXTERN PetscErrorCode SNESComputeJacobian_DMDA(SNES,Vec,Mat,Mat,void*);

336: /*@C
337:    SNESView - Prints the SNES data structure.

339:    Collective on SNES

341:    Input Parameters:
342: +  SNES - the SNES context
343: -  viewer - visualization context

345:    Options Database Key:
346: .  -snes_view - Calls SNESView() at end of SNESSolve()

348:    Notes:
349:    The available visualization contexts include
350: +     PETSC_VIEWER_STDOUT_SELF - standard output (default)
351: -     PETSC_VIEWER_STDOUT_WORLD - synchronized standard
352:          output where only the first processor opens
353:          the file.  All other processors send their
354:          data to the first processor to print.

356:    The user can open an alternative visualization context with
357:    PetscViewerASCIIOpen() - output to a specified file.

359:    Level: beginner

361: .seealso: PetscViewerASCIIOpen()
362: @*/
363: PetscErrorCode  SNESView(SNES snes,PetscViewer viewer)
364: {
365:   SNESKSPEW      *kctx;
367:   KSP            ksp;
368:   SNESLineSearch linesearch;
369:   PetscBool      iascii,isstring,isbinary,isdraw;
370:   DMSNES         dmsnes;
371: #if defined(PETSC_HAVE_SAWS)
372:   PetscBool      issaws;
373: #endif

377:   if (!viewer) {
378:     PetscViewerASCIIGetStdout(PetscObjectComm((PetscObject)snes),&viewer);
379:   }

383:   PetscObjectTypeCompare((PetscObject)viewer,PETSCVIEWERASCII,&iascii);
384:   PetscObjectTypeCompare((PetscObject)viewer,PETSCVIEWERSTRING,&isstring);
385:   PetscObjectTypeCompare((PetscObject)viewer,PETSCVIEWERBINARY,&isbinary);
386:   PetscObjectTypeCompare((PetscObject)viewer,PETSCVIEWERDRAW,&isdraw);
387: #if defined(PETSC_HAVE_SAWS)
388:   PetscObjectTypeCompare((PetscObject)viewer,PETSCVIEWERSAWS,&issaws);
389: #endif
390:   if (iascii) {
391:     SNESNormSchedule normschedule;
392:     DM               dm;
393:     PetscErrorCode   (*cJ)(SNES,Vec,Mat,Mat,void*);
394:     void             *ctx;
395:     const char       *pre = "";

397:     PetscObjectPrintClassNamePrefixType((PetscObject)snes,viewer);
398:     if (!snes->setupcalled) {
399:       PetscViewerASCIIPrintf(viewer,"  SNES has not been set up so information may be incomplete\n");
400:     }
401:     if (snes->ops->view) {
402:       PetscViewerASCIIPushTab(viewer);
403:       (*snes->ops->view)(snes,viewer);
404:       PetscViewerASCIIPopTab(viewer);
405:     }
406:     PetscViewerASCIIPrintf(viewer,"  maximum iterations=%D, maximum function evaluations=%D\n",snes->max_its,snes->max_funcs);
407:     PetscViewerASCIIPrintf(viewer,"  tolerances: relative=%g, absolute=%g, solution=%g\n",(double)snes->rtol,(double)snes->abstol,(double)snes->stol);
408:     if (snes->usesksp) {
409:       PetscViewerASCIIPrintf(viewer,"  total number of linear solver iterations=%D\n",snes->linear_its);
410:     }
411:     PetscViewerASCIIPrintf(viewer,"  total number of function evaluations=%D\n",snes->nfuncs);
412:     SNESGetNormSchedule(snes, &normschedule);
413:     if (normschedule > 0) {PetscViewerASCIIPrintf(viewer,"  norm schedule %s\n",SNESNormSchedules[normschedule]);}
414:     if (snes->gridsequence) {
415:       PetscViewerASCIIPrintf(viewer,"  total number of grid sequence refinements=%D\n",snes->gridsequence);
416:     }
417:     if (snes->ksp_ewconv) {
418:       kctx = (SNESKSPEW*)snes->kspconvctx;
419:       if (kctx) {
420:         PetscViewerASCIIPrintf(viewer,"  Eisenstat-Walker computation of KSP relative tolerance (version %D)\n",kctx->version);
421:         PetscViewerASCIIPrintf(viewer,"    rtol_0=%g, rtol_max=%g, threshold=%g\n",(double)kctx->rtol_0,(double)kctx->rtol_max,(double)kctx->threshold);
422:         PetscViewerASCIIPrintf(viewer,"    gamma=%g, alpha=%g, alpha2=%g\n",(double)kctx->gamma,(double)kctx->alpha,(double)kctx->alpha2);
423:       }
424:     }
425:     if (snes->lagpreconditioner == -1) {
426:       PetscViewerASCIIPrintf(viewer,"  Preconditioned is never rebuilt\n");
427:     } else if (snes->lagpreconditioner > 1) {
428:       PetscViewerASCIIPrintf(viewer,"  Preconditioned is rebuilt every %D new Jacobians\n",snes->lagpreconditioner);
429:     }
430:     if (snes->lagjacobian == -1) {
431:       PetscViewerASCIIPrintf(viewer,"  Jacobian is never rebuilt\n");
432:     } else if (snes->lagjacobian > 1) {
433:       PetscViewerASCIIPrintf(viewer,"  Jacobian is rebuilt every %D SNES iterations\n",snes->lagjacobian);
434:     }
435:     SNESGetDM(snes,&dm);
436:     DMSNESGetJacobian(dm,&cJ,&ctx);
437:     if (snes->mf_operator) {
438:       PetscViewerASCIIPrintf(viewer,"  Jacobian is applied matrix-free with differencing\n");
439:       pre  = "Preconditioning ";
440:     }
441:     if (cJ == SNESComputeJacobianDefault) {
442:       PetscViewerASCIIPrintf(viewer,"  %sJacobian is built using finite differences one column at a time\n",pre);
443:     } else if (cJ == SNESComputeJacobianDefaultColor) {
444:       PetscViewerASCIIPrintf(viewer,"  %sJacobian is built using finite differences with coloring\n",pre);
445:     /* it slightly breaks data encapsulation for access the DMDA information directly */
446:     } else if (cJ == SNESComputeJacobian_DMDA) {
447:       MatFDColoring fdcoloring;
448:       PetscObjectQuery((PetscObject)dm,"DMDASNES_FDCOLORING",(PetscObject*)&fdcoloring);
449:       if (fdcoloring) {
450:         PetscViewerASCIIPrintf(viewer,"  %sJacobian is built using colored finite differences on a DMDA\n",pre);
451:       } else {
452:         PetscViewerASCIIPrintf(viewer,"  %sJacobian is built using a DMDA local Jacobian\n",pre);
453:       }
454:     } else if (snes->mf) {
455:       PetscViewerASCIIPrintf(viewer,"  Jacobian is applied matrix-free with differencing, no explict Jacobian\n");
456:     }
457:   } else if (isstring) {
458:     const char *type;
459:     SNESGetType(snes,&type);
460:     PetscViewerStringSPrintf(viewer," SNESType: %-7.7s",type);
461:     if (snes->ops->view) {(*snes->ops->view)(snes,viewer);}
462:   } else if (isbinary) {
463:     PetscInt    classid = SNES_FILE_CLASSID;
464:     MPI_Comm    comm;
465:     PetscMPIInt rank;
466:     char        type[256];

468:     PetscObjectGetComm((PetscObject)snes,&comm);
469:     MPI_Comm_rank(comm,&rank);
470:     if (!rank) {
471:       PetscViewerBinaryWrite(viewer,&classid,1,PETSC_INT);
472:       PetscStrncpy(type,((PetscObject)snes)->type_name,sizeof(type));
473:       PetscViewerBinaryWrite(viewer,type,sizeof(type),PETSC_CHAR);
474:     }
475:     if (snes->ops->view) {
476:       (*snes->ops->view)(snes,viewer);
477:     }
478:   } else if (isdraw) {
479:     PetscDraw draw;
480:     char      str[36];
481:     PetscReal x,y,bottom,h;

483:     PetscViewerDrawGetDraw(viewer,0,&draw);
484:     PetscDrawGetCurrentPoint(draw,&x,&y);
485:     PetscStrncpy(str,"SNES: ",sizeof(str));
486:     PetscStrlcat(str,((PetscObject)snes)->type_name,sizeof(str));
487:     PetscDrawStringBoxed(draw,x,y,PETSC_DRAW_BLUE,PETSC_DRAW_BLACK,str,NULL,&h);
488:     bottom = y - h;
489:     PetscDrawPushCurrentPoint(draw,x,bottom);
490:     if (snes->ops->view) {
491:       (*snes->ops->view)(snes,viewer);
492:     }
493: #if defined(PETSC_HAVE_SAWS)
494:   } else if (issaws) {
495:     PetscMPIInt rank;
496:     const char *name;

498:     PetscObjectGetName((PetscObject)snes,&name);
499:     MPI_Comm_rank(PETSC_COMM_WORLD,&rank);
500:     if (!((PetscObject)snes)->amsmem && !rank) {
501:       char       dir[1024];

503:       PetscObjectViewSAWs((PetscObject)snes,viewer);
504:       PetscSNPrintf(dir,1024,"/PETSc/Objects/%s/its",name);
505:       PetscStackCallSAWs(SAWs_Register,(dir,&snes->iter,1,SAWs_READ,SAWs_INT));
506:       if (!snes->conv_hist) {
507:         SNESSetConvergenceHistory(snes,NULL,NULL,PETSC_DECIDE,PETSC_TRUE);
508:       }
509:       PetscSNPrintf(dir,1024,"/PETSc/Objects/%s/conv_hist",name);
510:       PetscStackCallSAWs(SAWs_Register,(dir,snes->conv_hist,10,SAWs_READ,SAWs_DOUBLE));
511:     }
512: #endif
513:   }
514:   if (snes->linesearch) {
515:     SNESGetLineSearch(snes, &linesearch);
516:     PetscViewerASCIIPushTab(viewer);
517:     SNESLineSearchView(linesearch, viewer);
518:     PetscViewerASCIIPopTab(viewer);
519:   }
520:   if (snes->npc && snes->usesnpc) {
521:     PetscViewerASCIIPushTab(viewer);
522:     SNESView(snes->npc, viewer);
523:     PetscViewerASCIIPopTab(viewer);
524:   }
525:   PetscViewerASCIIPushTab(viewer);
526:   DMGetDMSNES(snes->dm,&dmsnes);
527:   DMSNESView(dmsnes, viewer);
528:   PetscViewerASCIIPopTab(viewer);
529:   if (snes->usesksp) {
530:     SNESGetKSP(snes,&ksp);
531:     PetscViewerASCIIPushTab(viewer);
532:     KSPView(ksp,viewer);
533:     PetscViewerASCIIPopTab(viewer);
534:   }
535:   if (isdraw) {
536:     PetscDraw draw;
537:     PetscViewerDrawGetDraw(viewer,0,&draw);
538:     PetscDrawPopCurrentPoint(draw);
539:   }
540:   return(0);
541: }

543: /*
544:   We retain a list of functions that also take SNES command
545:   line options. These are called at the end SNESSetFromOptions()
546: */
547: #define MAXSETFROMOPTIONS 5
548: static PetscInt numberofsetfromoptions;
549: static PetscErrorCode (*othersetfromoptions[MAXSETFROMOPTIONS])(SNES);

551: /*@C
552:   SNESAddOptionsChecker - Adds an additional function to check for SNES options.

554:   Not Collective

556:   Input Parameter:
557: . snescheck - function that checks for options

559:   Level: developer

561: .seealso: SNESSetFromOptions()
562: @*/
563: PetscErrorCode  SNESAddOptionsChecker(PetscErrorCode (*snescheck)(SNES))
564: {
566:   if (numberofsetfromoptions >= MAXSETFROMOPTIONS) SETERRQ1(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE, "Too many options checkers, only %D allowed", MAXSETFROMOPTIONS);
567:   othersetfromoptions[numberofsetfromoptions++] = snescheck;
568:   return(0);
569: }

571: PETSC_INTERN PetscErrorCode SNESDefaultMatrixFreeCreate2(SNES,Vec,Mat*);

573: static PetscErrorCode SNESSetUpMatrixFree_Private(SNES snes, PetscBool hasOperator, PetscInt version)
574: {
575:   Mat            J;
577:   MatNullSpace   nullsp;


582:   if (!snes->vec_func && (snes->jacobian || snes->jacobian_pre)) {
583:     Mat A = snes->jacobian, B = snes->jacobian_pre;
584:     MatCreateVecs(A ? A : B, NULL,&snes->vec_func);
585:   }

587:   if (version == 1) {
588:     MatCreateSNESMF(snes,&J);
589:     MatMFFDSetOptionsPrefix(J,((PetscObject)snes)->prefix);
590:     MatSetFromOptions(J);
591:   } else if (version == 2) {
592:     if (!snes->vec_func) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_WRONGSTATE,"SNESSetFunction() must be called first");
593: #if !defined(PETSC_USE_COMPLEX) && !defined(PETSC_USE_REAL_SINGLE) && !defined(PETSC_USE_REAL___FLOAT128) && !defined(PETSC_USE_REAL___FP16)
594:     SNESDefaultMatrixFreeCreate2(snes,snes->vec_func,&J);
595: #else
596:     SETERRQ(PETSC_COMM_SELF,PETSC_ERR_SUP, "matrix-free operator rutines (version 2)");
597: #endif
598:   } else SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE, "matrix-free operator rutines, only version 1 and 2");

600:   /* attach any user provided null space that was on Amat to the newly created matrix free matrix */
601:   if (snes->jacobian) {
602:     MatGetNullSpace(snes->jacobian,&nullsp);
603:     if (nullsp) {
604:       MatSetNullSpace(J,nullsp);
605:     }
606:   }

608:   PetscInfo1(snes,"Setting default matrix-free operator routines (version %D)\n", version);
609:   if (hasOperator) {

611:     /* This version replaces the user provided Jacobian matrix with a
612:        matrix-free version but still employs the user-provided preconditioner matrix. */
613:     SNESSetJacobian(snes,J,NULL,NULL,NULL);
614:   } else {
615:     /* This version replaces both the user-provided Jacobian and the user-
616:      provided preconditioner Jacobian with the default matrix free version. */
617:     if ((snes->npcside== PC_LEFT) && snes->npc) {
618:       if (!snes->jacobian){SNESSetJacobian(snes,J,NULL,NULL,NULL);}
619:     } else {
620:       KSP       ksp;
621:       PC        pc;
622:       PetscBool match;

624:       SNESSetJacobian(snes,J,J,MatMFFDComputeJacobian,NULL);
625:       /* Force no preconditioner */
626:       SNESGetKSP(snes,&ksp);
627:       KSPGetPC(ksp,&pc);
628:       PetscObjectTypeCompare((PetscObject)pc,PCSHELL,&match);
629:       if (!match) {
630:         PetscInfo(snes,"Setting default matrix-free preconditioner routines\nThat is no preconditioner is being used\n");
631:         PCSetType(pc,PCNONE);
632:       }
633:     }
634:   }
635:   MatDestroy(&J);
636:   return(0);
637: }

639: static PetscErrorCode DMRestrictHook_SNESVecSol(DM dmfine,Mat Restrict,Vec Rscale,Mat Inject,DM dmcoarse,void *ctx)
640: {
641:   SNES           snes = (SNES)ctx;
643:   Vec            Xfine,Xfine_named = NULL,Xcoarse;

646:   if (PetscLogPrintInfo) {
647:     PetscInt finelevel,coarselevel,fineclevel,coarseclevel;
648:     DMGetRefineLevel(dmfine,&finelevel);
649:     DMGetCoarsenLevel(dmfine,&fineclevel);
650:     DMGetRefineLevel(dmcoarse,&coarselevel);
651:     DMGetCoarsenLevel(dmcoarse,&coarseclevel);
652:     PetscInfo4(dmfine,"Restricting SNES solution vector from level %D-%D to level %D-%D\n",finelevel,fineclevel,coarselevel,coarseclevel);
653:   }
654:   if (dmfine == snes->dm) Xfine = snes->vec_sol;
655:   else {
656:     DMGetNamedGlobalVector(dmfine,"SNESVecSol",&Xfine_named);
657:     Xfine = Xfine_named;
658:   }
659:   DMGetNamedGlobalVector(dmcoarse,"SNESVecSol",&Xcoarse);
660:   if (Inject) {
661:     MatRestrict(Inject,Xfine,Xcoarse);
662:   } else {
663:     MatRestrict(Restrict,Xfine,Xcoarse);
664:     VecPointwiseMult(Xcoarse,Xcoarse,Rscale);
665:   }
666:   DMRestoreNamedGlobalVector(dmcoarse,"SNESVecSol",&Xcoarse);
667:   if (Xfine_named) {DMRestoreNamedGlobalVector(dmfine,"SNESVecSol",&Xfine_named);}
668:   return(0);
669: }

671: static PetscErrorCode DMCoarsenHook_SNESVecSol(DM dm,DM dmc,void *ctx)
672: {

676:   DMCoarsenHookAdd(dmc,DMCoarsenHook_SNESVecSol,DMRestrictHook_SNESVecSol,ctx);
677:   return(0);
678: }

680: /* This may be called to rediscretize the operator on levels of linear multigrid. The DM shuffle is so the user can
681:  * safely call SNESGetDM() in their residual evaluation routine. */
682: static PetscErrorCode KSPComputeOperators_SNES(KSP ksp,Mat A,Mat B,void *ctx)
683: {
684:   SNES           snes = (SNES)ctx;
686:   Vec            X,Xnamed = NULL;
687:   DM             dmsave;
688:   void           *ctxsave;
689:   PetscErrorCode (*jac)(SNES,Vec,Mat,Mat,void*) = NULL;

692:   dmsave = snes->dm;
693:   KSPGetDM(ksp,&snes->dm);
694:   if (dmsave == snes->dm) X = snes->vec_sol; /* We are on the finest level */
695:   else {                                     /* We are on a coarser level, this vec was initialized using a DM restrict hook */
696:     DMGetNamedGlobalVector(snes->dm,"SNESVecSol",&Xnamed);
697:     X    = Xnamed;
698:     SNESGetJacobian(snes,NULL,NULL,&jac,&ctxsave);
699:     /* If the DM's don't match up, the MatFDColoring context needed for the jacobian won't match up either -- fixit. */
700:     if (jac == SNESComputeJacobianDefaultColor) {
701:       SNESSetJacobian(snes,NULL,NULL,SNESComputeJacobianDefaultColor,NULL);
702:     }
703:   }
704:   /* Make sure KSP DM has the Jacobian computation routine */
705:   {
706:     DMSNES sdm;

708:     DMGetDMSNES(snes->dm, &sdm);
709:     if (!sdm->ops->computejacobian) {
710:       DMCopyDMSNES(dmsave, snes->dm);
711:     }
712:   }
713:   /* Compute the operators */
714:   SNESComputeJacobian(snes,X,A,B);
715:   /* Put the previous context back */
716:   if (snes->dm != dmsave && jac == SNESComputeJacobianDefaultColor) {
717:     SNESSetJacobian(snes,NULL,NULL,jac,ctxsave);
718:   }

720:   if (Xnamed) {DMRestoreNamedGlobalVector(snes->dm,"SNESVecSol",&Xnamed);}
721:   snes->dm = dmsave;
722:   return(0);
723: }

725: /*@
726:    SNESSetUpMatrices - ensures that matrices are available for SNES, to be called by SNESSetUp_XXX()

728:    Collective

730:    Input Arguments:
731: .  snes - snes to configure

733:    Level: developer

735: .seealso: SNESSetUp()
736: @*/
737: PetscErrorCode SNESSetUpMatrices(SNES snes)
738: {
740:   DM             dm;
741:   DMSNES         sdm;

744:   SNESGetDM(snes,&dm);
745:   DMGetDMSNES(dm,&sdm);
746:   if (!sdm->ops->computejacobian) SETERRQ(PetscObjectComm((PetscObject)snes),PETSC_ERR_PLIB,"DMSNES not properly configured");
747:   else if (!snes->jacobian && snes->mf) {
748:     Mat  J;
749:     void *functx;
750:     MatCreateSNESMF(snes,&J);
751:     MatMFFDSetOptionsPrefix(J,((PetscObject)snes)->prefix);
752:     MatSetFromOptions(J);
753:     SNESGetFunction(snes,NULL,NULL,&functx);
754:     SNESSetJacobian(snes,J,J,NULL,NULL);
755:     MatDestroy(&J);
756:   } else if (snes->mf_operator && !snes->jacobian_pre && !snes->jacobian) {
757:     Mat J,B;
758:     MatCreateSNESMF(snes,&J);
759:     MatMFFDSetOptionsPrefix(J,((PetscObject)snes)->prefix);
760:     MatSetFromOptions(J);
761:     DMCreateMatrix(snes->dm,&B);
762:     /* sdm->computejacobian was already set to reach here */
763:     SNESSetJacobian(snes,J,B,NULL,NULL);
764:     MatDestroy(&J);
765:     MatDestroy(&B);
766:   } else if (!snes->jacobian_pre) {
767:     PetscErrorCode (*nspconstr)(DM, PetscInt, MatNullSpace *);
768:     PetscDS          prob;
769:     Mat              J, B;
770:     MatNullSpace     nullspace = NULL;
771:     PetscBool        hasPrec   = PETSC_FALSE;
772:     PetscInt         Nf;

774:     J    = snes->jacobian;
775:     DMGetDS(dm, &prob);
776:     if (prob) {PetscDSHasJacobianPreconditioner(prob, &hasPrec);}
777:     if (J)            {PetscObjectReference((PetscObject) J);}
778:     else if (hasPrec) {DMCreateMatrix(snes->dm, &J);}
779:     DMCreateMatrix(snes->dm, &B);
780:     PetscDSGetNumFields(prob, &Nf);
781:     DMGetNullSpaceConstructor(snes->dm, Nf, &nspconstr);
782:     if (nspconstr) (*nspconstr)(snes->dm, -1, &nullspace);
783:     MatSetNullSpace(B, nullspace);
784:     MatNullSpaceDestroy(&nullspace);
785:     SNESSetJacobian(snes, J ? J : B, B, NULL, NULL);
786:     MatDestroy(&J);
787:     MatDestroy(&B);
788:   }
789:   {
790:     KSP ksp;
791:     SNESGetKSP(snes,&ksp);
792:     KSPSetComputeOperators(ksp,KSPComputeOperators_SNES,snes);
793:     DMCoarsenHookAdd(snes->dm,DMCoarsenHook_SNESVecSol,DMRestrictHook_SNESVecSol,snes);
794:   }
795:   return(0);
796: }

798: /*@C
799:    SNESMonitorSetFromOptions - Sets a monitor function and viewer appropriate for the type indicated by the user

801:    Collective on SNES

803:    Input Parameters:
804: +  snes - SNES object you wish to monitor
805: .  name - the monitor type one is seeking
806: .  help - message indicating what monitoring is done
807: .  manual - manual page for the monitor
808: .  monitor - the monitor function
809: -  monitorsetup - a function that is called once ONLY if the user selected this monitor that may set additional features of the SNES or PetscViewer objects

811:    Level: developer

813: .seealso: PetscOptionsGetViewer(), PetscOptionsGetReal(), PetscOptionsHasName(), PetscOptionsGetString(),
814:           PetscOptionsGetIntArray(), PetscOptionsGetRealArray(), PetscOptionsBool()
815:           PetscOptionsInt(), PetscOptionsString(), PetscOptionsReal(), PetscOptionsBool(),
816:           PetscOptionsName(), PetscOptionsBegin(), PetscOptionsEnd(), PetscOptionsHead(),
817:           PetscOptionsStringArray(),PetscOptionsRealArray(), PetscOptionsScalar(),
818:           PetscOptionsBoolGroupBegin(), PetscOptionsBoolGroup(), PetscOptionsBoolGroupEnd(),
819:           PetscOptionsFList(), PetscOptionsEList()
820: @*/
821: PetscErrorCode  SNESMonitorSetFromOptions(SNES snes,const char name[],const char help[], const char manual[],PetscErrorCode (*monitor)(SNES,PetscInt,PetscReal,PetscViewerAndFormat*),PetscErrorCode (*monitorsetup)(SNES,PetscViewerAndFormat*))
822: {
823:   PetscErrorCode    ierr;
824:   PetscViewer       viewer;
825:   PetscViewerFormat format;
826:   PetscBool         flg;

829:   PetscOptionsGetViewer(PetscObjectComm((PetscObject)snes),((PetscObject) snes)->options,((PetscObject)snes)->prefix,name,&viewer,&format,&flg);
830:   if (flg) {
831:     PetscViewerAndFormat *vf;
832:     PetscViewerAndFormatCreate(viewer,format,&vf);
833:     PetscObjectDereference((PetscObject)viewer);
834:     if (monitorsetup) {
835:       (*monitorsetup)(snes,vf);
836:     }
837:     SNESMonitorSet(snes,(PetscErrorCode (*)(SNES,PetscInt,PetscReal,void*))monitor,vf,(PetscErrorCode (*)(void**))PetscViewerAndFormatDestroy);
838:   }
839:   return(0);
840: }

842: /*@
843:    SNESSetFromOptions - Sets various SNES and KSP parameters from user options.

845:    Collective on SNES

847:    Input Parameter:
848: .  snes - the SNES context

850:    Options Database Keys:
851: +  -snes_type <type> - newtonls, newtontr, ngmres, ncg, nrichardson, qn, vi, fas, SNESType for complete list
852: .  -snes_stol - convergence tolerance in terms of the norm
853:                 of the change in the solution between steps
854: .  -snes_atol <abstol> - absolute tolerance of residual norm
855: .  -snes_rtol <rtol> - relative decrease in tolerance norm from initial
856: .  -snes_divergence_tolerance <divtol> - if the residual goes above divtol*rnorm0, exit with divergence
857: .  -snes_force_iteration <force> - force SNESSolve() to take at least one iteration
858: .  -snes_max_it <max_it> - maximum number of iterations
859: .  -snes_max_funcs <max_funcs> - maximum number of function evaluations
860: .  -snes_max_fail <max_fail> - maximum number of line search failures allowed before stopping, default is none
861: .  -snes_max_linear_solve_fail - number of linear solver failures before SNESSolve() stops
862: .  -snes_lag_preconditioner <lag> - how often preconditioner is rebuilt (use -1 to never rebuild)
863: .  -snes_lag_jacobian <lag> - how often Jacobian is rebuilt (use -1 to never rebuild)
864: .  -snes_trtol <trtol> - trust region tolerance
865: .  -snes_no_convergence_test - skip convergence test in nonlinear
866:                                solver; hence iterations will continue until max_it
867:                                or some other criterion is reached. Saves expense
868:                                of convergence test
869: .  -snes_monitor [ascii][:filename][:viewer format] - prints residual norm at each iteration. if no filename given prints to stdout
870: .  -snes_monitor_solution [ascii binary draw][:filename][:viewer format] - plots solution at each iteration
871: .  -snes_monitor_residual [ascii binary draw][:filename][:viewer format] - plots residual (not its norm) at each iteration
872: .  -snes_monitor_solution_update [ascii binary draw][:filename][:viewer format] - plots update to solution at each iteration
873: .  -snes_monitor_lg_residualnorm - plots residual norm at each iteration
874: .  -snes_monitor_lg_range - plots residual norm at each iteration
875: .  -snes_fd - use finite differences to compute Jacobian; very slow, only for testing
876: .  -snes_fd_color - use finite differences with coloring to compute Jacobian
877: .  -snes_mf_ksp_monitor - if using matrix-free multiply then print h at each KSP iteration
878: .  -snes_converged_reason - print the reason for convergence/divergence after each solve
879: -  -npc_snes_type <type> - the SNES type to use as a nonlinear preconditioner

881:     Options Database for Eisenstat-Walker method:
882: +  -snes_ksp_ew - use Eisenstat-Walker method for determining linear system convergence
883: .  -snes_ksp_ew_version ver - version of  Eisenstat-Walker method
884: .  -snes_ksp_ew_rtol0 <rtol0> - Sets rtol0
885: .  -snes_ksp_ew_rtolmax <rtolmax> - Sets rtolmax
886: .  -snes_ksp_ew_gamma <gamma> - Sets gamma
887: .  -snes_ksp_ew_alpha <alpha> - Sets alpha
888: .  -snes_ksp_ew_alpha2 <alpha2> - Sets alpha2
889: -  -snes_ksp_ew_threshold <threshold> - Sets threshold

891:    Notes:
892:    To see all options, run your program with the -help option or consult the users manual

894:    Notes:
895:       SNES supports three approaches for computing (approximate) Jacobians: user provided via SNESSetJacobian(), matrix free, and computing explictly with
896:       finite differences and coloring using MatFDColoring. It is also possible to use automatic differentiation and the MatFDColoring object.

898:    Level: beginner

900: .seealso: SNESSetOptionsPrefix(), SNESResetFromOptions(), SNES, SNESCreate()
901: @*/
902: PetscErrorCode  SNESSetFromOptions(SNES snes)
903: {
904:   PetscBool      flg,pcset,persist,set;
905:   PetscInt       i,indx,lag,grids;
906:   const char     *deft        = SNESNEWTONLS;
907:   const char     *convtests[] = {"default","skip"};
908:   SNESKSPEW      *kctx        = NULL;
909:   char           type[256], monfilename[PETSC_MAX_PATH_LEN];
911:   PCSide         pcside;
912:   const char     *optionsprefix;

916:   SNESRegisterAll();
917:   PetscObjectOptionsBegin((PetscObject)snes);
918:   if (((PetscObject)snes)->type_name) deft = ((PetscObject)snes)->type_name;
919:   PetscOptionsFList("-snes_type","Nonlinear solver method","SNESSetType",SNESList,deft,type,256,&flg);
920:   if (flg) {
921:     SNESSetType(snes,type);
922:   } else if (!((PetscObject)snes)->type_name) {
923:     SNESSetType(snes,deft);
924:   }
925:   PetscOptionsReal("-snes_stol","Stop if step length less than","SNESSetTolerances",snes->stol,&snes->stol,NULL);
926:   PetscOptionsReal("-snes_atol","Stop if function norm less than","SNESSetTolerances",snes->abstol,&snes->abstol,NULL);

928:   PetscOptionsReal("-snes_rtol","Stop if decrease in function norm less than","SNESSetTolerances",snes->rtol,&snes->rtol,NULL);
929:   PetscOptionsReal("-snes_divergence_tolerance","Stop if residual norm increases by this factor","SNESSetDivergenceTolerance",snes->divtol,&snes->divtol,NULL);
930:   PetscOptionsInt("-snes_max_it","Maximum iterations","SNESSetTolerances",snes->max_its,&snes->max_its,NULL);
931:   PetscOptionsInt("-snes_max_funcs","Maximum function evaluations","SNESSetTolerances",snes->max_funcs,&snes->max_funcs,NULL);
932:   PetscOptionsInt("-snes_max_fail","Maximum nonlinear step failures","SNESSetMaxNonlinearStepFailures",snes->maxFailures,&snes->maxFailures,NULL);
933:   PetscOptionsInt("-snes_max_linear_solve_fail","Maximum failures in linear solves allowed","SNESSetMaxLinearSolveFailures",snes->maxLinearSolveFailures,&snes->maxLinearSolveFailures,NULL);
934:   PetscOptionsBool("-snes_error_if_not_converged","Generate error if solver does not converge","SNESSetErrorIfNotConverged",snes->errorifnotconverged,&snes->errorifnotconverged,NULL);
935:   PetscOptionsBool("-snes_force_iteration","Force SNESSolve() to take at least one iteration","SNESSetForceIteration",snes->forceiteration,&snes->forceiteration,NULL);
936:   PetscOptionsBool("-snes_check_jacobian_domain_error","Check Jacobian domain error after Jacobian evaluation","SNESCheckJacobianDomainError",snes->checkjacdomainerror,&snes->checkjacdomainerror,NULL);

938:   PetscOptionsInt("-snes_lag_preconditioner","How often to rebuild preconditioner","SNESSetLagPreconditioner",snes->lagpreconditioner,&lag,&flg);
939:   if (flg) {
940:     SNESSetLagPreconditioner(snes,lag);
941:   }
942:   PetscOptionsBool("-snes_lag_preconditioner_persists","Preconditioner lagging through multiple SNES solves","SNESSetLagPreconditionerPersists",snes->lagjac_persist,&persist,&flg);
943:   if (flg) {
944:     SNESSetLagPreconditionerPersists(snes,persist);
945:   }
946:   PetscOptionsInt("-snes_lag_jacobian","How often to rebuild Jacobian","SNESSetLagJacobian",snes->lagjacobian,&lag,&flg);
947:   if (flg) {
948:     SNESSetLagJacobian(snes,lag);
949:   }
950:   PetscOptionsBool("-snes_lag_jacobian_persists","Jacobian lagging through multiple SNES solves","SNESSetLagJacobianPersists",snes->lagjac_persist,&persist,&flg);
951:   if (flg) {
952:     SNESSetLagJacobianPersists(snes,persist);
953:   }

955:   PetscOptionsInt("-snes_grid_sequence","Use grid sequencing to generate initial guess","SNESSetGridSequence",snes->gridsequence,&grids,&flg);
956:   if (flg) {
957:     SNESSetGridSequence(snes,grids);
958:   }

960:   PetscOptionsEList("-snes_convergence_test","Convergence test","SNESSetConvergenceTest",convtests,2,"default",&indx,&flg);
961:   if (flg) {
962:     switch (indx) {
963:     case 0: SNESSetConvergenceTest(snes,SNESConvergedDefault,NULL,NULL); break;
964:     case 1: SNESSetConvergenceTest(snes,SNESConvergedSkip,NULL,NULL);    break;
965:     }
966:   }

968:   PetscOptionsEList("-snes_norm_schedule","SNES Norm schedule","SNESSetNormSchedule",SNESNormSchedules,5,"function",&indx,&flg);
969:   if (flg) { SNESSetNormSchedule(snes,(SNESNormSchedule)indx); }

971:   PetscOptionsEList("-snes_function_type","SNES Norm schedule","SNESSetFunctionType",SNESFunctionTypes,2,"unpreconditioned",&indx,&flg);
972:   if (flg) { SNESSetFunctionType(snes,(SNESFunctionType)indx); }

974:   kctx = (SNESKSPEW*)snes->kspconvctx;

976:   PetscOptionsBool("-snes_ksp_ew","Use Eisentat-Walker linear system convergence test","SNESKSPSetUseEW",snes->ksp_ewconv,&snes->ksp_ewconv,NULL);

978:   PetscOptionsInt("-snes_ksp_ew_version","Version 1, 2 or 3","SNESKSPSetParametersEW",kctx->version,&kctx->version,NULL);
979:   PetscOptionsReal("-snes_ksp_ew_rtol0","0 <= rtol0 < 1","SNESKSPSetParametersEW",kctx->rtol_0,&kctx->rtol_0,NULL);
980:   PetscOptionsReal("-snes_ksp_ew_rtolmax","0 <= rtolmax < 1","SNESKSPSetParametersEW",kctx->rtol_max,&kctx->rtol_max,NULL);
981:   PetscOptionsReal("-snes_ksp_ew_gamma","0 <= gamma <= 1","SNESKSPSetParametersEW",kctx->gamma,&kctx->gamma,NULL);
982:   PetscOptionsReal("-snes_ksp_ew_alpha","1 < alpha <= 2","SNESKSPSetParametersEW",kctx->alpha,&kctx->alpha,NULL);
983:   PetscOptionsReal("-snes_ksp_ew_alpha2","alpha2","SNESKSPSetParametersEW",kctx->alpha2,&kctx->alpha2,NULL);
984:   PetscOptionsReal("-snes_ksp_ew_threshold","0 < threshold < 1","SNESKSPSetParametersEW",kctx->threshold,&kctx->threshold,NULL);

986:   flg  = PETSC_FALSE;
987:   PetscOptionsBool("-snes_monitor_cancel","Remove all monitors","SNESMonitorCancel",flg,&flg,&set);
988:   if (set && flg) {SNESMonitorCancel(snes);}

990:   SNESMonitorSetFromOptions(snes,"-snes_monitor","Monitor norm of function","SNESMonitorDefault",SNESMonitorDefault,NULL);
991:   SNESMonitorSetFromOptions(snes,"-snes_monitor_short","Monitor norm of function with fewer digits","SNESMonitorDefaultShort",SNESMonitorDefaultShort,NULL);
992:   SNESMonitorSetFromOptions(snes,"-snes_monitor_range","Monitor range of elements of function","SNESMonitorRange",SNESMonitorRange,NULL);

994:   SNESMonitorSetFromOptions(snes,"-snes_monitor_ratio","Monitor ratios of the norm of function for consecutive steps","SNESMonitorRatio",SNESMonitorRatio,SNESMonitorRatioSetUp);
995:   SNESMonitorSetFromOptions(snes,"-snes_monitor_field","Monitor norm of function (split into fields)","SNESMonitorDefaultField",SNESMonitorDefaultField,NULL);
996:   SNESMonitorSetFromOptions(snes,"-snes_monitor_solution","View solution at each iteration","SNESMonitorSolution",SNESMonitorSolution,NULL);
997:   SNESMonitorSetFromOptions(snes,"-snes_monitor_solution_update","View correction at each iteration","SNESMonitorSolutionUpdate",SNESMonitorSolutionUpdate,NULL);
998:   SNESMonitorSetFromOptions(snes,"-snes_monitor_residual","View residual at each iteration","SNESMonitorResidual",SNESMonitorResidual,NULL);
999:   SNESMonitorSetFromOptions(snes,"-snes_monitor_jacupdate_spectrum","Print the change in the spectrum of the Jacobian","SNESMonitorJacUpdateSpectrum",SNESMonitorJacUpdateSpectrum,NULL);
1000:   SNESMonitorSetFromOptions(snes,"-snes_monitor_fields","Monitor norm of function per field","SNESMonitorSet",SNESMonitorFields,NULL);

1002:   PetscOptionsString("-snes_monitor_python","Use Python function","SNESMonitorSet",NULL,monfilename,sizeof(monfilename),&flg);
1003:   if (flg) {PetscPythonMonitorSet((PetscObject)snes,monfilename);}

1005:   flg  = PETSC_FALSE;
1006:   PetscOptionsBool("-snes_monitor_lg_residualnorm","Plot function norm at each iteration","SNESMonitorLGResidualNorm",flg,&flg,NULL);
1007:   if (flg) {
1008:     PetscDrawLG ctx;

1010:     SNESMonitorLGCreate(PetscObjectComm((PetscObject)snes),NULL,NULL,PETSC_DECIDE,PETSC_DECIDE,400,300,&ctx);
1011:     SNESMonitorSet(snes,SNESMonitorLGResidualNorm,ctx,(PetscErrorCode (*)(void**))PetscDrawLGDestroy);
1012:   }
1013:   flg  = PETSC_FALSE;
1014:   PetscOptionsBool("-snes_monitor_lg_range","Plot function range at each iteration","SNESMonitorLGRange",flg,&flg,NULL);
1015:   if (flg) {
1016:     PetscViewer ctx;

1018:     PetscViewerDrawOpen(PetscObjectComm((PetscObject)snes),NULL,NULL,PETSC_DECIDE,PETSC_DECIDE,400,300,&ctx);
1019:     SNESMonitorSet(snes,SNESMonitorLGRange,ctx,(PetscErrorCode (*)(void**))PetscViewerDestroy);
1020:   }

1022:   flg  = PETSC_FALSE;
1023:   PetscOptionsBool("-snes_fd","Use finite differences (slow) to compute Jacobian","SNESComputeJacobianDefault",flg,&flg,NULL);
1024:   if (flg) {
1025:     void    *functx;
1026:     DM      dm;
1027:     DMSNES  sdm;
1028:     SNESGetDM(snes,&dm);
1029:     DMGetDMSNES(dm,&sdm);
1030:     sdm->jacobianctx = NULL;
1031:     SNESGetFunction(snes,NULL,NULL,&functx);
1032:     SNESSetJacobian(snes,snes->jacobian,snes->jacobian_pre,SNESComputeJacobianDefault,functx);
1033:     PetscInfo(snes,"Setting default finite difference Jacobian matrix\n");
1034:   }

1036:   flg  = PETSC_FALSE;
1037:   PetscOptionsBool("-snes_fd_function","Use finite differences (slow) to compute function from user objective","SNESObjectiveComputeFunctionDefaultFD",flg,&flg,NULL);
1038:   if (flg) {
1039:     SNESSetFunction(snes,NULL,SNESObjectiveComputeFunctionDefaultFD,NULL);
1040:   }

1042:   flg  = PETSC_FALSE;
1043:   PetscOptionsBool("-snes_fd_color","Use finite differences with coloring to compute Jacobian","SNESComputeJacobianDefaultColor",flg,&flg,NULL);
1044:   if (flg) {
1045:     DM             dm;
1046:     DMSNES         sdm;
1047:     SNESGetDM(snes,&dm);
1048:     DMGetDMSNES(dm,&sdm);
1049:     sdm->jacobianctx = NULL;
1050:     SNESSetJacobian(snes,snes->jacobian,snes->jacobian_pre,SNESComputeJacobianDefaultColor,NULL);
1051:     PetscInfo(snes,"Setting default finite difference coloring Jacobian matrix\n");
1052:   }

1054:   flg  = PETSC_FALSE;
1055:   PetscOptionsBool("-snes_mf_operator","Use a Matrix-Free Jacobian with user-provided preconditioner matrix","SNESSetUseMatrixFree",PETSC_FALSE,&snes->mf_operator,&flg);
1056:   if (flg && snes->mf_operator) {
1057:     snes->mf_operator = PETSC_TRUE;
1058:     snes->mf          = PETSC_TRUE;
1059:   }
1060:   flg  = PETSC_FALSE;
1061:   PetscOptionsBool("-snes_mf","Use a Matrix-Free Jacobian with no preconditioner matrix","SNESSetUseMatrixFree",PETSC_FALSE,&snes->mf,&flg);
1062:   if (!flg && snes->mf_operator) snes->mf = PETSC_TRUE;
1063:   PetscOptionsInt("-snes_mf_version","Matrix-Free routines version 1 or 2","None",snes->mf_version,&snes->mf_version,NULL);

1065:   flg  = PETSC_FALSE;
1066:   SNESGetNPCSide(snes,&pcside);
1067:   PetscOptionsEnum("-snes_npc_side","SNES nonlinear preconditioner side","SNESSetNPCSide",PCSides,(PetscEnum)pcside,(PetscEnum*)&pcside,&flg);
1068:   if (flg) {SNESSetNPCSide(snes,pcside);}

1070: #if defined(PETSC_HAVE_SAWS)
1071:   /*
1072:     Publish convergence information using SAWs
1073:   */
1074:   flg  = PETSC_FALSE;
1075:   PetscOptionsBool("-snes_monitor_saws","Publish SNES progress using SAWs","SNESMonitorSet",flg,&flg,NULL);
1076:   if (flg) {
1077:     void *ctx;
1078:     SNESMonitorSAWsCreate(snes,&ctx);
1079:     SNESMonitorSet(snes,SNESMonitorSAWs,ctx,SNESMonitorSAWsDestroy);
1080:   }
1081: #endif
1082: #if defined(PETSC_HAVE_SAWS)
1083:   {
1084:   PetscBool set;
1085:   flg  = PETSC_FALSE;
1086:   PetscOptionsBool("-snes_saws_block","Block for SAWs at end of SNESSolve","PetscObjectSAWsBlock",((PetscObject)snes)->amspublishblock,&flg,&set);
1087:   if (set) {
1088:     PetscObjectSAWsSetBlock((PetscObject)snes,flg);
1089:   }
1090:   }
1091: #endif

1093:   for (i = 0; i < numberofsetfromoptions; i++) {
1094:     (*othersetfromoptions[i])(snes);
1095:   }

1097:   if (snes->ops->setfromoptions) {
1098:     (*snes->ops->setfromoptions)(PetscOptionsObject,snes);
1099:   }

1101:   /* process any options handlers added with PetscObjectAddOptionsHandler() */
1102:   PetscObjectProcessOptionsHandlers(PetscOptionsObject,(PetscObject)snes);
1103:   PetscOptionsEnd();

1105:   if (snes->linesearch) {
1106:     SNESGetLineSearch(snes, &snes->linesearch);
1107:     SNESLineSearchSetFromOptions(snes->linesearch);
1108:   }

1110:   if (snes->usesksp) {
1111:     if (!snes->ksp) {SNESGetKSP(snes,&snes->ksp);}
1112:     KSPSetOperators(snes->ksp,snes->jacobian,snes->jacobian_pre);
1113:     KSPSetFromOptions(snes->ksp);
1114:   }

1116:   /* if user has set the SNES NPC type via options database, create it. */
1117:   SNESGetOptionsPrefix(snes, &optionsprefix);
1118:   PetscOptionsHasName(((PetscObject)snes)->options,optionsprefix, "-npc_snes_type", &pcset);
1119:   if (pcset && (!snes->npc)) {
1120:     SNESGetNPC(snes, &snes->npc);
1121:   }
1122:   if (snes->npc) {
1123:     SNESSetFromOptions(snes->npc);
1124:   }
1125:   snes->setfromoptionscalled++;
1126:   return(0);
1127: }

1129: /*@
1130:    SNESResetFromOptions - Sets various SNES and KSP parameters from user options ONLY if the SNES was previously set from options

1132:    Collective on SNES

1134:    Input Parameter:
1135: .  snes - the SNES context

1137:    Level: beginner

1139: .seealso: SNESSetFromOptions(), SNESSetOptionsPrefix()
1140: @*/
1141: PetscErrorCode SNESResetFromOptions(SNES snes)
1142: {

1146:   if (snes->setfromoptionscalled) {SNESSetFromOptions(snes);}
1147:   return(0);
1148: }

1150: /*@C
1151:    SNESSetComputeApplicationContext - Sets an optional function to compute a user-defined context for
1152:    the nonlinear solvers.

1154:    Logically Collective on SNES

1156:    Input Parameters:
1157: +  snes - the SNES context
1158: .  compute - function to compute the context
1159: -  destroy - function to destroy the context

1161:    Level: intermediate

1163:    Notes:
1164:    This function is currently not available from Fortran.

1166: .seealso: SNESGetApplicationContext(), SNESSetComputeApplicationContext(), SNESGetApplicationContext()
1167: @*/
1168: PetscErrorCode  SNESSetComputeApplicationContext(SNES snes,PetscErrorCode (*compute)(SNES,void**),PetscErrorCode (*destroy)(void**))
1169: {
1172:   snes->ops->usercompute = compute;
1173:   snes->ops->userdestroy = destroy;
1174:   return(0);
1175: }

1177: /*@
1178:    SNESSetApplicationContext - Sets the optional user-defined context for
1179:    the nonlinear solvers.

1181:    Logically Collective on SNES

1183:    Input Parameters:
1184: +  snes - the SNES context
1185: -  usrP - optional user context

1187:    Level: intermediate

1189:    Fortran Notes:
1190:     To use this from Fortran you must write a Fortran interface definition for this
1191:     function that tells Fortran the Fortran derived data type that you are passing in as the ctx argument.

1193: .seealso: SNESGetApplicationContext()
1194: @*/
1195: PetscErrorCode  SNESSetApplicationContext(SNES snes,void *usrP)
1196: {
1198:   KSP            ksp;

1202:   SNESGetKSP(snes,&ksp);
1203:   KSPSetApplicationContext(ksp,usrP);
1204:   snes->user = usrP;
1205:   return(0);
1206: }

1208: /*@
1209:    SNESGetApplicationContext - Gets the user-defined context for the
1210:    nonlinear solvers.

1212:    Not Collective

1214:    Input Parameter:
1215: .  snes - SNES context

1217:    Output Parameter:
1218: .  usrP - user context

1220:    Fortran Notes:
1221:     To use this from Fortran you must write a Fortran interface definition for this
1222:     function that tells Fortran the Fortran derived data type that you are passing in as the ctx argument.

1224:    Level: intermediate

1226: .seealso: SNESSetApplicationContext()
1227: @*/
1228: PetscErrorCode  SNESGetApplicationContext(SNES snes,void *usrP)
1229: {
1232:   *(void**)usrP = snes->user;
1233:   return(0);
1234: }

1236: /*@
1237:    SNESSetUseMatrixFree - indicates that SNES should use matrix free finite difference matrix vector products internally to apply the Jacobian.

1239:    Collective on SNES

1241:    Input Parameters:
1242: +  snes - SNES context
1243: .  mf_operator - use matrix-free only for the Amat used by SNESSetJacobian(), this means the user provided Pmat will continue to be used
1244: -  mf - use matrix-free for both the Amat and Pmat used by SNESSetJacobian(), both the Amat and Pmat set in SNESSetJacobian() will be ignored

1246:    Options Database:
1247: + -snes_mf - use matrix free for both the mat and pmat operator
1248: . -snes_mf_operator - use matrix free only for the mat operator
1249: . -snes_fd_color - compute the Jacobian via coloring and finite differences.
1250: - -snes_fd - compute the Jacobian via finite differences (slow)

1252:    Level: intermediate

1254:    Notes:
1255:       SNES supports three approaches for computing (approximate) Jacobians: user provided via SNESSetJacobian(), matrix free, and computing explictly with
1256:       finite differences and coloring using MatFDColoring. It is also possible to use automatic differentiation and the MatFDColoring object.

1258: .seealso:   SNESGetUseMatrixFree(), MatCreateSNESMF(), SNESComputeJacobianDefaultColor()
1259: @*/
1260: PetscErrorCode  SNESSetUseMatrixFree(SNES snes,PetscBool mf_operator,PetscBool mf)
1261: {
1266:   snes->mf          = mf_operator ? PETSC_TRUE : mf;
1267:   snes->mf_operator = mf_operator;
1268:   return(0);
1269: }

1271: /*@
1272:    SNESGetUseMatrixFree - indicates if the SNES uses matrix free finite difference matrix vector products to apply the Jacobian.

1274:    Collective on SNES

1276:    Input Parameter:
1277: .  snes - SNES context

1279:    Output Parameters:
1280: +  mf_operator - use matrix-free only for the Amat used by SNESSetJacobian(), this means the user provided Pmat will continue to be used
1281: -  mf - use matrix-free for both the Amat and Pmat used by SNESSetJacobian(), both the Amat and Pmat set in SNESSetJacobian() will be ignored

1283:    Options Database:
1284: + -snes_mf - use matrix free for both the mat and pmat operator
1285: - -snes_mf_operator - use matrix free only for the mat operator

1287:    Level: intermediate

1289: .seealso:   SNESSetUseMatrixFree(), MatCreateSNESMF()
1290: @*/
1291: PetscErrorCode  SNESGetUseMatrixFree(SNES snes,PetscBool *mf_operator,PetscBool *mf)
1292: {
1295:   if (mf)          *mf          = snes->mf;
1296:   if (mf_operator) *mf_operator = snes->mf_operator;
1297:   return(0);
1298: }

1300: /*@
1301:    SNESGetIterationNumber - Gets the number of nonlinear iterations completed
1302:    at this time.

1304:    Not Collective

1306:    Input Parameter:
1307: .  snes - SNES context

1309:    Output Parameter:
1310: .  iter - iteration number

1312:    Notes:
1313:    For example, during the computation of iteration 2 this would return 1.

1315:    This is useful for using lagged Jacobians (where one does not recompute the
1316:    Jacobian at each SNES iteration). For example, the code
1317: .vb
1318:       SNESGetIterationNumber(snes,&it);
1319:       if (!(it % 2)) {
1320:         [compute Jacobian here]
1321:       }
1322: .ve
1323:    can be used in your ComputeJacobian() function to cause the Jacobian to be
1324:    recomputed every second SNES iteration.

1326:    After the SNES solve is complete this will return the number of nonlinear iterations used.

1328:    Level: intermediate

1330: .seealso:   SNESGetLinearSolveIterations()
1331: @*/
1332: PetscErrorCode  SNESGetIterationNumber(SNES snes,PetscInt *iter)
1333: {
1337:   *iter = snes->iter;
1338:   return(0);
1339: }

1341: /*@
1342:    SNESSetIterationNumber - Sets the current iteration number.

1344:    Not Collective

1346:    Input Parameter:
1347: +  snes - SNES context
1348: -  iter - iteration number

1350:    Level: developer

1352: .seealso:   SNESGetLinearSolveIterations()
1353: @*/
1354: PetscErrorCode  SNESSetIterationNumber(SNES snes,PetscInt iter)
1355: {

1360:   PetscObjectSAWsTakeAccess((PetscObject)snes);
1361:   snes->iter = iter;
1362:   PetscObjectSAWsGrantAccess((PetscObject)snes);
1363:   return(0);
1364: }

1366: /*@
1367:    SNESGetNonlinearStepFailures - Gets the number of unsuccessful steps
1368:    attempted by the nonlinear solver.

1370:    Not Collective

1372:    Input Parameter:
1373: .  snes - SNES context

1375:    Output Parameter:
1376: .  nfails - number of unsuccessful steps attempted

1378:    Notes:
1379:    This counter is reset to zero for each successive call to SNESSolve().

1381:    Level: intermediate

1383: .seealso: SNESGetMaxLinearSolveFailures(), SNESGetLinearSolveIterations(), SNESSetMaxLinearSolveFailures(), SNESGetLinearSolveFailures(),
1384:           SNESSetMaxNonlinearStepFailures(), SNESGetMaxNonlinearStepFailures()
1385: @*/
1386: PetscErrorCode  SNESGetNonlinearStepFailures(SNES snes,PetscInt *nfails)
1387: {
1391:   *nfails = snes->numFailures;
1392:   return(0);
1393: }

1395: /*@
1396:    SNESSetMaxNonlinearStepFailures - Sets the maximum number of unsuccessful steps
1397:    attempted by the nonlinear solver before it gives up.

1399:    Not Collective

1401:    Input Parameters:
1402: +  snes     - SNES context
1403: -  maxFails - maximum of unsuccessful steps

1405:    Level: intermediate

1407: .seealso: SNESGetMaxLinearSolveFailures(), SNESGetLinearSolveIterations(), SNESSetMaxLinearSolveFailures(), SNESGetLinearSolveFailures(),
1408:           SNESGetMaxNonlinearStepFailures(), SNESGetNonlinearStepFailures()
1409: @*/
1410: PetscErrorCode  SNESSetMaxNonlinearStepFailures(SNES snes, PetscInt maxFails)
1411: {
1414:   snes->maxFailures = maxFails;
1415:   return(0);
1416: }

1418: /*@
1419:    SNESGetMaxNonlinearStepFailures - Gets the maximum number of unsuccessful steps
1420:    attempted by the nonlinear solver before it gives up.

1422:    Not Collective

1424:    Input Parameter:
1425: .  snes     - SNES context

1427:    Output Parameter:
1428: .  maxFails - maximum of unsuccessful steps

1430:    Level: intermediate

1432: .seealso: SNESGetMaxLinearSolveFailures(), SNESGetLinearSolveIterations(), SNESSetMaxLinearSolveFailures(), SNESGetLinearSolveFailures(),
1433:           SNESSetMaxNonlinearStepFailures(), SNESGetNonlinearStepFailures()

1435: @*/
1436: PetscErrorCode  SNESGetMaxNonlinearStepFailures(SNES snes, PetscInt *maxFails)
1437: {
1441:   *maxFails = snes->maxFailures;
1442:   return(0);
1443: }

1445: /*@
1446:    SNESGetNumberFunctionEvals - Gets the number of user provided function evaluations
1447:      done by SNES.

1449:    Not Collective

1451:    Input Parameter:
1452: .  snes     - SNES context

1454:    Output Parameter:
1455: .  nfuncs - number of evaluations

1457:    Level: intermediate

1459:    Notes:
1460:     Reset every time SNESSolve is called unless SNESSetCountersReset() is used.

1462: .seealso: SNESGetMaxLinearSolveFailures(), SNESGetLinearSolveIterations(), SNESSetMaxLinearSolveFailures(), SNESGetLinearSolveFailures(), SNESSetCountersReset()
1463: @*/
1464: PetscErrorCode  SNESGetNumberFunctionEvals(SNES snes, PetscInt *nfuncs)
1465: {
1469:   *nfuncs = snes->nfuncs;
1470:   return(0);
1471: }

1473: /*@
1474:    SNESGetLinearSolveFailures - Gets the number of failed (non-converged)
1475:    linear solvers.

1477:    Not Collective

1479:    Input Parameter:
1480: .  snes - SNES context

1482:    Output Parameter:
1483: .  nfails - number of failed solves

1485:    Level: intermediate

1487:    Options Database Keys:
1488: . -snes_max_linear_solve_fail <num> - The number of failures before the solve is terminated

1490:    Notes:
1491:    This counter is reset to zero for each successive call to SNESSolve().

1493: .seealso: SNESGetMaxLinearSolveFailures(), SNESGetLinearSolveIterations(), SNESSetMaxLinearSolveFailures()
1494: @*/
1495: PetscErrorCode  SNESGetLinearSolveFailures(SNES snes,PetscInt *nfails)
1496: {
1500:   *nfails = snes->numLinearSolveFailures;
1501:   return(0);
1502: }

1504: /*@
1505:    SNESSetMaxLinearSolveFailures - the number of failed linear solve attempts
1506:    allowed before SNES returns with a diverged reason of SNES_DIVERGED_LINEAR_SOLVE

1508:    Logically Collective on SNES

1510:    Input Parameters:
1511: +  snes     - SNES context
1512: -  maxFails - maximum allowed linear solve failures

1514:    Level: intermediate

1516:    Options Database Keys:
1517: . -snes_max_linear_solve_fail <num> - The number of failures before the solve is terminated

1519:    Notes:
1520:     By default this is 0; that is SNES returns on the first failed linear solve

1522: .seealso: SNESGetLinearSolveFailures(), SNESGetMaxLinearSolveFailures(), SNESGetLinearSolveIterations()
1523: @*/
1524: PetscErrorCode  SNESSetMaxLinearSolveFailures(SNES snes, PetscInt maxFails)
1525: {
1529:   snes->maxLinearSolveFailures = maxFails;
1530:   return(0);
1531: }

1533: /*@
1534:    SNESGetMaxLinearSolveFailures - gets the maximum number of linear solve failures that
1535:      are allowed before SNES terminates

1537:    Not Collective

1539:    Input Parameter:
1540: .  snes     - SNES context

1542:    Output Parameter:
1543: .  maxFails - maximum of unsuccessful solves allowed

1545:    Level: intermediate

1547:    Notes:
1548:     By default this is 1; that is SNES returns on the first failed linear solve

1550: .seealso: SNESGetLinearSolveFailures(), SNESGetLinearSolveIterations(), SNESSetMaxLinearSolveFailures(),
1551: @*/
1552: PetscErrorCode  SNESGetMaxLinearSolveFailures(SNES snes, PetscInt *maxFails)
1553: {
1557:   *maxFails = snes->maxLinearSolveFailures;
1558:   return(0);
1559: }

1561: /*@
1562:    SNESGetLinearSolveIterations - Gets the total number of linear iterations
1563:    used by the nonlinear solver.

1565:    Not Collective

1567:    Input Parameter:
1568: .  snes - SNES context

1570:    Output Parameter:
1571: .  lits - number of linear iterations

1573:    Notes:
1574:    This counter is reset to zero for each successive call to SNESSolve() unless SNESSetCountersReset() is used.

1576:    If the linear solver fails inside the SNESSolve() the iterations for that call to the linear solver are not included. If you wish to count them
1577:    then call KSPGetIterationNumber() after the failed solve.

1579:    Level: intermediate

1581: .seealso:  SNESGetIterationNumber(), SNESGetLinearSolveFailures(), SNESGetMaxLinearSolveFailures(), SNESSetCountersReset()
1582: @*/
1583: PetscErrorCode  SNESGetLinearSolveIterations(SNES snes,PetscInt *lits)
1584: {
1588:   *lits = snes->linear_its;
1589:   return(0);
1590: }

1592: /*@
1593:    SNESSetCountersReset - Sets whether or not the counters for linear iterations and function evaluations
1594:    are reset every time SNESSolve() is called.

1596:    Logically Collective on SNES

1598:    Input Parameter:
1599: +  snes - SNES context
1600: -  reset - whether to reset the counters or not

1602:    Notes:
1603:    This defaults to PETSC_TRUE

1605:    Level: developer

1607: .seealso:  SNESGetNumberFunctionEvals(), SNESGetLinearSolveIterations(), SNESGetNPC()
1608: @*/
1609: PetscErrorCode  SNESSetCountersReset(SNES snes,PetscBool reset)
1610: {
1614:   snes->counters_reset = reset;
1615:   return(0);
1616: }


1619: /*@
1620:    SNESSetKSP - Sets a KSP context for the SNES object to use

1622:    Not Collective, but the SNES and KSP objects must live on the same MPI_Comm

1624:    Input Parameters:
1625: +  snes - the SNES context
1626: -  ksp - the KSP context

1628:    Notes:
1629:    The SNES object already has its KSP object, you can obtain with SNESGetKSP()
1630:    so this routine is rarely needed.

1632:    The KSP object that is already in the SNES object has its reference count
1633:    decreased by one.

1635:    Level: developer

1637: .seealso: KSPGetPC(), SNESCreate(), KSPCreate(), SNESSetKSP()
1638: @*/
1639: PetscErrorCode  SNESSetKSP(SNES snes,KSP ksp)
1640: {

1647:   PetscObjectReference((PetscObject)ksp);
1648:   if (snes->ksp) {PetscObjectDereference((PetscObject)snes->ksp);}
1649:   snes->ksp = ksp;
1650:   return(0);
1651: }

1653: /* -----------------------------------------------------------*/
1654: /*@
1655:    SNESCreate - Creates a nonlinear solver context.

1657:    Collective

1659:    Input Parameters:
1660: .  comm - MPI communicator

1662:    Output Parameter:
1663: .  outsnes - the new SNES context

1665:    Options Database Keys:
1666: +   -snes_mf - Activates default matrix-free Jacobian-vector products,
1667:                and no preconditioning matrix
1668: .   -snes_mf_operator - Activates default matrix-free Jacobian-vector
1669:                products, and a user-provided preconditioning matrix
1670:                as set by SNESSetJacobian()
1671: -   -snes_fd - Uses (slow!) finite differences to compute Jacobian

1673:    Level: beginner

1675:    Developer Notes:
1676:     SNES always creates a KSP object even though many SNES methods do not use it. This is
1677:                     unfortunate and should be fixed at some point. The flag snes->usesksp indicates if the
1678:                     particular method does use KSP and regulates if the information about the KSP is printed
1679:                     in SNESView(). TSSetFromOptions() does call SNESSetFromOptions() which can lead to users being confused
1680:                     by help messages about meaningless SNES options.

1682:                     SNES always creates the snes->kspconvctx even though it is used by only one type. This should
1683:                     be fixed.

1685: .seealso: SNESSolve(), SNESDestroy(), SNES, SNESSetLagPreconditioner()

1687: @*/
1688: PetscErrorCode  SNESCreate(MPI_Comm comm,SNES *outsnes)
1689: {
1691:   SNES           snes;
1692:   SNESKSPEW      *kctx;

1696:   *outsnes = NULL;
1697:   SNESInitializePackage();

1699:   PetscHeaderCreate(snes,SNES_CLASSID,"SNES","Nonlinear solver","SNES",comm,SNESDestroy,SNESView);

1701:   snes->ops->converged    = SNESConvergedDefault;
1702:   snes->usesksp           = PETSC_TRUE;
1703:   snes->tolerancesset     = PETSC_FALSE;
1704:   snes->max_its           = 50;
1705:   snes->max_funcs         = 10000;
1706:   snes->norm              = 0.0;
1707:   snes->xnorm             = 0.0;
1708:   snes->ynorm             = 0.0;
1709:   snes->normschedule      = SNES_NORM_ALWAYS;
1710:   snes->functype          = SNES_FUNCTION_DEFAULT;
1711: #if defined(PETSC_USE_REAL_SINGLE)
1712:   snes->rtol              = 1.e-5;
1713: #else
1714:   snes->rtol              = 1.e-8;
1715: #endif
1716:   snes->ttol              = 0.0;
1717: #if defined(PETSC_USE_REAL_SINGLE)
1718:   snes->abstol            = 1.e-25;
1719: #else
1720:   snes->abstol            = 1.e-50;
1721: #endif
1722: #if defined(PETSC_USE_REAL_SINGLE)
1723:   snes->stol              = 1.e-5;
1724: #else
1725:   snes->stol              = 1.e-8;
1726: #endif
1727: #if defined(PETSC_USE_REAL_SINGLE)
1728:   snes->deltatol          = 1.e-6;
1729: #else
1730:   snes->deltatol          = 1.e-12;
1731: #endif
1732:   snes->divtol            = 1.e4;
1733:   snes->rnorm0            = 0;
1734:   snes->nfuncs            = 0;
1735:   snes->numFailures       = 0;
1736:   snes->maxFailures       = 1;
1737:   snes->linear_its        = 0;
1738:   snes->lagjacobian       = 1;
1739:   snes->jac_iter          = 0;
1740:   snes->lagjac_persist    = PETSC_FALSE;
1741:   snes->lagpreconditioner = 1;
1742:   snes->pre_iter          = 0;
1743:   snes->lagpre_persist    = PETSC_FALSE;
1744:   snes->numbermonitors    = 0;
1745:   snes->data              = NULL;
1746:   snes->setupcalled       = PETSC_FALSE;
1747:   snes->ksp_ewconv        = PETSC_FALSE;
1748:   snes->nwork             = 0;
1749:   snes->work              = NULL;
1750:   snes->nvwork            = 0;
1751:   snes->vwork             = NULL;
1752:   snes->conv_hist_len     = 0;
1753:   snes->conv_hist_max     = 0;
1754:   snes->conv_hist         = NULL;
1755:   snes->conv_hist_its     = NULL;
1756:   snes->conv_hist_reset   = PETSC_TRUE;
1757:   snes->counters_reset    = PETSC_TRUE;
1758:   snes->vec_func_init_set = PETSC_FALSE;
1759:   snes->reason            = SNES_CONVERGED_ITERATING;
1760:   snes->npcside           = PC_RIGHT;
1761:   snes->setfromoptionscalled = 0;

1763:   snes->mf          = PETSC_FALSE;
1764:   snes->mf_operator = PETSC_FALSE;
1765:   snes->mf_version  = 1;

1767:   snes->numLinearSolveFailures = 0;
1768:   snes->maxLinearSolveFailures = 1;

1770:   snes->vizerotolerance = 1.e-8;
1771:   snes->checkjacdomainerror = PetscDefined(USE_DEBUG) ? PETSC_TRUE : PETSC_FALSE;

1773:   /* Set this to true if the implementation of SNESSolve_XXX does compute the residual at the final solution. */
1774:   snes->alwayscomputesfinalresidual = PETSC_FALSE;

1776:   /* Create context to compute Eisenstat-Walker relative tolerance for KSP */
1777:   PetscNewLog(snes,&kctx);

1779:   snes->kspconvctx  = (void*)kctx;
1780:   kctx->version     = 2;
1781:   kctx->rtol_0      = .3; /* Eisenstat and Walker suggest rtol_0=.5, but
1782:                              this was too large for some test cases */
1783:   kctx->rtol_last   = 0.0;
1784:   kctx->rtol_max    = .9;
1785:   kctx->gamma       = 1.0;
1786:   kctx->alpha       = .5*(1.0 + PetscSqrtReal(5.0));
1787:   kctx->alpha2      = kctx->alpha;
1788:   kctx->threshold   = .1;
1789:   kctx->lresid_last = 0.0;
1790:   kctx->norm_last   = 0.0;

1792:   *outsnes = snes;
1793:   return(0);
1794: }

1796: /*MC
1797:     SNESFunction - Functional form used to convey the nonlinear function to be solved by SNES

1799:      Synopsis:
1800:      #include "petscsnes.h"
1801:      PetscErrorCode SNESFunction(SNES snes,Vec x,Vec f,void *ctx);

1803:      Collective on snes

1805:      Input Parameters:
1806: +     snes - the SNES context
1807: .     x    - state at which to evaluate residual
1808: -     ctx     - optional user-defined function context, passed in with SNESSetFunction()

1810:      Output Parameter:
1811: .     f  - vector to put residual (function value)

1813:    Level: intermediate

1815: .seealso:   SNESSetFunction(), SNESGetFunction()
1816: M*/

1818: /*@C
1819:    SNESSetFunction - Sets the function evaluation routine and function
1820:    vector for use by the SNES routines in solving systems of nonlinear
1821:    equations.

1823:    Logically Collective on SNES

1825:    Input Parameters:
1826: +  snes - the SNES context
1827: .  r - vector to store function value
1828: .  f - function evaluation routine; see SNESFunction for calling sequence details
1829: -  ctx - [optional] user-defined context for private data for the
1830:          function evaluation routine (may be NULL)

1832:    Notes:
1833:    The Newton-like methods typically solve linear systems of the form
1834: $      f'(x) x = -f(x),
1835:    where f'(x) denotes the Jacobian matrix and f(x) is the function.

1837:    Level: beginner

1839: .seealso: SNESGetFunction(), SNESComputeFunction(), SNESSetJacobian(), SNESSetPicard(), SNESFunction
1840: @*/
1841: PetscErrorCode  SNESSetFunction(SNES snes,Vec r,PetscErrorCode (*f)(SNES,Vec,Vec,void*),void *ctx)
1842: {
1844:   DM             dm;

1848:   if (r) {
1851:     PetscObjectReference((PetscObject)r);
1852:     VecDestroy(&snes->vec_func);

1854:     snes->vec_func = r;
1855:   }
1856:   SNESGetDM(snes,&dm);
1857:   DMSNESSetFunction(dm,f,ctx);
1858:   return(0);
1859: }


1862: /*@C
1863:    SNESSetInitialFunction - Sets the function vector to be used as the
1864:    function norm at the initialization of the method.  In some
1865:    instances, the user has precomputed the function before calling
1866:    SNESSolve.  This function allows one to avoid a redundant call
1867:    to SNESComputeFunction in that case.

1869:    Logically Collective on SNES

1871:    Input Parameters:
1872: +  snes - the SNES context
1873: -  f - vector to store function value

1875:    Notes:
1876:    This should not be modified during the solution procedure.

1878:    This is used extensively in the SNESFAS hierarchy and in nonlinear preconditioning.

1880:    Level: developer

1882: .seealso: SNESSetFunction(), SNESComputeFunction(), SNESSetInitialFunctionNorm()
1883: @*/
1884: PetscErrorCode  SNESSetInitialFunction(SNES snes, Vec f)
1885: {
1887:   Vec            vec_func;

1893:   if (snes->npcside== PC_LEFT && snes->functype == SNES_FUNCTION_PRECONDITIONED) {
1894:     snes->vec_func_init_set = PETSC_FALSE;
1895:     return(0);
1896:   }
1897:   SNESGetFunction(snes,&vec_func,NULL,NULL);
1898:   VecCopy(f, vec_func);

1900:   snes->vec_func_init_set = PETSC_TRUE;
1901:   return(0);
1902: }

1904: /*@
1905:    SNESSetNormSchedule - Sets the SNESNormSchedule used in covergence and monitoring
1906:    of the SNES method.

1908:    Logically Collective on SNES

1910:    Input Parameters:
1911: +  snes - the SNES context
1912: -  normschedule - the frequency of norm computation

1914:    Options Database Key:
1915: .  -snes_norm_schedule <none, always, initialonly, finalonly, initalfinalonly>

1917:    Notes:
1918:    Only certain SNES methods support certain SNESNormSchedules.  Most require evaluation
1919:    of the nonlinear function and the taking of its norm at every iteration to
1920:    even ensure convergence at all.  However, methods such as custom Gauss-Seidel methods
1921:    (SNESNGS) and the like do not require the norm of the function to be computed, and therfore
1922:    may either be monitored for convergence or not.  As these are often used as nonlinear
1923:    preconditioners, monitoring the norm of their error is not a useful enterprise within
1924:    their solution.

1926:    Level: developer

1928: .seealso: SNESGetNormSchedule(), SNESComputeFunction(), VecNorm(), SNESSetFunction(), SNESSetInitialFunction(), SNESNormSchedule
1929: @*/
1930: PetscErrorCode  SNESSetNormSchedule(SNES snes, SNESNormSchedule normschedule)
1931: {
1934:   snes->normschedule = normschedule;
1935:   return(0);
1936: }


1939: /*@
1940:    SNESGetNormSchedule - Gets the SNESNormSchedule used in covergence and monitoring
1941:    of the SNES method.

1943:    Logically Collective on SNES

1945:    Input Parameters:
1946: +  snes - the SNES context
1947: -  normschedule - the type of the norm used

1949:    Level: advanced

1951: .seealso: SNESSetNormSchedule(), SNESComputeFunction(), VecNorm(), SNESSetFunction(), SNESSetInitialFunction(), SNESNormSchedule
1952: @*/
1953: PetscErrorCode  SNESGetNormSchedule(SNES snes, SNESNormSchedule *normschedule)
1954: {
1957:   *normschedule = snes->normschedule;
1958:   return(0);
1959: }


1962: /*@
1963:   SNESSetFunctionNorm - Sets the last computed residual norm.

1965:   Logically Collective on SNES

1967:   Input Parameters:
1968: + snes - the SNES context

1970: - normschedule - the frequency of norm computation

1972:   Level: developer

1974: .seealso: SNESGetNormSchedule(), SNESComputeFunction(), VecNorm(), SNESSetFunction(), SNESSetInitialFunction(), SNESNormSchedule
1975: @*/
1976: PetscErrorCode SNESSetFunctionNorm(SNES snes, PetscReal norm)
1977: {
1980:   snes->norm = norm;
1981:   return(0);
1982: }

1984: /*@
1985:   SNESGetFunctionNorm - Gets the last computed norm of the residual

1987:   Not Collective

1989:   Input Parameter:
1990: . snes - the SNES context

1992:   Output Parameter:
1993: . norm - the last computed residual norm

1995:   Level: developer

1997: .seealso: SNESSetNormSchedule(), SNESComputeFunction(), VecNorm(), SNESSetFunction(), SNESSetInitialFunction(), SNESNormSchedule
1998: @*/
1999: PetscErrorCode SNESGetFunctionNorm(SNES snes, PetscReal *norm)
2000: {
2004:   *norm = snes->norm;
2005:   return(0);
2006: }

2008: /*@
2009:   SNESGetUpdateNorm - Gets the last computed norm of the Newton update

2011:   Not Collective

2013:   Input Parameter:
2014: . snes - the SNES context

2016:   Output Parameter:
2017: . ynorm - the last computed update norm

2019:   Level: developer

2021: .seealso: SNESSetNormSchedule(), SNESComputeFunction(), SNESGetFunctionNorm()
2022: @*/
2023: PetscErrorCode SNESGetUpdateNorm(SNES snes, PetscReal *ynorm)
2024: {
2028:   *ynorm = snes->ynorm;
2029:   return(0);
2030: }

2032: /*@
2033:   SNESGetSolutionNorm - Gets the last computed norm of the solution

2035:   Not Collective

2037:   Input Parameter:
2038: . snes - the SNES context

2040:   Output Parameter:
2041: . xnorm - the last computed solution norm

2043:   Level: developer

2045: .seealso: SNESSetNormSchedule(), SNESComputeFunction(), SNESGetFunctionNorm(), SNESGetUpdateNorm()
2046: @*/
2047: PetscErrorCode SNESGetSolutionNorm(SNES snes, PetscReal *xnorm)
2048: {
2052:   *xnorm = snes->xnorm;
2053:   return(0);
2054: }

2056: /*@C
2057:    SNESSetFunctionType - Sets the SNESNormSchedule used in covergence and monitoring
2058:    of the SNES method.

2060:    Logically Collective on SNES

2062:    Input Parameters:
2063: +  snes - the SNES context
2064: -  normschedule - the frequency of norm computation

2066:    Notes:
2067:    Only certain SNES methods support certain SNESNormSchedules.  Most require evaluation
2068:    of the nonlinear function and the taking of its norm at every iteration to
2069:    even ensure convergence at all.  However, methods such as custom Gauss-Seidel methods
2070:    (SNESNGS) and the like do not require the norm of the function to be computed, and therfore
2071:    may either be monitored for convergence or not.  As these are often used as nonlinear
2072:    preconditioners, monitoring the norm of their error is not a useful enterprise within
2073:    their solution.

2075:    Level: developer

2077: .seealso: SNESGetNormSchedule(), SNESComputeFunction(), VecNorm(), SNESSetFunction(), SNESSetInitialFunction(), SNESNormSchedule
2078: @*/
2079: PetscErrorCode  SNESSetFunctionType(SNES snes, SNESFunctionType type)
2080: {
2083:   snes->functype = type;
2084:   return(0);
2085: }


2088: /*@C
2089:    SNESGetFunctionType - Gets the SNESNormSchedule used in covergence and monitoring
2090:    of the SNES method.

2092:    Logically Collective on SNES

2094:    Input Parameters:
2095: +  snes - the SNES context
2096: -  normschedule - the type of the norm used

2098:    Level: advanced

2100: .seealso: SNESSetNormSchedule(), SNESComputeFunction(), VecNorm(), SNESSetFunction(), SNESSetInitialFunction(), SNESNormSchedule
2101: @*/
2102: PetscErrorCode  SNESGetFunctionType(SNES snes, SNESFunctionType *type)
2103: {
2106:   *type = snes->functype;
2107:   return(0);
2108: }

2110: /*MC
2111:     SNESNGSFunction - function used to convey a Gauss-Seidel sweep on the nonlinear function

2113:      Synopsis:
2114:  #include <petscsnes.h>
2115: $    SNESNGSFunction(SNES snes,Vec x,Vec b,void *ctx);

2117:      Collective on snes

2119:      Input Parameters:
2120: +  X   - solution vector
2121: .  B   - RHS vector
2122: -  ctx - optional user-defined Gauss-Seidel context

2124:      Output Parameter:
2125: .  X   - solution vector

2127:    Level: intermediate

2129: .seealso:   SNESSetNGS(), SNESGetNGS()
2130: M*/

2132: /*@C
2133:    SNESSetNGS - Sets the user nonlinear Gauss-Seidel routine for
2134:    use with composed nonlinear solvers.

2136:    Input Parameters:
2137: +  snes   - the SNES context
2138: .  f - function evaluation routine to apply Gauss-Seidel see SNESNGSFunction
2139: -  ctx    - [optional] user-defined context for private data for the
2140:             smoother evaluation routine (may be NULL)

2142:    Notes:
2143:    The NGS routines are used by the composed nonlinear solver to generate
2144:     a problem appropriate update to the solution, particularly FAS.

2146:    Level: intermediate

2148: .seealso: SNESGetFunction(), SNESComputeNGS()
2149: @*/
2150: PetscErrorCode SNESSetNGS(SNES snes,PetscErrorCode (*f)(SNES,Vec,Vec,void*),void *ctx)
2151: {
2153:   DM             dm;

2157:   SNESGetDM(snes,&dm);
2158:   DMSNESSetNGS(dm,f,ctx);
2159:   return(0);
2160: }

2162: PetscErrorCode SNESPicardComputeFunction(SNES snes,Vec x,Vec f,void *ctx)
2163: {
2165:   DM             dm;
2166:   DMSNES         sdm;

2169:   SNESGetDM(snes,&dm);
2170:   DMGetDMSNES(dm,&sdm);
2171:   if (!sdm->ops->computepfunction) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_WRONGSTATE, "Must call SNESSetPicard() to provide Picard function.");
2172:   if (!sdm->ops->computepjacobian) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_WRONGSTATE, "Must call SNESSetPicard() to provide Picard Jacobian.");
2173:   /*  A(x)*x - b(x) */
2174:   PetscStackPush("SNES Picard user function");
2175:   (*sdm->ops->computepfunction)(snes,x,f,sdm->pctx);
2176:   PetscStackPop;
2177:   PetscStackPush("SNES Picard user Jacobian");
2178:   (*sdm->ops->computepjacobian)(snes,x,snes->jacobian,snes->jacobian_pre,sdm->pctx);
2179:   PetscStackPop;
2180:   VecScale(f,-1.0);
2181:   MatMultAdd(snes->jacobian,x,f,f);
2182:   return(0);
2183: }

2185: PetscErrorCode SNESPicardComputeJacobian(SNES snes,Vec x1,Mat J,Mat B,void *ctx)
2186: {
2188:   /* the jacobian matrix should be pre-filled in SNESPicardComputeFunction */
2189:   return(0);
2190: }

2192: /*@C
2193:    SNESSetPicard - Use SNES to solve the semilinear-system A(x) x = b(x) via a Picard type iteration (Picard linearization)

2195:    Logically Collective on SNES

2197:    Input Parameters:
2198: +  snes - the SNES context
2199: .  r - vector to store function value
2200: .  b - function evaluation routine
2201: .  Amat - matrix with which A(x) x - b(x) is to be computed
2202: .  Pmat - matrix from which preconditioner is computed (usually the same as Amat)
2203: .  J  - function to compute matrix value, see SNESJacobianFunction for details on its calling sequence
2204: -  ctx - [optional] user-defined context for private data for the
2205:          function evaluation routine (may be NULL)

2207:    Notes:
2208:     We do not recomemend using this routine. It is far better to provide the nonlinear function F() and some approximation to the Jacobian and use
2209:     an approximate Newton solver. This interface is provided to allow porting/testing a previous Picard based code in PETSc before converting it to approximate Newton.

2211:     One can call SNESSetPicard() or SNESSetFunction() (and possibly SNESSetJacobian()) but cannot call both

2213: $     Solves the equation A(x) x = b(x) via the defect correction algorithm A(x^{n}) (x^{n+1} - x^{n}) = b(x^{n}) - A(x^{n})x^{n}
2214: $     Note that when an exact solver is used this corresponds to the "classic" Picard A(x^{n}) x^{n+1} = b(x^{n}) iteration.

2216:      Run with -snes_mf_operator to solve the system with Newton's method using A(x^{n}) to construct the preconditioner.

2218:    We implement the defect correction form of the Picard iteration because it converges much more generally when inexact linear solvers are used then
2219:    the direct Picard iteration A(x^n) x^{n+1} = b(x^n)

2221:    There is some controversity over the definition of a Picard iteration for nonlinear systems but almost everyone agrees that it involves a linear solve and some
2222:    believe it is the iteration  A(x^{n}) x^{n+1} = b(x^{n}) hence we use the name Picard. If anyone has an authoritative  reference that defines the Picard iteration
2223:    different please contact us at petsc-dev@mcs.anl.gov and we'll have an entirely new argument :-).

2225:    Level: intermediate

2227: .seealso: SNESGetFunction(), SNESSetFunction(), SNESComputeFunction(), SNESSetJacobian(), SNESGetPicard(), SNESLineSearchPreCheckPicard(), SNESJacobianFunction
2228: @*/
2229: PetscErrorCode  SNESSetPicard(SNES snes,Vec r,PetscErrorCode (*b)(SNES,Vec,Vec,void*),Mat Amat, Mat Pmat, PetscErrorCode (*J)(SNES,Vec,Mat,Mat,void*),void *ctx)
2230: {
2232:   DM             dm;

2236:   SNESGetDM(snes, &dm);
2237:   DMSNESSetPicard(dm,b,J,ctx);
2238:   SNESSetFunction(snes,r,SNESPicardComputeFunction,ctx);
2239:   SNESSetJacobian(snes,Amat,Pmat,SNESPicardComputeJacobian,ctx);
2240:   return(0);
2241: }

2243: /*@C
2244:    SNESGetPicard - Returns the context for the Picard iteration

2246:    Not Collective, but Vec is parallel if SNES is parallel. Collective if Vec is requested, but has not been created yet.

2248:    Input Parameter:
2249: .  snes - the SNES context

2251:    Output Parameter:
2252: +  r - the function (or NULL)
2253: .  f - the function (or NULL); see SNESFunction for calling sequence details
2254: .  Amat - the matrix used to defined the operation A(x) x - b(x) (or NULL)
2255: .  Pmat  - the matrix from which the preconditioner will be constructed (or NULL)
2256: .  J - the function for matrix evaluation (or NULL); see SNESJacobianFunction for calling sequence details
2257: -  ctx - the function context (or NULL)

2259:    Level: advanced

2261: .seealso: SNESSetPicard(), SNESGetFunction(), SNESGetJacobian(), SNESGetDM(), SNESFunction, SNESJacobianFunction
2262: @*/
2263: PetscErrorCode  SNESGetPicard(SNES snes,Vec *r,PetscErrorCode (**f)(SNES,Vec,Vec,void*),Mat *Amat, Mat *Pmat, PetscErrorCode (**J)(SNES,Vec,Mat,Mat,void*),void **ctx)
2264: {
2266:   DM             dm;

2270:   SNESGetFunction(snes,r,NULL,NULL);
2271:   SNESGetJacobian(snes,Amat,Pmat,NULL,NULL);
2272:   SNESGetDM(snes,&dm);
2273:   DMSNESGetPicard(dm,f,J,ctx);
2274:   return(0);
2275: }

2277: /*@C
2278:    SNESSetComputeInitialGuess - Sets a routine used to compute an initial guess for the problem

2280:    Logically Collective on SNES

2282:    Input Parameters:
2283: +  snes - the SNES context
2284: .  func - function evaluation routine
2285: -  ctx - [optional] user-defined context for private data for the
2286:          function evaluation routine (may be NULL)

2288:    Calling sequence of func:
2289: $    func (SNES snes,Vec x,void *ctx);

2291: .  f - function vector
2292: -  ctx - optional user-defined function context

2294:    Level: intermediate

2296: .seealso: SNESGetFunction(), SNESComputeFunction(), SNESSetJacobian()
2297: @*/
2298: PetscErrorCode  SNESSetComputeInitialGuess(SNES snes,PetscErrorCode (*func)(SNES,Vec,void*),void *ctx)
2299: {
2302:   if (func) snes->ops->computeinitialguess = func;
2303:   if (ctx)  snes->initialguessP            = ctx;
2304:   return(0);
2305: }

2307: /* --------------------------------------------------------------- */
2308: /*@C
2309:    SNESGetRhs - Gets the vector for solving F(x) = rhs. If rhs is not set
2310:    it assumes a zero right hand side.

2312:    Logically Collective on SNES

2314:    Input Parameter:
2315: .  snes - the SNES context

2317:    Output Parameter:
2318: .  rhs - the right hand side vector or NULL if the right hand side vector is null

2320:    Level: intermediate

2322: .seealso: SNESGetSolution(), SNESGetFunction(), SNESComputeFunction(), SNESSetJacobian(), SNESSetFunction()
2323: @*/
2324: PetscErrorCode  SNESGetRhs(SNES snes,Vec *rhs)
2325: {
2329:   *rhs = snes->vec_rhs;
2330:   return(0);
2331: }

2333: /*@
2334:    SNESComputeFunction - Calls the function that has been set with SNESSetFunction().

2336:    Collective on SNES

2338:    Input Parameters:
2339: +  snes - the SNES context
2340: -  x - input vector

2342:    Output Parameter:
2343: .  y - function vector, as set by SNESSetFunction()

2345:    Notes:
2346:    SNESComputeFunction() is typically used within nonlinear solvers
2347:    implementations, so most users would not generally call this routine
2348:    themselves.

2350:    Level: developer

2352: .seealso: SNESSetFunction(), SNESGetFunction()
2353: @*/
2354: PetscErrorCode  SNESComputeFunction(SNES snes,Vec x,Vec y)
2355: {
2357:   DM             dm;
2358:   DMSNES         sdm;

2366:   VecValidValues(x,2,PETSC_TRUE);

2368:   SNESGetDM(snes,&dm);
2369:   DMGetDMSNES(dm,&sdm);
2370:   if (sdm->ops->computefunction) {
2371:     if (sdm->ops->computefunction != SNESObjectiveComputeFunctionDefaultFD) {
2372:       PetscLogEventBegin(SNES_FunctionEval,snes,x,y,0);
2373:     }
2374:     VecLockReadPush(x);
2375:     PetscStackPush("SNES user function");
2376:     /* ensure domainerror is false prior to computefunction evaluation (may not have been reset) */
2377:     snes->domainerror = PETSC_FALSE;
2378:     (*sdm->ops->computefunction)(snes,x,y,sdm->functionctx);
2379:     PetscStackPop;
2380:     VecLockReadPop(x);
2381:     if (sdm->ops->computefunction != SNESObjectiveComputeFunctionDefaultFD) {
2382:       PetscLogEventEnd(SNES_FunctionEval,snes,x,y,0);
2383:     }
2384:   } else if (snes->vec_rhs) {
2385:     MatMult(snes->jacobian, x, y);
2386:   } else SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_WRONGSTATE, "Must call SNESSetFunction() or SNESSetDM() before SNESComputeFunction(), likely called from SNESSolve().");
2387:   if (snes->vec_rhs) {
2388:     VecAXPY(y,-1.0,snes->vec_rhs);
2389:   }
2390:   snes->nfuncs++;
2391:   /*
2392:      domainerror might not be set on all processes; so we tag vector locally with Inf and the next inner product or norm will
2393:      propagate the value to all processes
2394:   */
2395:   if (snes->domainerror) {
2396:     VecSetInf(y);
2397:   }
2398:   return(0);
2399: }

2401: /*@
2402:    SNESComputeNGS - Calls the Gauss-Seidel function that has been set with  SNESSetNGS().

2404:    Collective on SNES

2406:    Input Parameters:
2407: +  snes - the SNES context
2408: .  x - input vector
2409: -  b - rhs vector

2411:    Output Parameter:
2412: .  x - new solution vector

2414:    Notes:
2415:    SNESComputeNGS() is typically used within composed nonlinear solver
2416:    implementations, so most users would not generally call this routine
2417:    themselves.

2419:    Level: developer

2421: .seealso: SNESSetNGS(), SNESComputeFunction()
2422: @*/
2423: PetscErrorCode  SNESComputeNGS(SNES snes,Vec b,Vec x)
2424: {
2426:   DM             dm;
2427:   DMSNES         sdm;

2435:   if (b) {VecValidValues(b,2,PETSC_TRUE);}
2436:   PetscLogEventBegin(SNES_NGSEval,snes,x,b,0);
2437:   SNESGetDM(snes,&dm);
2438:   DMGetDMSNES(dm,&sdm);
2439:   if (sdm->ops->computegs) {
2440:     if (b) {VecLockReadPush(b);}
2441:     PetscStackPush("SNES user NGS");
2442:     (*sdm->ops->computegs)(snes,x,b,sdm->gsctx);
2443:     PetscStackPop;
2444:     if (b) {VecLockReadPop(b);}
2445:   } else SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_WRONGSTATE, "Must call SNESSetNGS() before SNESComputeNGS(), likely called from SNESSolve().");
2446:   PetscLogEventEnd(SNES_NGSEval,snes,x,b,0);
2447:   return(0);
2448: }

2450: PetscErrorCode SNESTestJacobian(SNES snes)
2451: {
2452:   Mat               A,B,C,D,jacobian;
2453:   Vec               x = snes->vec_sol,f = snes->vec_func;
2454:   PetscErrorCode    ierr;
2455:   PetscReal         nrm,gnorm;
2456:   PetscReal         threshold = 1.e-5;
2457:   MatType           mattype;
2458:   PetscInt          m,n,M,N;
2459:   void              *functx;
2460:   PetscBool         complete_print = PETSC_FALSE,threshold_print = PETSC_FALSE,test = PETSC_FALSE,flg,istranspose;
2461:   PetscViewer       viewer,mviewer;
2462:   MPI_Comm          comm;
2463:   PetscInt          tabs;
2464:   static PetscBool  directionsprinted = PETSC_FALSE;
2465:   PetscViewerFormat format;

2468:   PetscObjectOptionsBegin((PetscObject)snes);
2469:   PetscOptionsName("-snes_test_jacobian","Compare hand-coded and finite difference Jacobians","None",&test);
2470:   PetscOptionsReal("-snes_test_jacobian", "Threshold for element difference between hand-coded and finite difference being meaningful", "None", threshold, &threshold,NULL);
2471:   PetscOptionsViewer("-snes_test_jacobian_view","View difference between hand-coded and finite difference Jacobians element entries","None",&mviewer,&format,&complete_print);
2472:   if (!complete_print) {
2473:     PetscOptionsDeprecated("-snes_test_jacobian_display","-snes_test_jacobian_view","3.13",NULL);
2474:     PetscOptionsViewer("-snes_test_jacobian_display","Display difference between hand-coded and finite difference Jacobians","None",&mviewer,&format,&complete_print);
2475:   }
2476:   /* for compatibility with PETSc 3.9 and older. */
2477:   PetscOptionsDeprecated("-snes_test_jacobian_display_threshold","-snes_test_jacobian","3.13","-snes_test_jacobian accepts an optional threshold (since v3.10)");
2478:   PetscOptionsReal("-snes_test_jacobian_display_threshold", "Display difference between hand-coded and finite difference Jacobians which exceed input threshold", "None", threshold, &threshold, &threshold_print);
2479:   PetscOptionsEnd();
2480:   if (!test) return(0);

2482:   PetscObjectGetComm((PetscObject)snes,&comm);
2483:   PetscViewerASCIIGetStdout(comm,&viewer);
2484:   PetscViewerASCIIGetTab(viewer, &tabs);
2485:   PetscViewerASCIISetTab(viewer, ((PetscObject)snes)->tablevel);
2486:   PetscViewerASCIIPrintf(viewer,"  ---------- Testing Jacobian -------------\n");
2487:   if (!complete_print && !directionsprinted) {
2488:     PetscViewerASCIIPrintf(viewer,"  Run with -snes_test_jacobian_view and optionally -snes_test_jacobian <threshold> to show difference\n");
2489:     PetscViewerASCIIPrintf(viewer,"    of hand-coded and finite difference Jacobian entries greater than <threshold>.\n");
2490:   }
2491:   if (!directionsprinted) {
2492:     PetscViewerASCIIPrintf(viewer,"  Testing hand-coded Jacobian, if (for double precision runs) ||J - Jfd||_F/||J||_F is\n");
2493:     PetscViewerASCIIPrintf(viewer,"    O(1.e-8), the hand-coded Jacobian is probably correct.\n");
2494:     directionsprinted = PETSC_TRUE;
2495:   }
2496:   if (complete_print) {
2497:     PetscViewerPushFormat(mviewer,format);
2498:   }

2500:   PetscObjectTypeCompare((PetscObject)snes->jacobian,MATMFFD,&flg);
2501:   if (!flg) jacobian = snes->jacobian;
2502:   else jacobian = snes->jacobian_pre;

2504:   if (!x) {
2505:     MatCreateVecs(jacobian, &x, NULL);
2506:   } else {
2507:     PetscObjectReference((PetscObject) x);
2508:   }
2509:   if (!f) {
2510:     VecDuplicate(x, &f);
2511:   } else {
2512:     PetscObjectReference((PetscObject) f);
2513:   }
2514:   /* evaluate the function at this point because SNESComputeJacobianDefault() assumes that the function has been evaluated and put into snes->vec_func */
2515:   SNESComputeFunction(snes,x,f);
2516:   VecDestroy(&f);
2517:   PetscObjectTypeCompare((PetscObject)snes,SNESKSPTRANSPOSEONLY,&istranspose);
2518:   while (jacobian) {
2519:     Mat JT = NULL, Jsave = NULL;

2521:     if (istranspose) {
2522:       MatCreateTranspose(jacobian,&JT);
2523:       Jsave = jacobian;
2524:       jacobian = JT;
2525:     }
2526:     PetscObjectBaseTypeCompareAny((PetscObject)jacobian,&flg,MATSEQAIJ,MATMPIAIJ,MATSEQDENSE,MATMPIDENSE,MATSEQBAIJ,MATMPIBAIJ,MATSEQSBAIJ,MATMPISBAIJ,"");
2527:     if (flg) {
2528:       A    = jacobian;
2529:       PetscObjectReference((PetscObject)A);
2530:     } else {
2531:       MatComputeOperator(jacobian,MATAIJ,&A);
2532:     }

2534:     MatGetType(A,&mattype);
2535:     MatGetSize(A,&M,&N);
2536:     MatGetLocalSize(A,&m,&n);
2537:     MatCreate(PetscObjectComm((PetscObject)A),&B);
2538:     MatSetType(B,mattype);
2539:     MatSetSizes(B,m,n,M,N);
2540:     MatSetBlockSizesFromMats(B,A,A);
2541:     MatSetUp(B);
2542:     MatSetOption(B,MAT_NEW_NONZERO_ALLOCATION_ERR,PETSC_FALSE);

2544:     SNESGetFunction(snes,NULL,NULL,&functx);
2545:     SNESComputeJacobianDefault(snes,x,B,B,functx);

2547:     MatDuplicate(B,MAT_COPY_VALUES,&D);
2548:     MatAYPX(D,-1.0,A,DIFFERENT_NONZERO_PATTERN);
2549:     MatNorm(D,NORM_FROBENIUS,&nrm);
2550:     MatNorm(A,NORM_FROBENIUS,&gnorm);
2551:     MatDestroy(&D);
2552:     if (!gnorm) gnorm = 1; /* just in case */
2553:     PetscViewerASCIIPrintf(viewer,"  ||J - Jfd||_F/||J||_F = %g, ||J - Jfd||_F = %g\n",(double)(nrm/gnorm),(double)nrm);

2555:     if (complete_print) {
2556:       PetscViewerASCIIPrintf(viewer,"  Hand-coded Jacobian ----------\n");
2557:       MatView(A,mviewer);
2558:       PetscViewerASCIIPrintf(viewer,"  Finite difference Jacobian ----------\n");
2559:       MatView(B,mviewer);
2560:     }

2562:     if (threshold_print || complete_print) {
2563:       PetscInt          Istart, Iend, *ccols, bncols, cncols, j, row;
2564:       PetscScalar       *cvals;
2565:       const PetscInt    *bcols;
2566:       const PetscScalar *bvals;

2568:       MatCreate(PetscObjectComm((PetscObject)A),&C);
2569:       MatSetType(C,mattype);
2570:       MatSetSizes(C,m,n,M,N);
2571:       MatSetBlockSizesFromMats(C,A,A);
2572:       MatSetUp(C);
2573:       MatSetOption(C,MAT_NEW_NONZERO_ALLOCATION_ERR,PETSC_FALSE);

2575:       MatAYPX(B,-1.0,A,DIFFERENT_NONZERO_PATTERN);
2576:       MatGetOwnershipRange(B,&Istart,&Iend);

2578:       for (row = Istart; row < Iend; row++) {
2579:         MatGetRow(B,row,&bncols,&bcols,&bvals);
2580:         PetscMalloc2(bncols,&ccols,bncols,&cvals);
2581:         for (j = 0, cncols = 0; j < bncols; j++) {
2582:           if (PetscAbsScalar(bvals[j]) > threshold) {
2583:             ccols[cncols] = bcols[j];
2584:             cvals[cncols] = bvals[j];
2585:             cncols += 1;
2586:           }
2587:         }
2588:         if (cncols) {
2589:           MatSetValues(C,1,&row,cncols,ccols,cvals,INSERT_VALUES);
2590:         }
2591:         MatRestoreRow(B,row,&bncols,&bcols,&bvals);
2592:         PetscFree2(ccols,cvals);
2593:       }
2594:       MatAssemblyBegin(C,MAT_FINAL_ASSEMBLY);
2595:       MatAssemblyEnd(C,MAT_FINAL_ASSEMBLY);
2596:       PetscViewerASCIIPrintf(viewer,"  Hand-coded minus finite-difference Jacobian with tolerance %g ----------\n",(double)threshold);
2597:       MatView(C,complete_print ? mviewer : viewer);
2598:       MatDestroy(&C);
2599:     }
2600:     MatDestroy(&A);
2601:     MatDestroy(&B);
2602:     MatDestroy(&JT);
2603:     if (Jsave) jacobian = Jsave;
2604:     if (jacobian != snes->jacobian_pre) {
2605:       jacobian = snes->jacobian_pre;
2606:       PetscViewerASCIIPrintf(viewer,"  ---------- Testing Jacobian for preconditioner -------------\n");
2607:     }
2608:     else jacobian = NULL;
2609:   }
2610:   VecDestroy(&x);
2611:   if (complete_print) {
2612:     PetscViewerPopFormat(mviewer);
2613:   }
2614:   if (mviewer) { PetscViewerDestroy(&mviewer); }
2615:   PetscViewerASCIISetTab(viewer,tabs);
2616:   return(0);
2617: }

2619: /*@
2620:    SNESComputeJacobian - Computes the Jacobian matrix that has been set with SNESSetJacobian().

2622:    Collective on SNES

2624:    Input Parameters:
2625: +  snes - the SNES context
2626: -  x - input vector

2628:    Output Parameters:
2629: +  A - Jacobian matrix
2630: -  B - optional preconditioning matrix

2632:   Options Database Keys:
2633: +    -snes_lag_preconditioner <lag>
2634: .    -snes_lag_jacobian <lag>
2635: .    -snes_test_jacobian <optional threshold> - compare the user provided Jacobian with one compute via finite differences to check for errors.  If a threshold is given, display only those entries whose difference is greater than the threshold.
2636: .    -snes_test_jacobian_view - display the user provided Jacobian, the finite difference Jacobian and the difference between them to help users detect the location of errors in the user provided Jacobian
2637: .    -snes_compare_explicit - Compare the computed Jacobian to the finite difference Jacobian and output the differences
2638: .    -snes_compare_explicit_draw  - Compare the computed Jacobian to the finite difference Jacobian and draw the result
2639: .    -snes_compare_explicit_contour  - Compare the computed Jacobian to the finite difference Jacobian and draw a contour plot with the result
2640: .    -snes_compare_operator  - Make the comparison options above use the operator instead of the preconditioning matrix
2641: .    -snes_compare_coloring - Compute the finite difference Jacobian using coloring and display norms of difference
2642: .    -snes_compare_coloring_display - Compute the finite differece Jacobian using coloring and display verbose differences
2643: .    -snes_compare_coloring_threshold - Display only those matrix entries that differ by more than a given threshold
2644: .    -snes_compare_coloring_threshold_atol - Absolute tolerance for difference in matrix entries to be displayed by -snes_compare_coloring_threshold
2645: .    -snes_compare_coloring_threshold_rtol - Relative tolerance for difference in matrix entries to be displayed by -snes_compare_coloring_threshold
2646: .    -snes_compare_coloring_draw - Compute the finite differece Jacobian using coloring and draw differences
2647: -    -snes_compare_coloring_draw_contour - Compute the finite differece Jacobian using coloring and show contours of matrices and differences


2650:    Notes:
2651:    Most users should not need to explicitly call this routine, as it
2652:    is used internally within the nonlinear solvers.

2654:    Developer Notes:
2655:     This has duplicative ways of checking the accuracy of the user provided Jacobian (see the options above). This is for historical reasons, the routine SNESTestJacobian() use to used
2656:       for with the SNESType of test that has been removed.

2658:    Level: developer

2660: .seealso:  SNESSetJacobian(), KSPSetOperators(), MatStructure, SNESSetLagPreconditioner(), SNESSetLagJacobian()
2661: @*/
2662: PetscErrorCode  SNESComputeJacobian(SNES snes,Vec X,Mat A,Mat B)
2663: {
2665:   PetscBool      flag;
2666:   DM             dm;
2667:   DMSNES         sdm;
2668:   KSP            ksp;

2674:   VecValidValues(X,2,PETSC_TRUE);
2675:   SNESGetDM(snes,&dm);
2676:   DMGetDMSNES(dm,&sdm);

2678:   if (!sdm->ops->computejacobian) SETERRQ(PetscObjectComm((PetscObject)snes),PETSC_ERR_USER,"Must call SNESSetJacobian(), DMSNESSetJacobian(), DMDASNESSetJacobianLocal(), etc");

2680:   /* make sure that MatAssemblyBegin/End() is called on A matrix if it is matrix free */

2682:   if (snes->lagjacobian == -2) {
2683:     snes->lagjacobian = -1;

2685:     PetscInfo(snes,"Recomputing Jacobian/preconditioner because lag is -2 (means compute Jacobian, but then never again) \n");
2686:   } else if (snes->lagjacobian == -1) {
2687:     PetscInfo(snes,"Reusing Jacobian/preconditioner because lag is -1\n");
2688:     PetscObjectTypeCompare((PetscObject)A,MATMFFD,&flag);
2689:     if (flag) {
2690:       MatAssemblyBegin(A,MAT_FINAL_ASSEMBLY);
2691:       MatAssemblyEnd(A,MAT_FINAL_ASSEMBLY);
2692:     }
2693:     return(0);
2694:   } else if (snes->lagjacobian > 1 && (snes->iter + snes->jac_iter) % snes->lagjacobian) {
2695:     PetscInfo2(snes,"Reusing Jacobian/preconditioner because lag is %D and SNES iteration is %D\n",snes->lagjacobian,snes->iter);
2696:     PetscObjectTypeCompare((PetscObject)A,MATMFFD,&flag);
2697:     if (flag) {
2698:       MatAssemblyBegin(A,MAT_FINAL_ASSEMBLY);
2699:       MatAssemblyEnd(A,MAT_FINAL_ASSEMBLY);
2700:     }
2701:     return(0);
2702:   }
2703:   if (snes->npc && snes->npcside== PC_LEFT) {
2704:     MatAssemblyBegin(A,MAT_FINAL_ASSEMBLY);
2705:     MatAssemblyEnd(A,MAT_FINAL_ASSEMBLY);
2706:     return(0);
2707:   }

2709:   PetscLogEventBegin(SNES_JacobianEval,snes,X,A,B);
2710:   VecLockReadPush(X);
2711:   PetscStackPush("SNES user Jacobian function");
2712:   (*sdm->ops->computejacobian)(snes,X,A,B,sdm->jacobianctx);
2713:   PetscStackPop;
2714:   VecLockReadPop(X);
2715:   PetscLogEventEnd(SNES_JacobianEval,snes,X,A,B);

2717:   /* attach latest linearization point to the preconditioning matrix */
2718:   PetscObjectCompose((PetscObject)B,"__SNES_latest_X",(PetscObject)X);

2720:   /* the next line ensures that snes->ksp exists */
2721:   SNESGetKSP(snes,&ksp);
2722:   if (snes->lagpreconditioner == -2) {
2723:     PetscInfo(snes,"Rebuilding preconditioner exactly once since lag is -2\n");
2724:     KSPSetReusePreconditioner(snes->ksp,PETSC_FALSE);
2725:     snes->lagpreconditioner = -1;
2726:   } else if (snes->lagpreconditioner == -1) {
2727:     PetscInfo(snes,"Reusing preconditioner because lag is -1\n");
2728:     KSPSetReusePreconditioner(snes->ksp,PETSC_TRUE);
2729:   } else if (snes->lagpreconditioner > 1 && (snes->iter + snes->pre_iter) % snes->lagpreconditioner) {
2730:     PetscInfo2(snes,"Reusing preconditioner because lag is %D and SNES iteration is %D\n",snes->lagpreconditioner,snes->iter);
2731:     KSPSetReusePreconditioner(snes->ksp,PETSC_TRUE);
2732:   } else {
2733:     PetscInfo(snes,"Rebuilding preconditioner\n");
2734:     KSPSetReusePreconditioner(snes->ksp,PETSC_FALSE);
2735:   }

2737:   SNESTestJacobian(snes);
2738:   /* make sure user returned a correct Jacobian and preconditioner */
2741:   {
2742:     PetscBool flag = PETSC_FALSE,flag_draw = PETSC_FALSE,flag_contour = PETSC_FALSE,flag_operator = PETSC_FALSE;
2743:     PetscOptionsGetViewer(PetscObjectComm((PetscObject)snes),((PetscObject) snes)->options,((PetscObject)snes)->prefix,"-snes_compare_explicit",NULL,NULL,&flag);
2744:     PetscOptionsGetViewer(PetscObjectComm((PetscObject)snes),((PetscObject) snes)->options,((PetscObject)snes)->prefix,"-snes_compare_explicit_draw",NULL,NULL,&flag_draw);
2745:     PetscOptionsGetViewer(PetscObjectComm((PetscObject)snes),((PetscObject) snes)->options,((PetscObject)snes)->prefix,"-snes_compare_explicit_draw_contour",NULL,NULL,&flag_contour);
2746:     PetscOptionsGetViewer(PetscObjectComm((PetscObject)snes),((PetscObject) snes)->options,((PetscObject)snes)->prefix,"-snes_compare_operator",NULL,NULL,&flag_operator);
2747:     if (flag || flag_draw || flag_contour) {
2748:       Mat          Bexp_mine = NULL,Bexp,FDexp;
2749:       PetscViewer  vdraw,vstdout;
2750:       PetscBool    flg;
2751:       if (flag_operator) {
2752:         MatComputeOperator(A,MATAIJ,&Bexp_mine);
2753:         Bexp = Bexp_mine;
2754:       } else {
2755:         /* See if the preconditioning matrix can be viewed and added directly */
2756:         PetscObjectBaseTypeCompareAny((PetscObject)B,&flg,MATSEQAIJ,MATMPIAIJ,MATSEQDENSE,MATMPIDENSE,MATSEQBAIJ,MATMPIBAIJ,MATSEQSBAIJ,MATMPIBAIJ,"");
2757:         if (flg) Bexp = B;
2758:         else {
2759:           /* If the "preconditioning" matrix is itself MATSHELL or some other type without direct support */
2760:           MatComputeOperator(B,MATAIJ,&Bexp_mine);
2761:           Bexp = Bexp_mine;
2762:         }
2763:       }
2764:       MatConvert(Bexp,MATSAME,MAT_INITIAL_MATRIX,&FDexp);
2765:       SNESComputeJacobianDefault(snes,X,FDexp,FDexp,NULL);
2766:       PetscViewerASCIIGetStdout(PetscObjectComm((PetscObject)snes),&vstdout);
2767:       if (flag_draw || flag_contour) {
2768:         PetscViewerDrawOpen(PetscObjectComm((PetscObject)snes),NULL,"Explicit Jacobians",PETSC_DECIDE,PETSC_DECIDE,300,300,&vdraw);
2769:         if (flag_contour) {PetscViewerPushFormat(vdraw,PETSC_VIEWER_DRAW_CONTOUR);}
2770:       } else vdraw = NULL;
2771:       PetscViewerASCIIPrintf(vstdout,"Explicit %s\n",flag_operator ? "Jacobian" : "preconditioning Jacobian");
2772:       if (flag) {MatView(Bexp,vstdout);}
2773:       if (vdraw) {MatView(Bexp,vdraw);}
2774:       PetscViewerASCIIPrintf(vstdout,"Finite difference Jacobian\n");
2775:       if (flag) {MatView(FDexp,vstdout);}
2776:       if (vdraw) {MatView(FDexp,vdraw);}
2777:       MatAYPX(FDexp,-1.0,Bexp,SAME_NONZERO_PATTERN);
2778:       PetscViewerASCIIPrintf(vstdout,"User-provided matrix minus finite difference Jacobian\n");
2779:       if (flag) {MatView(FDexp,vstdout);}
2780:       if (vdraw) {              /* Always use contour for the difference */
2781:         PetscViewerPushFormat(vdraw,PETSC_VIEWER_DRAW_CONTOUR);
2782:         MatView(FDexp,vdraw);
2783:         PetscViewerPopFormat(vdraw);
2784:       }
2785:       if (flag_contour) {PetscViewerPopFormat(vdraw);}
2786:       PetscViewerDestroy(&vdraw);
2787:       MatDestroy(&Bexp_mine);
2788:       MatDestroy(&FDexp);
2789:     }
2790:   }
2791:   {
2792:     PetscBool flag = PETSC_FALSE,flag_display = PETSC_FALSE,flag_draw = PETSC_FALSE,flag_contour = PETSC_FALSE,flag_threshold = PETSC_FALSE;
2793:     PetscReal threshold_atol = PETSC_SQRT_MACHINE_EPSILON,threshold_rtol = 10*PETSC_SQRT_MACHINE_EPSILON;
2794:     PetscOptionsGetViewer(PetscObjectComm((PetscObject)snes),((PetscObject)snes)->options,((PetscObject)snes)->prefix,"-snes_compare_coloring",NULL,NULL,&flag);
2795:     PetscOptionsGetViewer(PetscObjectComm((PetscObject)snes),((PetscObject)snes)->options,((PetscObject)snes)->prefix,"-snes_compare_coloring_display",NULL,NULL,&flag_display);
2796:     PetscOptionsGetViewer(PetscObjectComm((PetscObject)snes),((PetscObject)snes)->options,((PetscObject)snes)->prefix,"-snes_compare_coloring_draw",NULL,NULL,&flag_draw);
2797:     PetscOptionsGetViewer(PetscObjectComm((PetscObject)snes),((PetscObject)snes)->options,((PetscObject)snes)->prefix,"-snes_compare_coloring_draw_contour",NULL,NULL,&flag_contour);
2798:     PetscOptionsGetViewer(PetscObjectComm((PetscObject)snes),((PetscObject)snes)->options,((PetscObject)snes)->prefix,"-snes_compare_coloring_threshold",NULL,NULL,&flag_threshold);
2799:     if (flag_threshold) {
2800:       PetscOptionsGetReal(((PetscObject)snes)->options,((PetscObject)snes)->prefix,"-snes_compare_coloring_threshold_rtol",&threshold_rtol,NULL);
2801:       PetscOptionsGetReal(((PetscObject)snes)->options,((PetscObject)snes)->prefix,"-snes_compare_coloring_threshold_atol",&threshold_atol,NULL);
2802:     }
2803:     if (flag || flag_display || flag_draw || flag_contour || flag_threshold) {
2804:       Mat            Bfd;
2805:       PetscViewer    vdraw,vstdout;
2806:       MatColoring    coloring;
2807:       ISColoring     iscoloring;
2808:       MatFDColoring  matfdcoloring;
2809:       PetscErrorCode (*func)(SNES,Vec,Vec,void*);
2810:       void           *funcctx;
2811:       PetscReal      norm1,norm2,normmax;

2813:       MatDuplicate(B,MAT_DO_NOT_COPY_VALUES,&Bfd);
2814:       MatColoringCreate(Bfd,&coloring);
2815:       MatColoringSetType(coloring,MATCOLORINGSL);
2816:       MatColoringSetFromOptions(coloring);
2817:       MatColoringApply(coloring,&iscoloring);
2818:       MatColoringDestroy(&coloring);
2819:       MatFDColoringCreate(Bfd,iscoloring,&matfdcoloring);
2820:       MatFDColoringSetFromOptions(matfdcoloring);
2821:       MatFDColoringSetUp(Bfd,iscoloring,matfdcoloring);
2822:       ISColoringDestroy(&iscoloring);

2824:       /* This method of getting the function is currently unreliable since it doesn't work for DM local functions. */
2825:       SNESGetFunction(snes,NULL,&func,&funcctx);
2826:       MatFDColoringSetFunction(matfdcoloring,(PetscErrorCode (*)(void))func,funcctx);
2827:       PetscObjectSetOptionsPrefix((PetscObject)matfdcoloring,((PetscObject)snes)->prefix);
2828:       PetscObjectAppendOptionsPrefix((PetscObject)matfdcoloring,"coloring_");
2829:       MatFDColoringSetFromOptions(matfdcoloring);
2830:       MatFDColoringApply(Bfd,matfdcoloring,X,snes);
2831:       MatFDColoringDestroy(&matfdcoloring);

2833:       PetscViewerASCIIGetStdout(PetscObjectComm((PetscObject)snes),&vstdout);
2834:       if (flag_draw || flag_contour) {
2835:         PetscViewerDrawOpen(PetscObjectComm((PetscObject)snes),NULL,"Colored Jacobians",PETSC_DECIDE,PETSC_DECIDE,300,300,&vdraw);
2836:         if (flag_contour) {PetscViewerPushFormat(vdraw,PETSC_VIEWER_DRAW_CONTOUR);}
2837:       } else vdraw = NULL;
2838:       PetscViewerASCIIPrintf(vstdout,"Explicit preconditioning Jacobian\n");
2839:       if (flag_display) {MatView(B,vstdout);}
2840:       if (vdraw) {MatView(B,vdraw);}
2841:       PetscViewerASCIIPrintf(vstdout,"Colored Finite difference Jacobian\n");
2842:       if (flag_display) {MatView(Bfd,vstdout);}
2843:       if (vdraw) {MatView(Bfd,vdraw);}
2844:       MatAYPX(Bfd,-1.0,B,SAME_NONZERO_PATTERN);
2845:       MatNorm(Bfd,NORM_1,&norm1);
2846:       MatNorm(Bfd,NORM_FROBENIUS,&norm2);
2847:       MatNorm(Bfd,NORM_MAX,&normmax);
2848:       PetscViewerASCIIPrintf(vstdout,"User-provided matrix minus finite difference Jacobian, norm1=%g normFrob=%g normmax=%g\n",(double)norm1,(double)norm2,(double)normmax);
2849:       if (flag_display) {MatView(Bfd,vstdout);}
2850:       if (vdraw) {              /* Always use contour for the difference */
2851:         PetscViewerPushFormat(vdraw,PETSC_VIEWER_DRAW_CONTOUR);
2852:         MatView(Bfd,vdraw);
2853:         PetscViewerPopFormat(vdraw);
2854:       }
2855:       if (flag_contour) {PetscViewerPopFormat(vdraw);}

2857:       if (flag_threshold) {
2858:         PetscInt bs,rstart,rend,i;
2859:         MatGetBlockSize(B,&bs);
2860:         MatGetOwnershipRange(B,&rstart,&rend);
2861:         for (i=rstart; i<rend; i++) {
2862:           const PetscScalar *ba,*ca;
2863:           const PetscInt    *bj,*cj;
2864:           PetscInt          bn,cn,j,maxentrycol = -1,maxdiffcol = -1,maxrdiffcol = -1;
2865:           PetscReal         maxentry = 0,maxdiff = 0,maxrdiff = 0;
2866:           MatGetRow(B,i,&bn,&bj,&ba);
2867:           MatGetRow(Bfd,i,&cn,&cj,&ca);
2868:           if (bn != cn) SETERRQ(((PetscObject)A)->comm,PETSC_ERR_PLIB,"Unexpected different nonzero pattern in -snes_compare_coloring_threshold");
2869:           for (j=0; j<bn; j++) {
2870:             PetscReal rdiff = PetscAbsScalar(ca[j]) / (threshold_atol + threshold_rtol*PetscAbsScalar(ba[j]));
2871:             if (PetscAbsScalar(ba[j]) > PetscAbs(maxentry)) {
2872:               maxentrycol = bj[j];
2873:               maxentry    = PetscRealPart(ba[j]);
2874:             }
2875:             if (PetscAbsScalar(ca[j]) > PetscAbs(maxdiff)) {
2876:               maxdiffcol = bj[j];
2877:               maxdiff    = PetscRealPart(ca[j]);
2878:             }
2879:             if (rdiff > maxrdiff) {
2880:               maxrdiffcol = bj[j];
2881:               maxrdiff    = rdiff;
2882:             }
2883:           }
2884:           if (maxrdiff > 1) {
2885:             PetscViewerASCIIPrintf(vstdout,"row %D (maxentry=%g at %D, maxdiff=%g at %D, maxrdiff=%g at %D):",i,(double)maxentry,maxentrycol,(double)maxdiff,maxdiffcol,(double)maxrdiff,maxrdiffcol);
2886:             for (j=0; j<bn; j++) {
2887:               PetscReal rdiff;
2888:               rdiff = PetscAbsScalar(ca[j]) / (threshold_atol + threshold_rtol*PetscAbsScalar(ba[j]));
2889:               if (rdiff > 1) {
2890:                 PetscViewerASCIIPrintf(vstdout," (%D,%g:%g)",bj[j],(double)PetscRealPart(ba[j]),(double)PetscRealPart(ca[j]));
2891:               }
2892:             }
2893:             PetscViewerASCIIPrintf(vstdout,"\n",i,maxentry,maxdiff,maxrdiff);
2894:           }
2895:           MatRestoreRow(B,i,&bn,&bj,&ba);
2896:           MatRestoreRow(Bfd,i,&cn,&cj,&ca);
2897:         }
2898:       }
2899:       PetscViewerDestroy(&vdraw);
2900:       MatDestroy(&Bfd);
2901:     }
2902:   }
2903:   return(0);
2904: }

2906: /*MC
2907:     SNESJacobianFunction - Function used to convey the nonlinear Jacobian of the function to be solved by SNES

2909:      Synopsis:
2910:      #include "petscsnes.h"
2911:      PetscErrorCode SNESJacobianFunction(SNES snes,Vec x,Mat Amat,Mat Pmat,void *ctx);

2913:      Collective on snes

2915:     Input Parameters:
2916: +  x - input vector, the Jacobian is to be computed at this value
2917: -  ctx - [optional] user-defined Jacobian context

2919:     Output Parameters:
2920: +  Amat - the matrix that defines the (approximate) Jacobian
2921: -  Pmat - the matrix to be used in constructing the preconditioner, usually the same as Amat.

2923:    Level: intermediate

2925: .seealso:   SNESSetFunction(), SNESGetFunction(), SNESSetJacobian(), SNESGetJacobian()
2926: M*/

2928: /*@C
2929:    SNESSetJacobian - Sets the function to compute Jacobian as well as the
2930:    location to store the matrix.

2932:    Logically Collective on SNES

2934:    Input Parameters:
2935: +  snes - the SNES context
2936: .  Amat - the matrix that defines the (approximate) Jacobian
2937: .  Pmat - the matrix to be used in constructing the preconditioner, usually the same as Amat.
2938: .  J - Jacobian evaluation routine (if NULL then SNES retains any previously set value), see SNESJacobianFunction for details
2939: -  ctx - [optional] user-defined context for private data for the
2940:          Jacobian evaluation routine (may be NULL) (if NULL then SNES retains any previously set value)

2942:    Notes:
2943:    If the Amat matrix and Pmat matrix are different you must call MatAssemblyBegin/End() on
2944:    each matrix.

2946:    If you know the operator Amat has a null space you can use MatSetNullSpace() and MatSetTransposeNullSpace() to supply the null
2947:    space to Amat and the KSP solvers will automatically use that null space as needed during the solution process.

2949:    If using SNESComputeJacobianDefaultColor() to assemble a Jacobian, the ctx argument
2950:    must be a MatFDColoring.

2952:    Other defect-correction schemes can be used by computing a different matrix in place of the Jacobian.  One common
2953:    example is to use the "Picard linearization" which only differentiates through the highest order parts of each term.

2955:    Level: beginner

2957: .seealso: KSPSetOperators(), SNESSetFunction(), MatMFFDComputeJacobian(), SNESComputeJacobianDefaultColor(), MatStructure, J,
2958:           SNESSetPicard(), SNESJacobianFunction
2959: @*/
2960: PetscErrorCode  SNESSetJacobian(SNES snes,Mat Amat,Mat Pmat,PetscErrorCode (*J)(SNES,Vec,Mat,Mat,void*),void *ctx)
2961: {
2963:   DM             dm;

2971:   SNESGetDM(snes,&dm);
2972:   DMSNESSetJacobian(dm,J,ctx);
2973:   if (Amat) {
2974:     PetscObjectReference((PetscObject)Amat);
2975:     MatDestroy(&snes->jacobian);

2977:     snes->jacobian = Amat;
2978:   }
2979:   if (Pmat) {
2980:     PetscObjectReference((PetscObject)Pmat);
2981:     MatDestroy(&snes->jacobian_pre);

2983:     snes->jacobian_pre = Pmat;
2984:   }
2985:   return(0);
2986: }

2988: /*@C
2989:    SNESGetJacobian - Returns the Jacobian matrix and optionally the user
2990:    provided context for evaluating the Jacobian.

2992:    Not Collective, but Mat object will be parallel if SNES object is

2994:    Input Parameter:
2995: .  snes - the nonlinear solver context

2997:    Output Parameters:
2998: +  Amat - location to stash (approximate) Jacobian matrix (or NULL)
2999: .  Pmat - location to stash matrix used to compute the preconditioner (or NULL)
3000: .  J - location to put Jacobian function (or NULL), see SNESJacobianFunction for details on its calling sequence
3001: -  ctx - location to stash Jacobian ctx (or NULL)

3003:    Level: advanced

3005: .seealso: SNESSetJacobian(), SNESComputeJacobian(), SNESJacobianFunction, SNESGetFunction()
3006: @*/
3007: PetscErrorCode SNESGetJacobian(SNES snes,Mat *Amat,Mat *Pmat,PetscErrorCode (**J)(SNES,Vec,Mat,Mat,void*),void **ctx)
3008: {
3010:   DM             dm;
3011:   DMSNES         sdm;

3015:   if (Amat) *Amat = snes->jacobian;
3016:   if (Pmat) *Pmat = snes->jacobian_pre;
3017:   SNESGetDM(snes,&dm);
3018:   DMGetDMSNES(dm,&sdm);
3019:   if (J) *J = sdm->ops->computejacobian;
3020:   if (ctx) *ctx = sdm->jacobianctx;
3021:   return(0);
3022: }

3024: /*@
3025:    SNESSetUp - Sets up the internal data structures for the later use
3026:    of a nonlinear solver.

3028:    Collective on SNES

3030:    Input Parameters:
3031: .  snes - the SNES context

3033:    Notes:
3034:    For basic use of the SNES solvers the user need not explicitly call
3035:    SNESSetUp(), since these actions will automatically occur during
3036:    the call to SNESSolve().  However, if one wishes to control this
3037:    phase separately, SNESSetUp() should be called after SNESCreate()
3038:    and optional routines of the form SNESSetXXX(), but before SNESSolve().

3040:    Level: advanced

3042: .seealso: SNESCreate(), SNESSolve(), SNESDestroy()
3043: @*/
3044: PetscErrorCode  SNESSetUp(SNES snes)
3045: {
3047:   DM             dm;
3048:   DMSNES         sdm;
3049:   SNESLineSearch linesearch, pclinesearch;
3050:   void           *lsprectx,*lspostctx;
3051:   PetscErrorCode (*precheck)(SNESLineSearch,Vec,Vec,PetscBool*,void*);
3052:   PetscErrorCode (*postcheck)(SNESLineSearch,Vec,Vec,Vec,PetscBool*,PetscBool*,void*);
3053:   PetscErrorCode (*func)(SNES,Vec,Vec,void*);
3054:   Vec            f,fpc;
3055:   void           *funcctx;
3056:   PetscErrorCode (*jac)(SNES,Vec,Mat,Mat,void*);
3057:   void           *jacctx,*appctx;
3058:   Mat            j,jpre;

3062:   if (snes->setupcalled) return(0);
3063:   PetscLogEventBegin(SNES_Setup,snes,0,0,0);

3065:   if (!((PetscObject)snes)->type_name) {
3066:     SNESSetType(snes,SNESNEWTONLS);
3067:   }

3069:   SNESGetFunction(snes,&snes->vec_func,NULL,NULL);

3071:   SNESGetDM(snes,&dm);
3072:   DMGetDMSNES(dm,&sdm);
3073:   if (!sdm->ops->computefunction) SETERRQ(PetscObjectComm((PetscObject)dm),PETSC_ERR_ARG_WRONGSTATE,"Function never provided to SNES object");
3074:   if (!sdm->ops->computejacobian) {
3075:     DMSNESSetJacobian(dm,SNESComputeJacobianDefaultColor,NULL);
3076:   }
3077:   if (!snes->vec_func) {
3078:     DMCreateGlobalVector(dm,&snes->vec_func);
3079:   }

3081:   if (!snes->ksp) {
3082:     SNESGetKSP(snes, &snes->ksp);
3083:   }

3085:   if (snes->linesearch) {
3086:     SNESGetLineSearch(snes, &snes->linesearch);
3087:     SNESLineSearchSetFunction(snes->linesearch,SNESComputeFunction);
3088:   }

3090:   if (snes->npc && (snes->npcside== PC_LEFT)) {
3091:     snes->mf          = PETSC_TRUE;
3092:     snes->mf_operator = PETSC_FALSE;
3093:   }

3095:   if (snes->npc) {
3096:     /* copy the DM over */
3097:     SNESGetDM(snes,&dm);
3098:     SNESSetDM(snes->npc,dm);

3100:     SNESGetFunction(snes,&f,&func,&funcctx);
3101:     VecDuplicate(f,&fpc);
3102:     SNESSetFunction(snes->npc,fpc,func,funcctx);
3103:     SNESGetJacobian(snes,&j,&jpre,&jac,&jacctx);
3104:     SNESSetJacobian(snes->npc,j,jpre,jac,jacctx);
3105:     SNESGetApplicationContext(snes,&appctx);
3106:     SNESSetApplicationContext(snes->npc,appctx);
3107:     VecDestroy(&fpc);

3109:     /* copy the function pointers over */
3110:     PetscObjectCopyFortranFunctionPointers((PetscObject)snes,(PetscObject)snes->npc);

3112:     /* default to 1 iteration */
3113:     SNESSetTolerances(snes->npc,0.0,0.0,0.0,1,snes->npc->max_funcs);
3114:     if (snes->npcside==PC_RIGHT) {
3115:       SNESSetNormSchedule(snes->npc,SNES_NORM_FINAL_ONLY);
3116:     } else {
3117:       SNESSetNormSchedule(snes->npc,SNES_NORM_NONE);
3118:     }
3119:     SNESSetFromOptions(snes->npc);

3121:     /* copy the line search context over */
3122:     if (snes->linesearch && snes->npc->linesearch) {
3123:       SNESGetLineSearch(snes,&linesearch);
3124:       SNESGetLineSearch(snes->npc,&pclinesearch);
3125:       SNESLineSearchGetPreCheck(linesearch,&precheck,&lsprectx);
3126:       SNESLineSearchGetPostCheck(linesearch,&postcheck,&lspostctx);
3127:       SNESLineSearchSetPreCheck(pclinesearch,precheck,lsprectx);
3128:       SNESLineSearchSetPostCheck(pclinesearch,postcheck,lspostctx);
3129:       PetscObjectCopyFortranFunctionPointers((PetscObject)linesearch, (PetscObject)pclinesearch);
3130:     }
3131:   }
3132:   if (snes->mf) {
3133:     SNESSetUpMatrixFree_Private(snes, snes->mf_operator, snes->mf_version);
3134:   }
3135:   if (snes->ops->usercompute && !snes->user) {
3136:     (*snes->ops->usercompute)(snes,(void**)&snes->user);
3137:   }

3139:   snes->jac_iter = 0;
3140:   snes->pre_iter = 0;

3142:   if (snes->ops->setup) {
3143:     (*snes->ops->setup)(snes);
3144:   }

3146:   if (snes->npc && (snes->npcside== PC_LEFT)) {
3147:     if (snes->functype == SNES_FUNCTION_PRECONDITIONED) {
3148:       if (snes->linesearch){
3149:         SNESGetLineSearch(snes,&linesearch);
3150:         SNESLineSearchSetFunction(linesearch,SNESComputeFunctionDefaultNPC);
3151:       }
3152:     }
3153:   }
3154:   PetscLogEventEnd(SNES_Setup,snes,0,0,0);
3155:   snes->setupcalled = PETSC_TRUE;
3156:   return(0);
3157: }

3159: /*@
3160:    SNESReset - Resets a SNES context to the snessetupcalled = 0 state and removes any allocated Vecs and Mats

3162:    Collective on SNES

3164:    Input Parameter:
3165: .  snes - iterative context obtained from SNESCreate()

3167:    Level: intermediate

3169:    Notes:
3170:     Also calls the Section 1.5 Writing Application Codes with PETSc context destroy routine set with SNESSetComputeApplicationContext()

3172: .seealso: SNESCreate(), SNESSetUp(), SNESSolve()
3173: @*/
3174: PetscErrorCode  SNESReset(SNES snes)
3175: {

3180:   if (snes->ops->userdestroy && snes->user) {
3181:     (*snes->ops->userdestroy)((void**)&snes->user);
3182:     snes->user = NULL;
3183:   }
3184:   if (snes->npc) {
3185:     SNESReset(snes->npc);
3186:   }

3188:   if (snes->ops->reset) {
3189:     (*snes->ops->reset)(snes);
3190:   }
3191:   if (snes->ksp) {
3192:     KSPReset(snes->ksp);
3193:   }

3195:   if (snes->linesearch) {
3196:     SNESLineSearchReset(snes->linesearch);
3197:   }

3199:   VecDestroy(&snes->vec_rhs);
3200:   VecDestroy(&snes->vec_sol);
3201:   VecDestroy(&snes->vec_sol_update);
3202:   VecDestroy(&snes->vec_func);
3203:   MatDestroy(&snes->jacobian);
3204:   MatDestroy(&snes->jacobian_pre);
3205:   VecDestroyVecs(snes->nwork,&snes->work);
3206:   VecDestroyVecs(snes->nvwork,&snes->vwork);

3208:   snes->alwayscomputesfinalresidual = PETSC_FALSE;

3210:   snes->nwork       = snes->nvwork = 0;
3211:   snes->setupcalled = PETSC_FALSE;
3212:   return(0);
3213: }

3215: /*@
3216:    SNESDestroy - Destroys the nonlinear solver context that was created
3217:    with SNESCreate().

3219:    Collective on SNES

3221:    Input Parameter:
3222: .  snes - the SNES context

3224:    Level: beginner

3226: .seealso: SNESCreate(), SNESSolve()
3227: @*/
3228: PetscErrorCode  SNESDestroy(SNES *snes)
3229: {

3233:   if (!*snes) return(0);
3235:   if (--((PetscObject)(*snes))->refct > 0) {*snes = NULL; return(0);}

3237:   SNESReset((*snes));
3238:   SNESDestroy(&(*snes)->npc);

3240:   /* if memory was published with SAWs then destroy it */
3241:   PetscObjectSAWsViewOff((PetscObject)*snes);
3242:   if ((*snes)->ops->destroy) {(*((*snes))->ops->destroy)((*snes));}

3244:   if ((*snes)->dm) {DMCoarsenHookRemove((*snes)->dm,DMCoarsenHook_SNESVecSol,DMRestrictHook_SNESVecSol,*snes);}
3245:   DMDestroy(&(*snes)->dm);
3246:   KSPDestroy(&(*snes)->ksp);
3247:   SNESLineSearchDestroy(&(*snes)->linesearch);

3249:   PetscFree((*snes)->kspconvctx);
3250:   if ((*snes)->ops->convergeddestroy) {
3251:     (*(*snes)->ops->convergeddestroy)((*snes)->cnvP);
3252:   }
3253:   if ((*snes)->conv_hist_alloc) {
3254:     PetscFree2((*snes)->conv_hist,(*snes)->conv_hist_its);
3255:   }
3256:   SNESMonitorCancel((*snes));
3257:   PetscHeaderDestroy(snes);
3258:   return(0);
3259: }

3261: /* ----------- Routines to set solver parameters ---------- */

3263: /*@
3264:    SNESSetLagPreconditioner - Determines when the preconditioner is rebuilt in the nonlinear solve.

3266:    Logically Collective on SNES

3268:    Input Parameters:
3269: +  snes - the SNES context
3270: -  lag - -1 indicates NEVER rebuild, 1 means rebuild every time the Jacobian is computed within a single nonlinear solve, 2 means every second time
3271:          the Jacobian is built etc. -2 indicates rebuild preconditioner at next chance but then never rebuild after that

3273:    Options Database Keys:
3274: .    -snes_lag_preconditioner <lag>

3276:    Notes:
3277:    The default is 1
3278:    The preconditioner is ALWAYS built in the first iteration of a nonlinear solve unless lag is -1
3279:    If  -1 is used before the very first nonlinear solve the preconditioner is still built because there is no previous preconditioner to use

3281:    Level: intermediate

3283: .seealso: SNESSetTrustRegionTolerance(), SNESGetLagPreconditioner(), SNESSetLagJacobian(), SNESGetLagJacobian()

3285: @*/
3286: PetscErrorCode  SNESSetLagPreconditioner(SNES snes,PetscInt lag)
3287: {
3290:   if (lag < -2) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"Lag must be -2, -1, 1 or greater");
3291:   if (!lag) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"Lag cannot be 0");
3293:   snes->lagpreconditioner = lag;
3294:   return(0);
3295: }

3297: /*@
3298:    SNESSetGridSequence - sets the number of steps of grid sequencing that SNES does

3300:    Logically Collective on SNES

3302:    Input Parameters:
3303: +  snes - the SNES context
3304: -  steps - the number of refinements to do, defaults to 0

3306:    Options Database Keys:
3307: .    -snes_grid_sequence <steps>

3309:    Level: intermediate

3311:    Notes:
3312:    Use SNESGetSolution() to extract the fine grid solution after grid sequencing.

3314: .seealso: SNESSetTrustRegionTolerance(), SNESGetLagPreconditioner(), SNESSetLagJacobian(), SNESGetLagJacobian(), SNESGetGridSequence()

3316: @*/
3317: PetscErrorCode  SNESSetGridSequence(SNES snes,PetscInt steps)
3318: {
3322:   snes->gridsequence = steps;
3323:   return(0);
3324: }

3326: /*@
3327:    SNESGetGridSequence - gets the number of steps of grid sequencing that SNES does

3329:    Logically Collective on SNES

3331:    Input Parameter:
3332: .  snes - the SNES context

3334:    Output Parameter:
3335: .  steps - the number of refinements to do, defaults to 0

3337:    Options Database Keys:
3338: .    -snes_grid_sequence <steps>

3340:    Level: intermediate

3342:    Notes:
3343:    Use SNESGetSolution() to extract the fine grid solution after grid sequencing.

3345: .seealso: SNESSetTrustRegionTolerance(), SNESGetLagPreconditioner(), SNESSetLagJacobian(), SNESGetLagJacobian(), SNESSetGridSequence()

3347: @*/
3348: PetscErrorCode  SNESGetGridSequence(SNES snes,PetscInt *steps)
3349: {
3352:   *steps = snes->gridsequence;
3353:   return(0);
3354: }

3356: /*@
3357:    SNESGetLagPreconditioner - Indicates how often the preconditioner is rebuilt

3359:    Not Collective

3361:    Input Parameter:
3362: .  snes - the SNES context

3364:    Output Parameter:
3365: .   lag - -1 indicates NEVER rebuild, 1 means rebuild every time the Jacobian is computed within a single nonlinear solve, 2 means every second time
3366:          the Jacobian is built etc. -2 indicates rebuild preconditioner at next chance but then never rebuild after that

3368:    Options Database Keys:
3369: .    -snes_lag_preconditioner <lag>

3371:    Notes:
3372:    The default is 1
3373:    The preconditioner is ALWAYS built in the first iteration of a nonlinear solve unless lag is -1

3375:    Level: intermediate

3377: .seealso: SNESSetTrustRegionTolerance(), SNESSetLagPreconditioner()

3379: @*/
3380: PetscErrorCode  SNESGetLagPreconditioner(SNES snes,PetscInt *lag)
3381: {
3384:   *lag = snes->lagpreconditioner;
3385:   return(0);
3386: }

3388: /*@
3389:    SNESSetLagJacobian - Determines when the Jacobian is rebuilt in the nonlinear solve. See SNESSetLagPreconditioner() for determining how
3390:      often the preconditioner is rebuilt.

3392:    Logically Collective on SNES

3394:    Input Parameters:
3395: +  snes - the SNES context
3396: -  lag - -1 indicates NEVER rebuild, 1 means rebuild every time the Jacobian is computed within a single nonlinear solve, 2 means every second time
3397:          the Jacobian is built etc. -2 means rebuild at next chance but then never again

3399:    Options Database Keys:
3400: .    -snes_lag_jacobian <lag>

3402:    Notes:
3403:    The default is 1
3404:    The Jacobian is ALWAYS built in the first iteration of a nonlinear solve unless lag is -1
3405:    If  -1 is used before the very first nonlinear solve the CODE WILL FAIL! because no Jacobian is used, use -2 to indicate you want it recomputed
3406:    at the next Newton step but never again (unless it is reset to another value)

3408:    Level: intermediate

3410: .seealso: SNESSetTrustRegionTolerance(), SNESGetLagPreconditioner(), SNESSetLagPreconditioner(), SNESGetLagJacobian()

3412: @*/
3413: PetscErrorCode  SNESSetLagJacobian(SNES snes,PetscInt lag)
3414: {
3417:   if (lag < -2) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"Lag must be -2, -1, 1 or greater");
3418:   if (!lag) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"Lag cannot be 0");
3420:   snes->lagjacobian = lag;
3421:   return(0);
3422: }

3424: /*@
3425:    SNESGetLagJacobian - Indicates how often the Jacobian is rebuilt. See SNESGetLagPreconditioner() to determine when the preconditioner is rebuilt

3427:    Not Collective

3429:    Input Parameter:
3430: .  snes - the SNES context

3432:    Output Parameter:
3433: .   lag - -1 indicates NEVER rebuild, 1 means rebuild every time the Jacobian is computed within a single nonlinear solve, 2 means every second time
3434:          the Jacobian is built etc.

3436:    Options Database Keys:
3437: .    -snes_lag_jacobian <lag>

3439:    Notes:
3440:    The default is 1
3441:    The jacobian is ALWAYS built in the first iteration of a nonlinear solve unless lag is -1

3443:    Level: intermediate

3445: .seealso: SNESSetTrustRegionTolerance(), SNESSetLagJacobian(), SNESSetLagPreconditioner(), SNESGetLagPreconditioner()

3447: @*/
3448: PetscErrorCode  SNESGetLagJacobian(SNES snes,PetscInt *lag)
3449: {
3452:   *lag = snes->lagjacobian;
3453:   return(0);
3454: }

3456: /*@
3457:    SNESSetLagJacobianPersists - Set whether or not the Jacobian lagging persists through multiple solves

3459:    Logically collective on SNES

3461:    Input Parameter:
3462: +  snes - the SNES context
3463: -   flg - jacobian lagging persists if true

3465:    Options Database Keys:
3466: .    -snes_lag_jacobian_persists <flg>

3468:    Notes:
3469:     This is useful both for nonlinear preconditioning, where it's appropriate to have the Jacobian be stale by
3470:    several solves, and for implicit time-stepping, where Jacobian lagging in the inner nonlinear solve over several
3471:    timesteps may present huge efficiency gains.

3473:    Level: developer

3475: .seealso: SNESSetLagPreconditionerPersists(), SNESSetLagJacobian(), SNESGetLagJacobian(), SNESGetNPC()

3477: @*/
3478: PetscErrorCode  SNESSetLagJacobianPersists(SNES snes,PetscBool flg)
3479: {
3483:   snes->lagjac_persist = flg;
3484:   return(0);
3485: }

3487: /*@
3488:    SNESSetLagPreconditionerPersists - Set whether or not the preconditioner lagging persists through multiple solves

3490:    Logically Collective on SNES

3492:    Input Parameter:
3493: +  snes - the SNES context
3494: -   flg - preconditioner lagging persists if true

3496:    Options Database Keys:
3497: .    -snes_lag_jacobian_persists <flg>

3499:    Notes:
3500:     This is useful both for nonlinear preconditioning, where it's appropriate to have the preconditioner be stale
3501:    by several solves, and for implicit time-stepping, where preconditioner lagging in the inner nonlinear solve over
3502:    several timesteps may present huge efficiency gains.

3504:    Level: developer

3506: .seealso: SNESSetLagJacobianPersists(), SNESSetLagJacobian(), SNESGetLagJacobian(), SNESGetNPC()

3508: @*/
3509: PetscErrorCode  SNESSetLagPreconditionerPersists(SNES snes,PetscBool flg)
3510: {
3514:   snes->lagpre_persist = flg;
3515:   return(0);
3516: }

3518: /*@
3519:    SNESSetForceIteration - force SNESSolve() to take at least one iteration regardless of the initial residual norm

3521:    Logically Collective on SNES

3523:    Input Parameters:
3524: +  snes - the SNES context
3525: -  force - PETSC_TRUE require at least one iteration

3527:    Options Database Keys:
3528: .    -snes_force_iteration <force> - Sets forcing an iteration

3530:    Notes:
3531:    This is used sometimes with TS to prevent TS from detecting a false steady state solution

3533:    Level: intermediate

3535: .seealso: SNESSetTrustRegionTolerance(), SNESSetDivergenceTolerance()
3536: @*/
3537: PetscErrorCode  SNESSetForceIteration(SNES snes,PetscBool force)
3538: {
3541:   snes->forceiteration = force;
3542:   return(0);
3543: }

3545: /*@
3546:    SNESGetForceIteration - Whether or not to force SNESSolve() take at least one iteration regardless of the initial residual norm

3548:    Logically Collective on SNES

3550:    Input Parameters:
3551: .  snes - the SNES context

3553:    Output Parameter:
3554: .  force - PETSC_TRUE requires at least one iteration.

3556:    Level: intermediate

3558: .seealso: SNESSetForceIteration(), SNESSetTrustRegionTolerance(), SNESSetDivergenceTolerance()
3559: @*/
3560: PetscErrorCode  SNESGetForceIteration(SNES snes,PetscBool *force)
3561: {
3564:   *force = snes->forceiteration;
3565:   return(0);
3566: }

3568: /*@
3569:    SNESSetTolerances - Sets various parameters used in convergence tests.

3571:    Logically Collective on SNES

3573:    Input Parameters:
3574: +  snes - the SNES context
3575: .  abstol - absolute convergence tolerance
3576: .  rtol - relative convergence tolerance
3577: .  stol -  convergence tolerance in terms of the norm of the change in the solution between steps,  || delta x || < stol*|| x ||
3578: .  maxit - maximum number of iterations
3579: -  maxf - maximum number of function evaluations (-1 indicates no limit)

3581:    Options Database Keys:
3582: +    -snes_atol <abstol> - Sets abstol
3583: .    -snes_rtol <rtol> - Sets rtol
3584: .    -snes_stol <stol> - Sets stol
3585: .    -snes_max_it <maxit> - Sets maxit
3586: -    -snes_max_funcs <maxf> - Sets maxf

3588:    Notes:
3589:    The default maximum number of iterations is 50.
3590:    The default maximum number of function evaluations is 1000.

3592:    Level: intermediate

3594: .seealso: SNESSetTrustRegionTolerance(), SNESSetDivergenceTolerance(), SNESSetForceIteration()
3595: @*/
3596: PetscErrorCode  SNESSetTolerances(SNES snes,PetscReal abstol,PetscReal rtol,PetscReal stol,PetscInt maxit,PetscInt maxf)
3597: {

3606:   if (abstol != PETSC_DEFAULT) {
3607:     if (abstol < 0.0) SETERRQ1(PetscObjectComm((PetscObject)snes),PETSC_ERR_ARG_OUTOFRANGE,"Absolute tolerance %g must be non-negative",(double)abstol);
3608:     snes->abstol = abstol;
3609:   }
3610:   if (rtol != PETSC_DEFAULT) {
3611:     if (rtol < 0.0 || 1.0 <= rtol) SETERRQ1(PetscObjectComm((PetscObject)snes),PETSC_ERR_ARG_OUTOFRANGE,"Relative tolerance %g must be non-negative and less than 1.0",(double)rtol);
3612:     snes->rtol = rtol;
3613:   }
3614:   if (stol != PETSC_DEFAULT) {
3615:     if (stol < 0.0) SETERRQ1(PetscObjectComm((PetscObject)snes),PETSC_ERR_ARG_OUTOFRANGE,"Step tolerance %g must be non-negative",(double)stol);
3616:     snes->stol = stol;
3617:   }
3618:   if (maxit != PETSC_DEFAULT) {
3619:     if (maxit < 0) SETERRQ1(PetscObjectComm((PetscObject)snes),PETSC_ERR_ARG_OUTOFRANGE,"Maximum number of iterations %D must be non-negative",maxit);
3620:     snes->max_its = maxit;
3621:   }
3622:   if (maxf != PETSC_DEFAULT) {
3623:     if (maxf < -1) SETERRQ1(PetscObjectComm((PetscObject)snes),PETSC_ERR_ARG_OUTOFRANGE,"Maximum number of function evaluations %D must be -1 or nonnegative",maxf);
3624:     snes->max_funcs = maxf;
3625:   }
3626:   snes->tolerancesset = PETSC_TRUE;
3627:   return(0);
3628: }

3630: /*@
3631:    SNESSetDivergenceTolerance - Sets the divergence tolerance used for the SNES divergence test.

3633:    Logically Collective on SNES

3635:    Input Parameters:
3636: +  snes - the SNES context
3637: -  divtol - the divergence tolerance. Use -1 to deactivate the test.

3639:    Options Database Keys:
3640: .    -snes_divergence_tolerance <divtol> - Sets divtol

3642:    Notes:
3643:    The default divergence tolerance is 1e4.

3645:    Level: intermediate

3647: .seealso: SNESSetTolerances(), SNESGetDivergenceTolerance
3648: @*/
3649: PetscErrorCode  SNESSetDivergenceTolerance(SNES snes,PetscReal divtol)
3650: {

3655:   if (divtol != PETSC_DEFAULT) {
3656:     snes->divtol = divtol;
3657:   }
3658:   else {
3659:     snes->divtol = 1.0e4;
3660:   }
3661:   return(0);
3662: }

3664: /*@
3665:    SNESGetTolerances - Gets various parameters used in convergence tests.

3667:    Not Collective

3669:    Input Parameters:
3670: +  snes - the SNES context
3671: .  atol - absolute convergence tolerance
3672: .  rtol - relative convergence tolerance
3673: .  stol -  convergence tolerance in terms of the norm
3674:            of the change in the solution between steps
3675: .  maxit - maximum number of iterations
3676: -  maxf - maximum number of function evaluations

3678:    Notes:
3679:    The user can specify NULL for any parameter that is not needed.

3681:    Level: intermediate

3683: .seealso: SNESSetTolerances()
3684: @*/
3685: PetscErrorCode  SNESGetTolerances(SNES snes,PetscReal *atol,PetscReal *rtol,PetscReal *stol,PetscInt *maxit,PetscInt *maxf)
3686: {
3689:   if (atol)  *atol  = snes->abstol;
3690:   if (rtol)  *rtol  = snes->rtol;
3691:   if (stol)  *stol  = snes->stol;
3692:   if (maxit) *maxit = snes->max_its;
3693:   if (maxf)  *maxf  = snes->max_funcs;
3694:   return(0);
3695: }

3697: /*@
3698:    SNESGetDivergenceTolerance - Gets divergence tolerance used in divergence test.

3700:    Not Collective

3702:    Input Parameters:
3703: +  snes - the SNES context
3704: -  divtol - divergence tolerance

3706:    Level: intermediate

3708: .seealso: SNESSetDivergenceTolerance()
3709: @*/
3710: PetscErrorCode  SNESGetDivergenceTolerance(SNES snes,PetscReal *divtol)
3711: {
3714:   if (divtol) *divtol = snes->divtol;
3715:   return(0);
3716: }

3718: /*@
3719:    SNESSetTrustRegionTolerance - Sets the trust region parameter tolerance.

3721:    Logically Collective on SNES

3723:    Input Parameters:
3724: +  snes - the SNES context
3725: -  tol - tolerance

3727:    Options Database Key:
3728: .  -snes_trtol <tol> - Sets tol

3730:    Level: intermediate

3732: .seealso: SNESSetTolerances()
3733: @*/
3734: PetscErrorCode  SNESSetTrustRegionTolerance(SNES snes,PetscReal tol)
3735: {
3739:   snes->deltatol = tol;
3740:   return(0);
3741: }

3743: /*
3744:    Duplicate the lg monitors for SNES from KSP; for some reason with
3745:    dynamic libraries things don't work under Sun4 if we just use
3746:    macros instead of functions
3747: */
3748: PetscErrorCode  SNESMonitorLGResidualNorm(SNES snes,PetscInt it,PetscReal norm,void *ctx)
3749: {

3754:   KSPMonitorLGResidualNorm((KSP)snes,it,norm,ctx);
3755:   return(0);
3756: }

3758: PetscErrorCode  SNESMonitorLGCreate(MPI_Comm comm,const char host[],const char label[],int x,int y,int m,int n,PetscDrawLG *lgctx)
3759: {

3763:   KSPMonitorLGResidualNormCreate(comm,host,label,x,y,m,n,lgctx);
3764:   return(0);
3765: }

3767: PETSC_INTERN PetscErrorCode  SNESMonitorRange_Private(SNES,PetscInt,PetscReal*);

3769: PetscErrorCode  SNESMonitorLGRange(SNES snes,PetscInt n,PetscReal rnorm,void *monctx)
3770: {
3771:   PetscDrawLG      lg;
3772:   PetscErrorCode   ierr;
3773:   PetscReal        x,y,per;
3774:   PetscViewer      v = (PetscViewer)monctx;
3775:   static PetscReal prev; /* should be in the context */
3776:   PetscDraw        draw;

3780:   PetscViewerDrawGetDrawLG(v,0,&lg);
3781:   if (!n) {PetscDrawLGReset(lg);}
3782:   PetscDrawLGGetDraw(lg,&draw);
3783:   PetscDrawSetTitle(draw,"Residual norm");
3784:   x    = (PetscReal)n;
3785:   if (rnorm > 0.0) y = PetscLog10Real(rnorm);
3786:   else y = -15.0;
3787:   PetscDrawLGAddPoint(lg,&x,&y);
3788:   if (n < 20 || !(n % 5) || snes->reason) {
3789:     PetscDrawLGDraw(lg);
3790:     PetscDrawLGSave(lg);
3791:   }

3793:   PetscViewerDrawGetDrawLG(v,1,&lg);
3794:   if (!n) {PetscDrawLGReset(lg);}
3795:   PetscDrawLGGetDraw(lg,&draw);
3796:   PetscDrawSetTitle(draw,"% elemts > .2*max elemt");
3797:    SNESMonitorRange_Private(snes,n,&per);
3798:   x    = (PetscReal)n;
3799:   y    = 100.0*per;
3800:   PetscDrawLGAddPoint(lg,&x,&y);
3801:   if (n < 20 || !(n % 5) || snes->reason) {
3802:     PetscDrawLGDraw(lg);
3803:     PetscDrawLGSave(lg);
3804:   }

3806:   PetscViewerDrawGetDrawLG(v,2,&lg);
3807:   if (!n) {prev = rnorm;PetscDrawLGReset(lg);}
3808:   PetscDrawLGGetDraw(lg,&draw);
3809:   PetscDrawSetTitle(draw,"(norm -oldnorm)/oldnorm");
3810:   x    = (PetscReal)n;
3811:   y    = (prev - rnorm)/prev;
3812:   PetscDrawLGAddPoint(lg,&x,&y);
3813:   if (n < 20 || !(n % 5) || snes->reason) {
3814:     PetscDrawLGDraw(lg);
3815:     PetscDrawLGSave(lg);
3816:   }

3818:   PetscViewerDrawGetDrawLG(v,3,&lg);
3819:   if (!n) {PetscDrawLGReset(lg);}
3820:   PetscDrawLGGetDraw(lg,&draw);
3821:   PetscDrawSetTitle(draw,"(norm -oldnorm)/oldnorm*(% > .2 max)");
3822:   x    = (PetscReal)n;
3823:   y    = (prev - rnorm)/(prev*per);
3824:   if (n > 2) { /*skip initial crazy value */
3825:     PetscDrawLGAddPoint(lg,&x,&y);
3826:   }
3827:   if (n < 20 || !(n % 5) || snes->reason) {
3828:     PetscDrawLGDraw(lg);
3829:     PetscDrawLGSave(lg);
3830:   }
3831:   prev = rnorm;
3832:   return(0);
3833: }

3835: /*@
3836:    SNESMonitor - runs the user provided monitor routines, if they exist

3838:    Collective on SNES

3840:    Input Parameters:
3841: +  snes - nonlinear solver context obtained from SNESCreate()
3842: .  iter - iteration number
3843: -  rnorm - relative norm of the residual

3845:    Notes:
3846:    This routine is called by the SNES implementations.
3847:    It does not typically need to be called by the user.

3849:    Level: developer

3851: .seealso: SNESMonitorSet()
3852: @*/
3853: PetscErrorCode  SNESMonitor(SNES snes,PetscInt iter,PetscReal rnorm)
3854: {
3856:   PetscInt       i,n = snes->numbermonitors;

3859:   VecLockReadPush(snes->vec_sol);
3860:   for (i=0; i<n; i++) {
3861:     (*snes->monitor[i])(snes,iter,rnorm,snes->monitorcontext[i]);
3862:   }
3863:   VecLockReadPop(snes->vec_sol);
3864:   return(0);
3865: }

3867: /* ------------ Routines to set performance monitoring options ----------- */

3869: /*MC
3870:     SNESMonitorFunction - functional form passed to SNESMonitorSet() to monitor convergence of nonlinear solver

3872:      Synopsis:
3873:  #include <petscsnes.h>
3874: $    PetscErrorCode SNESMonitorFunction(SNES snes,PetscInt its, PetscReal norm,void *mctx)

3876:      Collective on snes

3878:     Input Parameters:
3879: +    snes - the SNES context
3880: .    its - iteration number
3881: .    norm - 2-norm function value (may be estimated)
3882: -    mctx - [optional] monitoring context

3884:    Level: advanced

3886: .seealso:   SNESMonitorSet(), SNESMonitorGet()
3887: M*/

3889: /*@C
3890:    SNESMonitorSet - Sets an ADDITIONAL function that is to be used at every
3891:    iteration of the nonlinear solver to display the iteration's
3892:    progress.

3894:    Logically Collective on SNES

3896:    Input Parameters:
3897: +  snes - the SNES context
3898: .  f - the monitor function, see SNESMonitorFunction for the calling sequence
3899: .  mctx - [optional] user-defined context for private data for the
3900:           monitor routine (use NULL if no context is desired)
3901: -  monitordestroy - [optional] routine that frees monitor context
3902:           (may be NULL)

3904:    Options Database Keys:
3905: +    -snes_monitor        - sets SNESMonitorDefault()
3906: .    -snes_monitor_lg_residualnorm    - sets line graph monitor,
3907:                             uses SNESMonitorLGCreate()
3908: -    -snes_monitor_cancel - cancels all monitors that have
3909:                             been hardwired into a code by
3910:                             calls to SNESMonitorSet(), but
3911:                             does not cancel those set via
3912:                             the options database.

3914:    Notes:
3915:    Several different monitoring routines may be set by calling
3916:    SNESMonitorSet() multiple times; all will be called in the
3917:    order in which they were set.

3919:    Fortran Notes:
3920:     Only a single monitor function can be set for each SNES object

3922:    Level: intermediate

3924: .seealso: SNESMonitorDefault(), SNESMonitorCancel(), SNESMonitorFunction
3925: @*/
3926: PetscErrorCode  SNESMonitorSet(SNES snes,PetscErrorCode (*f)(SNES,PetscInt,PetscReal,void*),void *mctx,PetscErrorCode (*monitordestroy)(void**))
3927: {
3928:   PetscInt       i;
3930:   PetscBool      identical;

3934:   for (i=0; i<snes->numbermonitors;i++) {
3935:     PetscMonitorCompare((PetscErrorCode (*)(void))f,mctx,monitordestroy,(PetscErrorCode (*)(void))snes->monitor[i],snes->monitorcontext[i],snes->monitordestroy[i],&identical);
3936:     if (identical) return(0);
3937:   }
3938:   if (snes->numbermonitors >= MAXSNESMONITORS) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"Too many monitors set");
3939:   snes->monitor[snes->numbermonitors]          = f;
3940:   snes->monitordestroy[snes->numbermonitors]   = monitordestroy;
3941:   snes->monitorcontext[snes->numbermonitors++] = (void*)mctx;
3942:   return(0);
3943: }

3945: /*@
3946:    SNESMonitorCancel - Clears all the monitor functions for a SNES object.

3948:    Logically Collective on SNES

3950:    Input Parameters:
3951: .  snes - the SNES context

3953:    Options Database Key:
3954: .  -snes_monitor_cancel - cancels all monitors that have been hardwired
3955:     into a code by calls to SNESMonitorSet(), but does not cancel those
3956:     set via the options database

3958:    Notes:
3959:    There is no way to clear one specific monitor from a SNES object.

3961:    Level: intermediate

3963: .seealso: SNESMonitorDefault(), SNESMonitorSet()
3964: @*/
3965: PetscErrorCode  SNESMonitorCancel(SNES snes)
3966: {
3968:   PetscInt       i;

3972:   for (i=0; i<snes->numbermonitors; i++) {
3973:     if (snes->monitordestroy[i]) {
3974:       (*snes->monitordestroy[i])(&snes->monitorcontext[i]);
3975:     }
3976:   }
3977:   snes->numbermonitors = 0;
3978:   return(0);
3979: }

3981: /*MC
3982:     SNESConvergenceTestFunction - functional form used for testing of convergence of nonlinear solver

3984:      Synopsis:
3985:  #include <petscsnes.h>
3986: $     PetscErrorCode SNESConvergenceTest(SNES snes,PetscInt it,PetscReal xnorm,PetscReal gnorm,PetscReal f,SNESConvergedReason *reason,void *cctx)

3988:      Collective on snes

3990:     Input Parameters:
3991: +    snes - the SNES context
3992: .    it - current iteration (0 is the first and is before any Newton step)
3993: .    xnorm - 2-norm of current iterate
3994: .    gnorm - 2-norm of current step
3995: .    f - 2-norm of function
3996: -    cctx - [optional] convergence context

3998:     Output Parameter:
3999: .    reason - reason for convergence/divergence, only needs to be set when convergence or divergence is detected

4001:    Level: intermediate

4003: .seealso:   SNESSetConvergenceTest(), SNESGetConvergenceTest()
4004: M*/

4006: /*@C
4007:    SNESSetConvergenceTest - Sets the function that is to be used
4008:    to test for convergence of the nonlinear iterative solution.

4010:    Logically Collective on SNES

4012:    Input Parameters:
4013: +  snes - the SNES context
4014: .  SNESConvergenceTestFunction - routine to test for convergence
4015: .  cctx - [optional] context for private data for the convergence routine  (may be NULL)
4016: -  destroy - [optional] destructor for the context (may be NULL; PETSC_NULL_FUNCTION in Fortran)

4018:    Level: advanced

4020: .seealso: SNESConvergedDefault(), SNESConvergedSkip(), SNESConvergenceTestFunction
4021: @*/
4022: PetscErrorCode  SNESSetConvergenceTest(SNES snes,PetscErrorCode (*SNESConvergenceTestFunction)(SNES,PetscInt,PetscReal,PetscReal,PetscReal,SNESConvergedReason*,void*),void *cctx,PetscErrorCode (*destroy)(void*))
4023: {

4028:   if (!SNESConvergenceTestFunction) SNESConvergenceTestFunction = SNESConvergedSkip;
4029:   if (snes->ops->convergeddestroy) {
4030:     (*snes->ops->convergeddestroy)(snes->cnvP);
4031:   }
4032:   snes->ops->converged        = SNESConvergenceTestFunction;
4033:   snes->ops->convergeddestroy = destroy;
4034:   snes->cnvP                  = cctx;
4035:   return(0);
4036: }

4038: /*@
4039:    SNESGetConvergedReason - Gets the reason the SNES iteration was stopped.

4041:    Not Collective

4043:    Input Parameter:
4044: .  snes - the SNES context

4046:    Output Parameter:
4047: .  reason - negative value indicates diverged, positive value converged, see SNESConvergedReason or the
4048:             manual pages for the individual convergence tests for complete lists

4050:    Options Database:
4051: .   -snes_converged_reason - prints the reason to standard out

4053:    Level: intermediate

4055:    Notes:
4056:     Should only be called after the call the SNESSolve() is complete, if it is called earlier it returns the value SNES__CONVERGED_ITERATING.

4058: .seealso: SNESSetConvergenceTest(), SNESSetConvergedReason(), SNESConvergedReason
4059: @*/
4060: PetscErrorCode SNESGetConvergedReason(SNES snes,SNESConvergedReason *reason)
4061: {
4065:   *reason = snes->reason;
4066:   return(0);
4067: }

4069: /*@
4070:    SNESSetConvergedReason - Sets the reason the SNES iteration was stopped.

4072:    Not Collective

4074:    Input Parameters:
4075: +  snes - the SNES context
4076: -  reason - negative value indicates diverged, positive value converged, see SNESConvergedReason or the
4077:             manual pages for the individual convergence tests for complete lists

4079:    Level: intermediate

4081: .seealso: SNESGetConvergedReason(), SNESSetConvergenceTest(), SNESConvergedReason
4082: @*/
4083: PetscErrorCode SNESSetConvergedReason(SNES snes,SNESConvergedReason reason)
4084: {
4087:   snes->reason = reason;
4088:   return(0);
4089: }

4091: /*@
4092:    SNESSetConvergenceHistory - Sets the array used to hold the convergence history.

4094:    Logically Collective on SNES

4096:    Input Parameters:
4097: +  snes - iterative context obtained from SNESCreate()
4098: .  a   - array to hold history, this array will contain the function norms computed at each step
4099: .  its - integer array holds the number of linear iterations for each solve.
4100: .  na  - size of a and its
4101: -  reset - PETSC_TRUE indicates each new nonlinear solve resets the history counter to zero,
4102:            else it continues storing new values for new nonlinear solves after the old ones

4104:    Notes:
4105:    If 'a' and 'its' are NULL then space is allocated for the history. If 'na' PETSC_DECIDE or PETSC_DEFAULT then a
4106:    default array of length 10000 is allocated.

4108:    This routine is useful, e.g., when running a code for purposes
4109:    of accurate performance monitoring, when no I/O should be done
4110:    during the section of code that is being timed.

4112:    Level: intermediate

4114: .seealso: SNESGetConvergenceHistory()

4116: @*/
4117: PetscErrorCode  SNESSetConvergenceHistory(SNES snes,PetscReal a[],PetscInt its[],PetscInt na,PetscBool reset)
4118: {

4125:   if (!a) {
4126:     if (na == PETSC_DECIDE || na == PETSC_DEFAULT) na = 1000;
4127:     PetscCalloc2(na,&a,na,&its);
4128:     snes->conv_hist_alloc = PETSC_TRUE;
4129:   }
4130:   snes->conv_hist       = a;
4131:   snes->conv_hist_its   = its;
4132:   snes->conv_hist_max   = na;
4133:   snes->conv_hist_len   = 0;
4134:   snes->conv_hist_reset = reset;
4135:   return(0);
4136: }

4138: #if defined(PETSC_HAVE_MATLAB_ENGINE)
4139: #include <engine.h>   /* MATLAB include file */
4140: #include <mex.h>      /* MATLAB include file */

4142: PETSC_EXTERN mxArray *SNESGetConvergenceHistoryMatlab(SNES snes)
4143: {
4144:   mxArray   *mat;
4145:   PetscInt  i;
4146:   PetscReal *ar;

4149:   mat = mxCreateDoubleMatrix(snes->conv_hist_len,1,mxREAL);
4150:   ar  = (PetscReal*) mxGetData(mat);
4151:   for (i=0; i<snes->conv_hist_len; i++) ar[i] = snes->conv_hist[i];
4152:   PetscFunctionReturn(mat);
4153: }
4154: #endif

4156: /*@C
4157:    SNESGetConvergenceHistory - Gets the array used to hold the convergence history.

4159:    Not Collective

4161:    Input Parameter:
4162: .  snes - iterative context obtained from SNESCreate()

4164:    Output Parameters:
4165: +  a   - array to hold history
4166: .  its - integer array holds the number of linear iterations (or
4167:          negative if not converged) for each solve.
4168: -  na  - size of a and its

4170:    Notes:
4171:     The calling sequence for this routine in Fortran is
4172: $   call SNESGetConvergenceHistory(SNES snes, integer na, integer ierr)

4174:    This routine is useful, e.g., when running a code for purposes
4175:    of accurate performance monitoring, when no I/O should be done
4176:    during the section of code that is being timed.

4178:    Level: intermediate

4180: .seealso: SNESSetConvergenceHistory()

4182: @*/
4183: PetscErrorCode  SNESGetConvergenceHistory(SNES snes,PetscReal *a[],PetscInt *its[],PetscInt *na)
4184: {
4187:   if (a)   *a   = snes->conv_hist;
4188:   if (its) *its = snes->conv_hist_its;
4189:   if (na)  *na  = snes->conv_hist_len;
4190:   return(0);
4191: }

4193: /*@C
4194:   SNESSetUpdate - Sets the general-purpose update function called
4195:   at the beginning of every iteration of the nonlinear solve. Specifically
4196:   it is called just before the Jacobian is "evaluated".

4198:   Logically Collective on SNES

4200:   Input Parameters:
4201: + snes - The nonlinear solver context
4202: - func - The function

4204:   Calling sequence of func:
4205: $ func (SNES snes, PetscInt step);

4207: . step - The current step of the iteration

4209:   Level: advanced

4211:   Note: This is NOT what one uses to update the ghost points before a function evaluation, that should be done at the beginning of your FormFunction()
4212:         This is not used by most users.

4214: .seealso SNESSetJacobian(), SNESSolve()
4215: @*/
4216: PetscErrorCode  SNESSetUpdate(SNES snes, PetscErrorCode (*func)(SNES, PetscInt))
4217: {
4220:   snes->ops->update = func;
4221:   return(0);
4222: }

4224: /*
4225:    SNESScaleStep_Private - Scales a step so that its length is less than the
4226:    positive parameter delta.

4228:     Input Parameters:
4229: +   snes - the SNES context
4230: .   y - approximate solution of linear system
4231: .   fnorm - 2-norm of current function
4232: -   delta - trust region size

4234:     Output Parameters:
4235: +   gpnorm - predicted function norm at the new point, assuming local
4236:     linearization.  The value is zero if the step lies within the trust
4237:     region, and exceeds zero otherwise.
4238: -   ynorm - 2-norm of the step

4240:     Note:
4241:     For non-trust region methods such as SNESNEWTONLS, the parameter delta
4242:     is set to be the maximum allowable step size.

4244: */
4245: PetscErrorCode SNESScaleStep_Private(SNES snes,Vec y,PetscReal *fnorm,PetscReal *delta,PetscReal *gpnorm,PetscReal *ynorm)
4246: {
4247:   PetscReal      nrm;
4248:   PetscScalar    cnorm;


4256:   VecNorm(y,NORM_2,&nrm);
4257:   if (nrm > *delta) {
4258:     nrm     = *delta/nrm;
4259:     *gpnorm = (1.0 - nrm)*(*fnorm);
4260:     cnorm   = nrm;
4261:     VecScale(y,cnorm);
4262:     *ynorm  = *delta;
4263:   } else {
4264:     *gpnorm = 0.0;
4265:     *ynorm  = nrm;
4266:   }
4267:   return(0);
4268: }

4270: /*@
4271:    SNESReasonView - Displays the reason a SNES solve converged or diverged to a viewer

4273:    Collective on SNES

4275:    Parameter:
4276: +  snes - iterative context obtained from SNESCreate()
4277: -  viewer - the viewer to display the reason


4280:    Options Database Keys:
4281: .  -snes_converged_reason - print reason for converged or diverged, also prints number of iterations
4282: .  -snes_converged_reason ::failed - only print reason and number of iterations when diverged


4285:    Level: beginner

4287: .seealso: SNESCreate(), SNESSetUp(), SNESDestroy(), SNESSetTolerances(), SNESConvergedDefault()

4289: @*/
4290: PetscErrorCode  SNESReasonView(SNES snes,PetscViewer viewer)
4291: {
4292:   PetscViewerFormat format;
4293:   PetscBool         isAscii;
4294:   PetscErrorCode    ierr;

4297:   PetscObjectTypeCompare((PetscObject)viewer,PETSCVIEWERASCII,&isAscii);
4298:   if (isAscii) {
4299:     PetscViewerGetFormat(viewer, &format);
4300:     PetscViewerASCIIAddTab(viewer,((PetscObject)snes)->tablevel);
4301:     if (format == PETSC_VIEWER_ASCII_INFO_DETAIL) {
4302:       DM                dm;
4303:       Vec               u;
4304:       PetscDS           prob;
4305:       PetscInt          Nf, f;
4306:       PetscErrorCode (**exactSol)(PetscInt, PetscReal, const PetscReal[], PetscInt, PetscScalar[], void *);
4307:       void            **exactCtx;
4308:       PetscReal         error;

4310:       SNESGetDM(snes, &dm);
4311:       SNESGetSolution(snes, &u);
4312:       DMGetDS(dm, &prob);
4313:       PetscDSGetNumFields(prob, &Nf);
4314:       PetscMalloc2(Nf, &exactSol, Nf, &exactCtx);
4315:       for (f = 0; f < Nf; ++f) {PetscDSGetExactSolution(prob, f, &exactSol[f], &exactCtx[f]);}
4316:       DMComputeL2Diff(dm, 0.0, exactSol, exactCtx, u, &error);
4317:       PetscFree2(exactSol, exactCtx);
4318:       if (error < 1.0e-11) {PetscViewerASCIIPrintf(viewer, "L_2 Error: < 1.0e-11\n");}
4319:       else                 {PetscViewerASCIIPrintf(viewer, "L_2 Error: %g\n", error);}
4320:     }
4321:     if (snes->reason > 0 && format != PETSC_VIEWER_FAILED) {
4322:       if (((PetscObject) snes)->prefix) {
4323:         PetscViewerASCIIPrintf(viewer,"Nonlinear %s solve converged due to %s iterations %D\n",((PetscObject) snes)->prefix,SNESConvergedReasons[snes->reason],snes->iter);
4324:       } else {
4325:         PetscViewerASCIIPrintf(viewer,"Nonlinear solve converged due to %s iterations %D\n",SNESConvergedReasons[snes->reason],snes->iter);
4326:       }
4327:     } else if (snes->reason <= 0) {
4328:       if (((PetscObject) snes)->prefix) {
4329:         PetscViewerASCIIPrintf(viewer,"Nonlinear %s solve did not converge due to %s iterations %D\n",((PetscObject) snes)->prefix,SNESConvergedReasons[snes->reason],snes->iter);
4330:       } else {
4331:         PetscViewerASCIIPrintf(viewer,"Nonlinear solve did not converge due to %s iterations %D\n",SNESConvergedReasons[snes->reason],snes->iter);
4332:       }
4333:     }
4334:     PetscViewerASCIISubtractTab(viewer,((PetscObject)snes)->tablevel);
4335:   }
4336:   return(0);
4337: }

4339: /*@C
4340:   SNESReasonViewFromOptions - Processes command line options to determine if/how a SNESReason is to be viewed.

4342:   Collective on SNES

4344:   Input Parameters:
4345: . snes   - the SNES object

4347:   Level: intermediate

4349: @*/
4350: PetscErrorCode SNESReasonViewFromOptions(SNES snes)
4351: {
4352:   PetscErrorCode    ierr;
4353:   PetscViewer       viewer;
4354:   PetscBool         flg;
4355:   static PetscBool  incall = PETSC_FALSE;
4356:   PetscViewerFormat format;

4359:   if (incall) return(0);
4360:   incall = PETSC_TRUE;
4361:   PetscOptionsGetViewer(PetscObjectComm((PetscObject)snes),((PetscObject)snes)->options,((PetscObject)snes)->prefix,"-snes_converged_reason",&viewer,&format,&flg);
4362:   if (flg) {
4363:     PetscViewerPushFormat(viewer,format);
4364:     SNESReasonView(snes,viewer);
4365:     PetscViewerPopFormat(viewer);
4366:     PetscViewerDestroy(&viewer);
4367:   }
4368:   incall = PETSC_FALSE;
4369:   return(0);
4370: }

4372: /*@
4373:    SNESSolve - Solves a nonlinear system F(x) = b.
4374:    Call SNESSolve() after calling SNESCreate() and optional routines of the form SNESSetXXX().

4376:    Collective on SNES

4378:    Input Parameters:
4379: +  snes - the SNES context
4380: .  b - the constant part of the equation F(x) = b, or NULL to use zero.
4381: -  x - the solution vector.

4383:    Notes:
4384:    The user should initialize the vector,x, with the initial guess
4385:    for the nonlinear solve prior to calling SNESSolve.  In particular,
4386:    to employ an initial guess of zero, the user should explicitly set
4387:    this vector to zero by calling VecSet().

4389:    Level: beginner

4391: .seealso: SNESCreate(), SNESDestroy(), SNESSetFunction(), SNESSetJacobian(), SNESSetGridSequence(), SNESGetSolution()
4392: @*/
4393: PetscErrorCode  SNESSolve(SNES snes,Vec b,Vec x)
4394: {
4395:   PetscErrorCode    ierr;
4396:   PetscBool         flg;
4397:   PetscInt          grid;
4398:   Vec               xcreated = NULL;
4399:   DM                dm;


4408:   /* High level operations using the nonlinear solver */
4409:   {
4410:     PetscViewer       viewer;
4411:     PetscViewerFormat format;
4412:     PetscInt          num;
4413:     PetscBool         flg;
4414:     static PetscBool  incall = PETSC_FALSE;

4416:     if (!incall) {
4417:       /* Estimate the convergence rate of the discretization */
4418:       PetscOptionsGetViewer(PetscObjectComm((PetscObject) snes),((PetscObject)snes)->options, ((PetscObject) snes)->prefix, "-snes_convergence_estimate", &viewer, &format, &flg);
4419:       if (flg) {
4420:         PetscConvEst conv;
4421:         DM           dm;
4422:         PetscReal   *alpha; /* Convergence rate of the solution error for each field in the L_2 norm */
4423:         PetscInt     Nf;

4425:         incall = PETSC_TRUE;
4426:         SNESGetDM(snes, &dm);
4427:         DMGetNumFields(dm, &Nf);
4428:         PetscCalloc1(Nf, &alpha);
4429:         PetscConvEstCreate(PetscObjectComm((PetscObject) snes), &conv);
4430:         PetscConvEstSetSolver(conv, (PetscObject) snes);
4431:         PetscConvEstSetFromOptions(conv);
4432:         PetscConvEstSetUp(conv);
4433:         PetscConvEstGetConvRate(conv, alpha);
4434:         PetscViewerPushFormat(viewer, format);
4435:         PetscConvEstRateView(conv, alpha, viewer);
4436:         PetscViewerPopFormat(viewer);
4437:         PetscViewerDestroy(&viewer);
4438:         PetscConvEstDestroy(&conv);
4439:         PetscFree(alpha);
4440:         incall = PETSC_FALSE;
4441:       }
4442:       /* Adaptively refine the initial grid */
4443:       num  = 1;
4444:       PetscOptionsGetInt(NULL, ((PetscObject) snes)->prefix, "-snes_adapt_initial", &num, &flg);
4445:       if (flg) {
4446:         DMAdaptor adaptor;

4448:         incall = PETSC_TRUE;
4449:         DMAdaptorCreate(PetscObjectComm((PetscObject)snes), &adaptor);
4450:         DMAdaptorSetSolver(adaptor, snes);
4451:         DMAdaptorSetSequenceLength(adaptor, num);
4452:         DMAdaptorSetFromOptions(adaptor);
4453:         DMAdaptorSetUp(adaptor);
4454:         DMAdaptorAdapt(adaptor, x, DM_ADAPTATION_INITIAL, &dm, &x);
4455:         DMAdaptorDestroy(&adaptor);
4456:         incall = PETSC_FALSE;
4457:       }
4458:       /* Use grid sequencing to adapt */
4459:       num  = 0;
4460:       PetscOptionsGetInt(NULL, ((PetscObject) snes)->prefix, "-snes_adapt_sequence", &num, NULL);
4461:       if (num) {
4462:         DMAdaptor adaptor;

4464:         incall = PETSC_TRUE;
4465:         DMAdaptorCreate(PetscObjectComm((PetscObject)snes), &adaptor);
4466:         DMAdaptorSetSolver(adaptor, snes);
4467:         DMAdaptorSetSequenceLength(adaptor, num);
4468:         DMAdaptorSetFromOptions(adaptor);
4469:         DMAdaptorSetUp(adaptor);
4470:         DMAdaptorAdapt(adaptor, x, DM_ADAPTATION_SEQUENTIAL, &dm, &x);
4471:         DMAdaptorDestroy(&adaptor);
4472:         incall = PETSC_FALSE;
4473:       }
4474:     }
4475:   }
4476:   if (!x) {
4477:     SNESGetDM(snes,&dm);
4478:     DMCreateGlobalVector(dm,&xcreated);
4479:     x    = xcreated;
4480:   }
4481:   SNESViewFromOptions(snes,NULL,"-snes_view_pre");

4483:   for (grid=0; grid<snes->gridsequence; grid++) {PetscViewerASCIIPushTab(PETSC_VIEWER_STDOUT_(PetscObjectComm((PetscObject)snes)));}
4484:   for (grid=0; grid<snes->gridsequence+1; grid++) {

4486:     /* set solution vector */
4487:     if (!grid) {PetscObjectReference((PetscObject)x);}
4488:     VecDestroy(&snes->vec_sol);
4489:     snes->vec_sol = x;
4490:     SNESGetDM(snes,&dm);

4492:     /* set affine vector if provided */
4493:     if (b) { PetscObjectReference((PetscObject)b); }
4494:     VecDestroy(&snes->vec_rhs);
4495:     snes->vec_rhs = b;

4497:     if (snes->vec_rhs && (snes->vec_func == snes->vec_rhs)) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_IDN,"Right hand side vector cannot be function vector");
4498:     if (snes->vec_func == snes->vec_sol) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_IDN,"Solution vector cannot be function vector");
4499:     if (snes->vec_rhs  == snes->vec_sol) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_IDN,"Solution vector cannot be right hand side vector");
4500:     if (!snes->vec_sol_update /* && snes->vec_sol */) {
4501:       VecDuplicate(snes->vec_sol,&snes->vec_sol_update);
4502:       PetscLogObjectParent((PetscObject)snes,(PetscObject)snes->vec_sol_update);
4503:     }
4504:     DMShellSetGlobalVector(dm,snes->vec_sol);
4505:     SNESSetUp(snes);

4507:     if (!grid) {
4508:       if (snes->ops->computeinitialguess) {
4509:         (*snes->ops->computeinitialguess)(snes,snes->vec_sol,snes->initialguessP);
4510:       }
4511:     }

4513:     if (snes->conv_hist_reset) snes->conv_hist_len = 0;
4514:     if (snes->counters_reset) {snes->nfuncs = 0; snes->linear_its = 0; snes->numFailures = 0;}

4516:     PetscLogEventBegin(SNES_Solve,snes,0,0,0);
4517:     (*snes->ops->solve)(snes);
4518:     PetscLogEventEnd(SNES_Solve,snes,0,0,0);
4519:     if (!snes->reason) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_PLIB,"Internal error, solver returned without setting converged reason");
4520:     snes->domainerror = PETSC_FALSE; /* clear the flag if it has been set */

4522:     if (snes->lagjac_persist) snes->jac_iter += snes->iter;
4523:     if (snes->lagpre_persist) snes->pre_iter += snes->iter;

4525:     PetscOptionsGetViewer(PetscObjectComm((PetscObject)snes),((PetscObject)snes)->options,((PetscObject)snes)->prefix,"-snes_test_local_min",NULL,NULL,&flg);
4526:     if (flg && !PetscPreLoadingOn) { SNESTestLocalMin(snes); }
4527:     SNESReasonViewFromOptions(snes);

4529:     if (snes->errorifnotconverged && snes->reason < 0) SETERRQ(PetscObjectComm((PetscObject)snes),PETSC_ERR_NOT_CONVERGED,"SNESSolve has not converged");
4530:     if (snes->reason < 0) break;
4531:     if (grid <  snes->gridsequence) {
4532:       DM  fine;
4533:       Vec xnew;
4534:       Mat interp;

4536:       DMRefine(snes->dm,PetscObjectComm((PetscObject)snes),&fine);
4537:       if (!fine) SETERRQ(PetscObjectComm((PetscObject)snes),PETSC_ERR_ARG_INCOMP,"DMRefine() did not perform any refinement, cannot continue grid sequencing");
4538:       DMCreateInterpolation(snes->dm,fine,&interp,NULL);
4539:       DMCreateGlobalVector(fine,&xnew);
4540:       MatInterpolate(interp,x,xnew);
4541:       DMInterpolate(snes->dm,interp,fine);
4542:       MatDestroy(&interp);
4543:       x    = xnew;

4545:       SNESReset(snes);
4546:       SNESSetDM(snes,fine);
4547:       SNESResetFromOptions(snes);
4548:       DMDestroy(&fine);
4549:       PetscViewerASCIIPopTab(PETSC_VIEWER_STDOUT_(PetscObjectComm((PetscObject)snes)));
4550:     }
4551:   }
4552:   SNESViewFromOptions(snes,NULL,"-snes_view");
4553:   VecViewFromOptions(snes->vec_sol,(PetscObject)snes,"-snes_view_solution");
4554:   DMMonitor(snes->dm);

4556:   VecDestroy(&xcreated);
4557:   PetscObjectSAWsBlock((PetscObject)snes);
4558:   return(0);
4559: }

4561: /* --------- Internal routines for SNES Package --------- */

4563: /*@C
4564:    SNESSetType - Sets the method for the nonlinear solver.

4566:    Collective on SNES

4568:    Input Parameters:
4569: +  snes - the SNES context
4570: -  type - a known method

4572:    Options Database Key:
4573: .  -snes_type <type> - Sets the method; use -help for a list
4574:    of available methods (for instance, newtonls or newtontr)

4576:    Notes:
4577:    See "petsc/include/petscsnes.h" for available methods (for instance)
4578: +    SNESNEWTONLS - Newton's method with line search
4579:      (systems of nonlinear equations)
4580: -    SNESNEWTONTR - Newton's method with trust region
4581:      (systems of nonlinear equations)

4583:   Normally, it is best to use the SNESSetFromOptions() command and then
4584:   set the SNES solver type from the options database rather than by using
4585:   this routine.  Using the options database provides the user with
4586:   maximum flexibility in evaluating the many nonlinear solvers.
4587:   The SNESSetType() routine is provided for those situations where it
4588:   is necessary to set the nonlinear solver independently of the command
4589:   line or options database.  This might be the case, for example, when
4590:   the choice of solver changes during the execution of the program,
4591:   and the user's Section 1.5 Writing Application Codes with PETSc is taking responsibility for choosing the
4592:   appropriate method.

4594:     Developer Notes:
4595:     SNESRegister() adds a constructor for a new SNESType to SNESList, SNESSetType() locates
4596:     the constructor in that list and calls it to create the spexific object.

4598:   Level: intermediate

4600: .seealso: SNESType, SNESCreate(), SNESDestroy(), SNESGetType(), SNESSetFromOptions()

4602: @*/
4603: PetscErrorCode  SNESSetType(SNES snes,SNESType type)
4604: {
4605:   PetscErrorCode ierr,(*r)(SNES);
4606:   PetscBool      match;


4612:   PetscObjectTypeCompare((PetscObject)snes,type,&match);
4613:   if (match) return(0);

4615:   PetscFunctionListFind(SNESList,type,&r);
4616:   if (!r) SETERRQ1(PETSC_COMM_SELF,PETSC_ERR_ARG_UNKNOWN_TYPE,"Unable to find requested SNES type %s",type);
4617:   /* Destroy the previous private SNES context */
4618:   if (snes->ops->destroy) {
4619:     (*(snes)->ops->destroy)(snes);
4620:     snes->ops->destroy = NULL;
4621:   }
4622:   /* Reinitialize function pointers in SNESOps structure */
4623:   snes->ops->setup          = NULL;
4624:   snes->ops->solve          = NULL;
4625:   snes->ops->view           = NULL;
4626:   snes->ops->setfromoptions = NULL;
4627:   snes->ops->destroy        = NULL;

4629:   /* It may happen the user has customized the line search before calling SNESSetType */
4630:   if (((PetscObject)snes)->type_name) {
4631:     SNESLineSearchDestroy(&snes->linesearch);
4632:   }

4634:   /* Call the SNESCreate_XXX routine for this particular Nonlinear solver */
4635:   snes->setupcalled = PETSC_FALSE;

4637:   PetscObjectChangeTypeName((PetscObject)snes,type);
4638:   (*r)(snes);
4639:   return(0);
4640: }

4642: /*@C
4643:    SNESGetType - Gets the SNES method type and name (as a string).

4645:    Not Collective

4647:    Input Parameter:
4648: .  snes - nonlinear solver context

4650:    Output Parameter:
4651: .  type - SNES method (a character string)

4653:    Level: intermediate

4655: @*/
4656: PetscErrorCode  SNESGetType(SNES snes,SNESType *type)
4657: {
4661:   *type = ((PetscObject)snes)->type_name;
4662:   return(0);
4663: }

4665: /*@
4666:   SNESSetSolution - Sets the solution vector for use by the SNES routines.

4668:   Logically Collective on SNES

4670:   Input Parameters:
4671: + snes - the SNES context obtained from SNESCreate()
4672: - u    - the solution vector

4674:   Level: beginner

4676: @*/
4677: PetscErrorCode SNESSetSolution(SNES snes, Vec u)
4678: {
4679:   DM             dm;

4685:   PetscObjectReference((PetscObject) u);
4686:   VecDestroy(&snes->vec_sol);

4688:   snes->vec_sol = u;

4690:   SNESGetDM(snes, &dm);
4691:   DMShellSetGlobalVector(dm, u);
4692:   return(0);
4693: }

4695: /*@
4696:    SNESGetSolution - Returns the vector where the approximate solution is
4697:    stored. This is the fine grid solution when using SNESSetGridSequence().

4699:    Not Collective, but Vec is parallel if SNES is parallel

4701:    Input Parameter:
4702: .  snes - the SNES context

4704:    Output Parameter:
4705: .  x - the solution

4707:    Level: intermediate

4709: .seealso:  SNESGetSolutionUpdate(), SNESGetFunction()
4710: @*/
4711: PetscErrorCode  SNESGetSolution(SNES snes,Vec *x)
4712: {
4716:   *x = snes->vec_sol;
4717:   return(0);
4718: }

4720: /*@
4721:    SNESGetSolutionUpdate - Returns the vector where the solution update is
4722:    stored.

4724:    Not Collective, but Vec is parallel if SNES is parallel

4726:    Input Parameter:
4727: .  snes - the SNES context

4729:    Output Parameter:
4730: .  x - the solution update

4732:    Level: advanced

4734: .seealso: SNESGetSolution(), SNESGetFunction()
4735: @*/
4736: PetscErrorCode  SNESGetSolutionUpdate(SNES snes,Vec *x)
4737: {
4741:   *x = snes->vec_sol_update;
4742:   return(0);
4743: }

4745: /*@C
4746:    SNESGetFunction - Returns the vector where the function is stored.

4748:    Not Collective, but Vec is parallel if SNES is parallel. Collective if Vec is requested, but has not been created yet.

4750:    Input Parameter:
4751: .  snes - the SNES context

4753:    Output Parameter:
4754: +  r - the vector that is used to store residuals (or NULL if you don't want it)
4755: .  f - the function (or NULL if you don't want it); see SNESFunction for calling sequence details
4756: -  ctx - the function context (or NULL if you don't want it)

4758:    Level: advanced

4760:     Notes: The vector r DOES NOT, in general contain the current value of the SNES nonlinear function

4762: .seealso: SNESSetFunction(), SNESGetSolution(), SNESFunction
4763: @*/
4764: PetscErrorCode  SNESGetFunction(SNES snes,Vec *r,PetscErrorCode (**f)(SNES,Vec,Vec,void*),void **ctx)
4765: {
4767:   DM             dm;

4771:   if (r) {
4772:     if (!snes->vec_func) {
4773:       if (snes->vec_rhs) {
4774:         VecDuplicate(snes->vec_rhs,&snes->vec_func);
4775:       } else if (snes->vec_sol) {
4776:         VecDuplicate(snes->vec_sol,&snes->vec_func);
4777:       } else if (snes->dm) {
4778:         DMCreateGlobalVector(snes->dm,&snes->vec_func);
4779:       }
4780:     }
4781:     *r = snes->vec_func;
4782:   }
4783:   SNESGetDM(snes,&dm);
4784:   DMSNESGetFunction(dm,f,ctx);
4785:   return(0);
4786: }

4788: /*@C
4789:    SNESGetNGS - Returns the NGS function and context.

4791:    Input Parameter:
4792: .  snes - the SNES context

4794:    Output Parameter:
4795: +  f - the function (or NULL) see SNESNGSFunction for details
4796: -  ctx    - the function context (or NULL)

4798:    Level: advanced

4800: .seealso: SNESSetNGS(), SNESGetFunction()
4801: @*/

4803: PetscErrorCode SNESGetNGS (SNES snes, PetscErrorCode (**f)(SNES, Vec, Vec, void*), void ** ctx)
4804: {
4806:   DM             dm;

4810:   SNESGetDM(snes,&dm);
4811:   DMSNESGetNGS(dm,f,ctx);
4812:   return(0);
4813: }

4815: /*@C
4816:    SNESSetOptionsPrefix - Sets the prefix used for searching for all
4817:    SNES options in the database.

4819:    Logically Collective on SNES

4821:    Input Parameter:
4822: +  snes - the SNES context
4823: -  prefix - the prefix to prepend to all option names

4825:    Notes:
4826:    A hyphen (-) must NOT be given at the beginning of the prefix name.
4827:    The first character of all runtime options is AUTOMATICALLY the hyphen.

4829:    Level: advanced

4831: .seealso: SNESSetFromOptions()
4832: @*/
4833: PetscErrorCode  SNESSetOptionsPrefix(SNES snes,const char prefix[])
4834: {

4839:   PetscObjectSetOptionsPrefix((PetscObject)snes,prefix);
4840:   if (!snes->ksp) {SNESGetKSP(snes,&snes->ksp);}
4841:   if (snes->linesearch) {
4842:     SNESGetLineSearch(snes,&snes->linesearch);
4843:     PetscObjectSetOptionsPrefix((PetscObject)snes->linesearch,prefix);
4844:   }
4845:   KSPSetOptionsPrefix(snes->ksp,prefix);
4846:   return(0);
4847: }

4849: /*@C
4850:    SNESAppendOptionsPrefix - Appends to the prefix used for searching for all
4851:    SNES options in the database.

4853:    Logically Collective on SNES

4855:    Input Parameters:
4856: +  snes - the SNES context
4857: -  prefix - the prefix to prepend to all option names

4859:    Notes:
4860:    A hyphen (-) must NOT be given at the beginning of the prefix name.
4861:    The first character of all runtime options is AUTOMATICALLY the hyphen.

4863:    Level: advanced

4865: .seealso: SNESGetOptionsPrefix()
4866: @*/
4867: PetscErrorCode  SNESAppendOptionsPrefix(SNES snes,const char prefix[])
4868: {

4873:   PetscObjectAppendOptionsPrefix((PetscObject)snes,prefix);
4874:   if (!snes->ksp) {SNESGetKSP(snes,&snes->ksp);}
4875:   if (snes->linesearch) {
4876:     SNESGetLineSearch(snes,&snes->linesearch);
4877:     PetscObjectAppendOptionsPrefix((PetscObject)snes->linesearch,prefix);
4878:   }
4879:   KSPAppendOptionsPrefix(snes->ksp,prefix);
4880:   return(0);
4881: }

4883: /*@C
4884:    SNESGetOptionsPrefix - Sets the prefix used for searching for all
4885:    SNES options in the database.

4887:    Not Collective

4889:    Input Parameter:
4890: .  snes - the SNES context

4892:    Output Parameter:
4893: .  prefix - pointer to the prefix string used

4895:    Notes:
4896:     On the fortran side, the user should pass in a string 'prefix' of
4897:    sufficient length to hold the prefix.

4899:    Level: advanced

4901: .seealso: SNESAppendOptionsPrefix()
4902: @*/
4903: PetscErrorCode  SNESGetOptionsPrefix(SNES snes,const char *prefix[])
4904: {

4909:   PetscObjectGetOptionsPrefix((PetscObject)snes,prefix);
4910:   return(0);
4911: }


4914: /*@C
4915:   SNESRegister - Adds a method to the nonlinear solver package.

4917:    Not collective

4919:    Input Parameters:
4920: +  name_solver - name of a new user-defined solver
4921: -  routine_create - routine to create method context

4923:    Notes:
4924:    SNESRegister() may be called multiple times to add several user-defined solvers.

4926:    Sample usage:
4927: .vb
4928:    SNESRegister("my_solver",MySolverCreate);
4929: .ve

4931:    Then, your solver can be chosen with the procedural interface via
4932: $     SNESSetType(snes,"my_solver")
4933:    or at runtime via the option
4934: $     -snes_type my_solver

4936:    Level: advanced

4938:     Note: If your function is not being put into a shared library then use SNESRegister() instead

4940: .seealso: SNESRegisterAll(), SNESRegisterDestroy()

4942:   Level: advanced
4943: @*/
4944: PetscErrorCode  SNESRegister(const char sname[],PetscErrorCode (*function)(SNES))
4945: {

4949:   SNESInitializePackage();
4950:   PetscFunctionListAdd(&SNESList,sname,function);
4951:   return(0);
4952: }

4954: PetscErrorCode  SNESTestLocalMin(SNES snes)
4955: {
4957:   PetscInt       N,i,j;
4958:   Vec            u,uh,fh;
4959:   PetscScalar    value;
4960:   PetscReal      norm;

4963:   SNESGetSolution(snes,&u);
4964:   VecDuplicate(u,&uh);
4965:   VecDuplicate(u,&fh);

4967:   /* currently only works for sequential */
4968:   PetscPrintf(PetscObjectComm((PetscObject)snes),"Testing FormFunction() for local min\n");
4969:   VecGetSize(u,&N);
4970:   for (i=0; i<N; i++) {
4971:     VecCopy(u,uh);
4972:     PetscPrintf(PetscObjectComm((PetscObject)snes),"i = %D\n",i);
4973:     for (j=-10; j<11; j++) {
4974:       value = PetscSign(j)*PetscExpReal(PetscAbs(j)-10.0);
4975:       VecSetValue(uh,i,value,ADD_VALUES);
4976:       SNESComputeFunction(snes,uh,fh);
4977:       VecNorm(fh,NORM_2,&norm);
4978:       PetscPrintf(PetscObjectComm((PetscObject)snes),"       j norm %D %18.16e\n",j,norm);
4979:       value = -value;
4980:       VecSetValue(uh,i,value,ADD_VALUES);
4981:     }
4982:   }
4983:   VecDestroy(&uh);
4984:   VecDestroy(&fh);
4985:   return(0);
4986: }

4988: /*@
4989:    SNESKSPSetUseEW - Sets SNES use Eisenstat-Walker method for
4990:    computing relative tolerance for linear solvers within an inexact
4991:    Newton method.

4993:    Logically Collective on SNES

4995:    Input Parameters:
4996: +  snes - SNES context
4997: -  flag - PETSC_TRUE or PETSC_FALSE

4999:     Options Database:
5000: +  -snes_ksp_ew - use Eisenstat-Walker method for determining linear system convergence
5001: .  -snes_ksp_ew_version ver - version of  Eisenstat-Walker method
5002: .  -snes_ksp_ew_rtol0 <rtol0> - Sets rtol0
5003: .  -snes_ksp_ew_rtolmax <rtolmax> - Sets rtolmax
5004: .  -snes_ksp_ew_gamma <gamma> - Sets gamma
5005: .  -snes_ksp_ew_alpha <alpha> - Sets alpha
5006: .  -snes_ksp_ew_alpha2 <alpha2> - Sets alpha2
5007: -  -snes_ksp_ew_threshold <threshold> - Sets threshold

5009:    Notes:
5010:    Currently, the default is to use a constant relative tolerance for
5011:    the inner linear solvers.  Alternatively, one can use the
5012:    Eisenstat-Walker method, where the relative convergence tolerance
5013:    is reset at each Newton iteration according progress of the nonlinear
5014:    solver.

5016:    Level: advanced

5018:    Reference:
5019:    S. C. Eisenstat and H. F. Walker, "Choosing the forcing terms in an
5020:    inexact Newton method", SISC 17 (1), pp.16-32, 1996.

5022: .seealso: SNESKSPGetUseEW(), SNESKSPGetParametersEW(), SNESKSPSetParametersEW()
5023: @*/
5024: PetscErrorCode  SNESKSPSetUseEW(SNES snes,PetscBool flag)
5025: {
5029:   snes->ksp_ewconv = flag;
5030:   return(0);
5031: }

5033: /*@
5034:    SNESKSPGetUseEW - Gets if SNES is using Eisenstat-Walker method
5035:    for computing relative tolerance for linear solvers within an
5036:    inexact Newton method.

5038:    Not Collective

5040:    Input Parameter:
5041: .  snes - SNES context

5043:    Output Parameter:
5044: .  flag - PETSC_TRUE or PETSC_FALSE

5046:    Notes:
5047:    Currently, the default is to use a constant relative tolerance for
5048:    the inner linear solvers.  Alternatively, one can use the
5049:    Eisenstat-Walker method, where the relative convergence tolerance
5050:    is reset at each Newton iteration according progress of the nonlinear
5051:    solver.

5053:    Level: advanced

5055:    Reference:
5056:    S. C. Eisenstat and H. F. Walker, "Choosing the forcing terms in an
5057:    inexact Newton method", SISC 17 (1), pp.16-32, 1996.

5059: .seealso: SNESKSPSetUseEW(), SNESKSPGetParametersEW(), SNESKSPSetParametersEW()
5060: @*/
5061: PetscErrorCode  SNESKSPGetUseEW(SNES snes, PetscBool  *flag)
5062: {
5066:   *flag = snes->ksp_ewconv;
5067:   return(0);
5068: }

5070: /*@
5071:    SNESKSPSetParametersEW - Sets parameters for Eisenstat-Walker
5072:    convergence criteria for the linear solvers within an inexact
5073:    Newton method.

5075:    Logically Collective on SNES

5077:    Input Parameters:
5078: +    snes - SNES context
5079: .    version - version 1, 2 (default is 2) or 3
5080: .    rtol_0 - initial relative tolerance (0 <= rtol_0 < 1)
5081: .    rtol_max - maximum relative tolerance (0 <= rtol_max < 1)
5082: .    gamma - multiplicative factor for version 2 rtol computation
5083:              (0 <= gamma2 <= 1)
5084: .    alpha - power for version 2 rtol computation (1 < alpha <= 2)
5085: .    alpha2 - power for safeguard
5086: -    threshold - threshold for imposing safeguard (0 < threshold < 1)

5088:    Note:
5089:    Version 3 was contributed by Luis Chacon, June 2006.

5091:    Use PETSC_DEFAULT to retain the default for any of the parameters.

5093:    Level: advanced

5095:    Reference:
5096:    S. C. Eisenstat and H. F. Walker, "Choosing the forcing terms in an
5097:    inexact Newton method", Utah State University Math. Stat. Dept. Res.
5098:    Report 6/94/75, June, 1994, to appear in SIAM J. Sci. Comput.

5100: .seealso: SNESKSPSetUseEW(), SNESKSPGetUseEW(), SNESKSPGetParametersEW()
5101: @*/
5102: PetscErrorCode  SNESKSPSetParametersEW(SNES snes,PetscInt version,PetscReal rtol_0,PetscReal rtol_max,PetscReal gamma,PetscReal alpha,PetscReal alpha2,PetscReal threshold)
5103: {
5104:   SNESKSPEW *kctx;

5108:   kctx = (SNESKSPEW*)snes->kspconvctx;
5109:   if (!kctx) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_WRONGSTATE,"No Eisenstat-Walker context existing");

5118:   if (version != PETSC_DEFAULT)   kctx->version   = version;
5119:   if (rtol_0 != PETSC_DEFAULT)    kctx->rtol_0    = rtol_0;
5120:   if (rtol_max != PETSC_DEFAULT)  kctx->rtol_max  = rtol_max;
5121:   if (gamma != PETSC_DEFAULT)     kctx->gamma     = gamma;
5122:   if (alpha != PETSC_DEFAULT)     kctx->alpha     = alpha;
5123:   if (alpha2 != PETSC_DEFAULT)    kctx->alpha2    = alpha2;
5124:   if (threshold != PETSC_DEFAULT) kctx->threshold = threshold;

5126:   if (kctx->version < 1 || kctx->version > 3) SETERRQ1(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"Only versions 1, 2 and 3 are supported: %D",kctx->version);
5127:   if (kctx->rtol_0 < 0.0 || kctx->rtol_0 >= 1.0) SETERRQ1(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"0.0 <= rtol_0 < 1.0: %g",(double)kctx->rtol_0);
5128:   if (kctx->rtol_max < 0.0 || kctx->rtol_max >= 1.0) SETERRQ1(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"0.0 <= rtol_max (%g) < 1.0\n",(double)kctx->rtol_max);
5129:   if (kctx->gamma < 0.0 || kctx->gamma > 1.0) SETERRQ1(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"0.0 <= gamma (%g) <= 1.0\n",(double)kctx->gamma);
5130:   if (kctx->alpha <= 1.0 || kctx->alpha > 2.0) SETERRQ1(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"1.0 < alpha (%g) <= 2.0\n",(double)kctx->alpha);
5131:   if (kctx->threshold <= 0.0 || kctx->threshold >= 1.0) SETERRQ1(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"0.0 < threshold (%g) < 1.0\n",(double)kctx->threshold);
5132:   return(0);
5133: }

5135: /*@
5136:    SNESKSPGetParametersEW - Gets parameters for Eisenstat-Walker
5137:    convergence criteria for the linear solvers within an inexact
5138:    Newton method.

5140:    Not Collective

5142:    Input Parameters:
5143:      snes - SNES context

5145:    Output Parameters:
5146: +    version - version 1, 2 (default is 2) or 3
5147: .    rtol_0 - initial relative tolerance (0 <= rtol_0 < 1)
5148: .    rtol_max - maximum relative tolerance (0 <= rtol_max < 1)
5149: .    gamma - multiplicative factor for version 2 rtol computation (0 <= gamma2 <= 1)
5150: .    alpha - power for version 2 rtol computation (1 < alpha <= 2)
5151: .    alpha2 - power for safeguard
5152: -    threshold - threshold for imposing safeguard (0 < threshold < 1)

5154:    Level: advanced

5156: .seealso: SNESKSPSetUseEW(), SNESKSPGetUseEW(), SNESKSPSetParametersEW()
5157: @*/
5158: PetscErrorCode  SNESKSPGetParametersEW(SNES snes,PetscInt *version,PetscReal *rtol_0,PetscReal *rtol_max,PetscReal *gamma,PetscReal *alpha,PetscReal *alpha2,PetscReal *threshold)
5159: {
5160:   SNESKSPEW *kctx;

5164:   kctx = (SNESKSPEW*)snes->kspconvctx;
5165:   if (!kctx) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_WRONGSTATE,"No Eisenstat-Walker context existing");
5166:   if (version)   *version   = kctx->version;
5167:   if (rtol_0)    *rtol_0    = kctx->rtol_0;
5168:   if (rtol_max)  *rtol_max  = kctx->rtol_max;
5169:   if (gamma)     *gamma     = kctx->gamma;
5170:   if (alpha)     *alpha     = kctx->alpha;
5171:   if (alpha2)    *alpha2    = kctx->alpha2;
5172:   if (threshold) *threshold = kctx->threshold;
5173:   return(0);
5174: }

5176:  PetscErrorCode KSPPreSolve_SNESEW(KSP ksp, Vec b, Vec x, SNES snes)
5177: {
5179:   SNESKSPEW      *kctx = (SNESKSPEW*)snes->kspconvctx;
5180:   PetscReal      rtol  = PETSC_DEFAULT,stol;

5183:   if (!snes->ksp_ewconv) return(0);
5184:   if (!snes->iter) {
5185:     rtol = kctx->rtol_0; /* first time in, so use the original user rtol */
5186:     VecNorm(snes->vec_func,NORM_2,&kctx->norm_first);
5187:   }
5188:   else {
5189:     if (kctx->version == 1) {
5190:       rtol = (snes->norm - kctx->lresid_last)/kctx->norm_last;
5191:       if (rtol < 0.0) rtol = -rtol;
5192:       stol = PetscPowReal(kctx->rtol_last,kctx->alpha2);
5193:       if (stol > kctx->threshold) rtol = PetscMax(rtol,stol);
5194:     } else if (kctx->version == 2) {
5195:       rtol = kctx->gamma * PetscPowReal(snes->norm/kctx->norm_last,kctx->alpha);
5196:       stol = kctx->gamma * PetscPowReal(kctx->rtol_last,kctx->alpha);
5197:       if (stol > kctx->threshold) rtol = PetscMax(rtol,stol);
5198:     } else if (kctx->version == 3) { /* contributed by Luis Chacon, June 2006. */
5199:       rtol = kctx->gamma * PetscPowReal(snes->norm/kctx->norm_last,kctx->alpha);
5200:       /* safeguard: avoid sharp decrease of rtol */
5201:       stol = kctx->gamma*PetscPowReal(kctx->rtol_last,kctx->alpha);
5202:       stol = PetscMax(rtol,stol);
5203:       rtol = PetscMin(kctx->rtol_0,stol);
5204:       /* safeguard: avoid oversolving */
5205:       stol = kctx->gamma*(kctx->norm_first*snes->rtol)/snes->norm;
5206:       stol = PetscMax(rtol,stol);
5207:       rtol = PetscMin(kctx->rtol_0,stol);
5208:     } else SETERRQ1(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"Only versions 1, 2 or 3 are supported: %D",kctx->version);
5209:   }
5210:   /* safeguard: avoid rtol greater than one */
5211:   rtol = PetscMin(rtol,kctx->rtol_max);
5212:   KSPSetTolerances(ksp,rtol,PETSC_DEFAULT,PETSC_DEFAULT,PETSC_DEFAULT);
5213:   PetscInfo3(snes,"iter %D, Eisenstat-Walker (version %D) KSP rtol=%g\n",snes->iter,kctx->version,(double)rtol);
5214:   return(0);
5215: }

5217: PetscErrorCode KSPPostSolve_SNESEW(KSP ksp, Vec b, Vec x, SNES snes)
5218: {
5220:   SNESKSPEW      *kctx = (SNESKSPEW*)snes->kspconvctx;
5221:   PCSide         pcside;
5222:   Vec            lres;

5225:   if (!snes->ksp_ewconv) return(0);
5226:   KSPGetTolerances(ksp,&kctx->rtol_last,NULL,NULL,NULL);
5227:   kctx->norm_last = snes->norm;
5228:   if (kctx->version == 1) {
5229:     PC        pc;
5230:     PetscBool isNone;

5232:     KSPGetPC(ksp, &pc);
5233:     PetscObjectTypeCompare((PetscObject) pc, PCNONE, &isNone);
5234:     KSPGetPCSide(ksp,&pcside);
5235:      if (pcside == PC_RIGHT || isNone) { /* XXX Should we also test KSP_UNPRECONDITIONED_NORM ? */
5236:       /* KSP residual is true linear residual */
5237:       KSPGetResidualNorm(ksp,&kctx->lresid_last);
5238:     } else {
5239:       /* KSP residual is preconditioned residual */
5240:       /* compute true linear residual norm */
5241:       VecDuplicate(b,&lres);
5242:       MatMult(snes->jacobian,x,lres);
5243:       VecAYPX(lres,-1.0,b);
5244:       VecNorm(lres,NORM_2,&kctx->lresid_last);
5245:       VecDestroy(&lres);
5246:     }
5247:   }
5248:   return(0);
5249: }

5251: /*@
5252:    SNESGetKSP - Returns the KSP context for a SNES solver.

5254:    Not Collective, but if SNES object is parallel, then KSP object is parallel

5256:    Input Parameter:
5257: .  snes - the SNES context

5259:    Output Parameter:
5260: .  ksp - the KSP context

5262:    Notes:
5263:    The user can then directly manipulate the KSP context to set various
5264:    options, etc.  Likewise, the user can then extract and manipulate the
5265:    PC contexts as well.

5267:    Level: beginner

5269: .seealso: KSPGetPC(), SNESCreate(), KSPCreate(), SNESSetKSP()
5270: @*/
5271: PetscErrorCode  SNESGetKSP(SNES snes,KSP *ksp)
5272: {


5279:   if (!snes->ksp) {
5280:     PetscBool monitor = PETSC_FALSE;

5282:     KSPCreate(PetscObjectComm((PetscObject)snes),&snes->ksp);
5283:     PetscObjectIncrementTabLevel((PetscObject)snes->ksp,(PetscObject)snes,1);
5284:     PetscLogObjectParent((PetscObject)snes,(PetscObject)snes->ksp);

5286:     KSPSetPreSolve(snes->ksp,(PetscErrorCode (*)(KSP,Vec,Vec,void*))KSPPreSolve_SNESEW,snes);
5287:     KSPSetPostSolve(snes->ksp,(PetscErrorCode (*)(KSP,Vec,Vec,void*))KSPPostSolve_SNESEW,snes);

5289:     PetscOptionsGetBool(((PetscObject)snes)->options,((PetscObject)snes)->prefix,"-ksp_monitor_snes",&monitor,NULL);
5290:     if (monitor) {
5291:       KSPMonitorSet(snes->ksp,KSPMonitorSNES,snes,NULL);
5292:     }
5293:     monitor = PETSC_FALSE;
5294:     PetscOptionsGetBool(((PetscObject)snes)->options,((PetscObject)snes)->prefix,"-ksp_monitor_snes_lg",&monitor,NULL);
5295:     if (monitor) {
5296:       PetscObject *objs;
5297:       KSPMonitorSNESLGResidualNormCreate(PetscObjectComm((PetscObject)snes),NULL,NULL,PETSC_DECIDE,PETSC_DECIDE,600,600,&objs);
5298:       objs[0] = (PetscObject) snes;
5299:       KSPMonitorSet(snes->ksp,(PetscErrorCode (*)(KSP,PetscInt,PetscReal,void*))KSPMonitorSNESLGResidualNorm,objs,(PetscErrorCode (*)(void**))KSPMonitorSNESLGResidualNormDestroy);
5300:     }
5301:     PetscObjectSetOptions((PetscObject)snes->ksp,((PetscObject)snes)->options);
5302:   }
5303:   *ksp = snes->ksp;
5304:   return(0);
5305: }


5308:  #include <petsc/private/dmimpl.h>
5309: /*@
5310:    SNESSetDM - Sets the DM that may be used by some nonlinear solvers or their underlying preconditioners

5312:    Logically Collective on SNES

5314:    Input Parameters:
5315: +  snes - the nonlinear solver context
5316: -  dm - the dm, cannot be NULL

5318:    Notes:
5319:    A DM can only be used for solving one problem at a time because information about the problem is stored on the DM,
5320:    even when not using interfaces like DMSNESSetFunction().  Use DMClone() to get a distinct DM when solving different
5321:    problems using the same function space.

5323:    Level: intermediate

5325: .seealso: SNESGetDM(), KSPSetDM(), KSPGetDM()
5326: @*/
5327: PetscErrorCode  SNESSetDM(SNES snes,DM dm)
5328: {
5330:   KSP            ksp;
5331:   DMSNES         sdm;

5336:   PetscObjectReference((PetscObject)dm);
5337:   if (snes->dm) {               /* Move the DMSNES context over to the new DM unless the new DM already has one */
5338:     if (snes->dm->dmsnes && !dm->dmsnes) {
5339:       DMCopyDMSNES(snes->dm,dm);
5340:       DMGetDMSNES(snes->dm,&sdm);
5341:       if (sdm->originaldm == snes->dm) sdm->originaldm = dm; /* Grant write privileges to the replacement DM */
5342:     }
5343:     DMCoarsenHookRemove(snes->dm,DMCoarsenHook_SNESVecSol,DMRestrictHook_SNESVecSol,snes);
5344:     DMDestroy(&snes->dm);
5345:   }
5346:   snes->dm     = dm;
5347:   snes->dmAuto = PETSC_FALSE;

5349:   SNESGetKSP(snes,&ksp);
5350:   KSPSetDM(ksp,dm);
5351:   KSPSetDMActive(ksp,PETSC_FALSE);
5352:   if (snes->npc) {
5353:     SNESSetDM(snes->npc, snes->dm);
5354:     SNESSetNPCSide(snes,snes->npcside);
5355:   }
5356:   return(0);
5357: }

5359: /*@
5360:    SNESGetDM - Gets the DM that may be used by some preconditioners

5362:    Not Collective but DM obtained is parallel on SNES

5364:    Input Parameter:
5365: . snes - the preconditioner context

5367:    Output Parameter:
5368: .  dm - the dm

5370:    Level: intermediate

5372: .seealso: SNESSetDM(), KSPSetDM(), KSPGetDM()
5373: @*/
5374: PetscErrorCode  SNESGetDM(SNES snes,DM *dm)
5375: {

5380:   if (!snes->dm) {
5381:     DMShellCreate(PetscObjectComm((PetscObject)snes),&snes->dm);
5382:     snes->dmAuto = PETSC_TRUE;
5383:   }
5384:   *dm = snes->dm;
5385:   return(0);
5386: }

5388: /*@
5389:   SNESSetNPC - Sets the nonlinear preconditioner to be used.

5391:   Collective on SNES

5393:   Input Parameters:
5394: + snes - iterative context obtained from SNESCreate()
5395: - pc   - the preconditioner object

5397:   Notes:
5398:   Use SNESGetNPC() to retrieve the preconditioner context (for example,
5399:   to configure it using the API).

5401:   Level: developer

5403: .seealso: SNESGetNPC(), SNESHasNPC()
5404: @*/
5405: PetscErrorCode SNESSetNPC(SNES snes, SNES pc)
5406: {

5413:   PetscObjectReference((PetscObject) pc);
5414:   SNESDestroy(&snes->npc);
5415:   snes->npc = pc;
5416:   PetscLogObjectParent((PetscObject)snes, (PetscObject)snes->npc);
5417:   return(0);
5418: }

5420: /*@
5421:   SNESGetNPC - Creates a nonlinear preconditioning solver (SNES) to be used to precondition the nonlinear solver.

5423:   Not Collective; but any changes to the obtained SNES object must be applied collectively

5425:   Input Parameter:
5426: . snes - iterative context obtained from SNESCreate()

5428:   Output Parameter:
5429: . pc - preconditioner context

5431:   Options Database:
5432: . -npc_snes_type <type> - set the type of the SNES to use as the nonlinear preconditioner

5434:   Notes:
5435:     If a SNES was previously set with SNESSetNPC() then that SNES is returned, otherwise a new SNES object is created.

5437:     The (preconditioner) SNES returned automatically inherits the same nonlinear function and Jacobian supplied to the original
5438:     SNES during SNESSetUp()

5440:   Level: developer

5442: .seealso: SNESSetNPC(), SNESHasNPC(), SNES, SNESCreate()
5443: @*/
5444: PetscErrorCode SNESGetNPC(SNES snes, SNES *pc)
5445: {
5447:   const char     *optionsprefix;

5452:   if (!snes->npc) {
5453:     SNESCreate(PetscObjectComm((PetscObject)snes),&snes->npc);
5454:     PetscObjectIncrementTabLevel((PetscObject)snes->npc,(PetscObject)snes,1);
5455:     PetscLogObjectParent((PetscObject)snes,(PetscObject)snes->npc);
5456:     SNESGetOptionsPrefix(snes,&optionsprefix);
5457:     SNESSetOptionsPrefix(snes->npc,optionsprefix);
5458:     SNESAppendOptionsPrefix(snes->npc,"npc_");
5459:     SNESSetCountersReset(snes->npc,PETSC_FALSE);
5460:   }
5461:   *pc = snes->npc;
5462:   return(0);
5463: }

5465: /*@
5466:   SNESHasNPC - Returns whether a nonlinear preconditioner exists

5468:   Not Collective

5470:   Input Parameter:
5471: . snes - iterative context obtained from SNESCreate()

5473:   Output Parameter:
5474: . has_npc - whether the SNES has an NPC or not

5476:   Level: developer

5478: .seealso: SNESSetNPC(), SNESGetNPC()
5479: @*/
5480: PetscErrorCode SNESHasNPC(SNES snes, PetscBool *has_npc)
5481: {
5484:   *has_npc = (PetscBool) (snes->npc ? PETSC_TRUE : PETSC_FALSE);
5485:   return(0);
5486: }

5488: /*@
5489:     SNESSetNPCSide - Sets the preconditioning side.

5491:     Logically Collective on SNES

5493:     Input Parameter:
5494: .   snes - iterative context obtained from SNESCreate()

5496:     Output Parameter:
5497: .   side - the preconditioning side, where side is one of
5498: .vb
5499:       PC_LEFT - left preconditioning
5500:       PC_RIGHT - right preconditioning (default for most nonlinear solvers)
5501: .ve

5503:     Options Database Keys:
5504: .   -snes_pc_side <right,left>

5506:     Notes:
5507:     SNESNRICHARDSON and SNESNCG only support left preconditioning.

5509:     Level: intermediate

5511: .seealso: SNESGetNPCSide(), KSPSetPCSide()
5512: @*/
5513: PetscErrorCode  SNESSetNPCSide(SNES snes,PCSide side)
5514: {
5518:   snes->npcside= side;
5519:   return(0);
5520: }

5522: /*@
5523:     SNESGetNPCSide - Gets the preconditioning side.

5525:     Not Collective

5527:     Input Parameter:
5528: .   snes - iterative context obtained from SNESCreate()

5530:     Output Parameter:
5531: .   side - the preconditioning side, where side is one of
5532: .vb
5533:       PC_LEFT - left preconditioning
5534:       PC_RIGHT - right preconditioning (default for most nonlinear solvers)
5535: .ve

5537:     Level: intermediate

5539: .seealso: SNESSetNPCSide(), KSPGetPCSide()
5540: @*/
5541: PetscErrorCode  SNESGetNPCSide(SNES snes,PCSide *side)
5542: {
5546:   *side = snes->npcside;
5547:   return(0);
5548: }

5550: /*@
5551:   SNESSetLineSearch - Sets the linesearch on the SNES instance.

5553:   Collective on SNES

5555:   Input Parameters:
5556: + snes - iterative context obtained from SNESCreate()
5557: - linesearch   - the linesearch object

5559:   Notes:
5560:   Use SNESGetLineSearch() to retrieve the preconditioner context (for example,
5561:   to configure it using the API).

5563:   Level: developer

5565: .seealso: SNESGetLineSearch()
5566: @*/
5567: PetscErrorCode SNESSetLineSearch(SNES snes, SNESLineSearch linesearch)
5568: {

5575:   PetscObjectReference((PetscObject) linesearch);
5576:   SNESLineSearchDestroy(&snes->linesearch);

5578:   snes->linesearch = linesearch;

5580:   PetscLogObjectParent((PetscObject)snes, (PetscObject)snes->linesearch);
5581:   return(0);
5582: }

5584: /*@
5585:   SNESGetLineSearch - Returns a pointer to the line search context set with SNESSetLineSearch()
5586:   or creates a default line search instance associated with the SNES and returns it.

5588:   Not Collective

5590:   Input Parameter:
5591: . snes - iterative context obtained from SNESCreate()

5593:   Output Parameter:
5594: . linesearch - linesearch context

5596:   Level: beginner

5598: .seealso: SNESSetLineSearch(), SNESLineSearchCreate()
5599: @*/
5600: PetscErrorCode SNESGetLineSearch(SNES snes, SNESLineSearch *linesearch)
5601: {
5603:   const char     *optionsprefix;

5608:   if (!snes->linesearch) {
5609:     SNESGetOptionsPrefix(snes, &optionsprefix);
5610:     SNESLineSearchCreate(PetscObjectComm((PetscObject)snes), &snes->linesearch);
5611:     SNESLineSearchSetSNES(snes->linesearch, snes);
5612:     SNESLineSearchAppendOptionsPrefix(snes->linesearch, optionsprefix);
5613:     PetscObjectIncrementTabLevel((PetscObject) snes->linesearch, (PetscObject) snes, 1);
5614:     PetscLogObjectParent((PetscObject)snes, (PetscObject)snes->linesearch);
5615:   }
5616:   *linesearch = snes->linesearch;
5617:   return(0);
5618: }