Actual source code: itcreate.c

petsc-3.10.3 2018-12-18
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  2: /*
  3:      The basic KSP routines, Create, View etc. are here.
  4: */
  5:  #include <petsc/private/kspimpl.h>

  7: /* Logging support */
  8: PetscClassId  KSP_CLASSID;
  9: PetscClassId  DMKSP_CLASSID;
 10: PetscClassId  KSPGUESS_CLASSID;
 11: PetscLogEvent KSP_GMRESOrthogonalization, KSP_SetUp, KSP_Solve;

 13: /*
 14:    Contains the list of registered KSP routines
 15: */
 16: PetscFunctionList KSPList              = 0;
 17: PetscBool         KSPRegisterAllCalled = PETSC_FALSE;

 19: /*@C
 20:   KSPLoad - Loads a KSP that has been stored in binary  with KSPView().

 22:   Collective on PetscViewer

 24:   Input Parameters:
 25: + newdm - the newly loaded KSP, this needs to have been created with KSPCreate() or
 26:            some related function before a call to KSPLoad().
 27: - viewer - binary file viewer, obtained from PetscViewerBinaryOpen()

 29:    Level: intermediate

 31:   Notes:
 32:    The type is determined by the data in the file, any type set into the KSP before this call is ignored.

 34:   Notes for advanced users:
 35:   Most users should not need to know the details of the binary storage
 36:   format, since KSPLoad() and KSPView() completely hide these details.
 37:   But for anyone who's interested, the standard binary matrix storage
 38:   format is
 39: .vb
 40:      has not yet been determined
 41: .ve

 43: .seealso: PetscViewerBinaryOpen(), KSPView(), MatLoad(), VecLoad()
 44: @*/
 45: PetscErrorCode  KSPLoad(KSP newdm, PetscViewer viewer)
 46: {
 48:   PetscBool      isbinary;
 49:   PetscInt       classid;
 50:   char           type[256];
 51:   PC             pc;

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

 59:   PetscViewerBinaryRead(viewer,&classid,1,NULL,PETSC_INT);
 60:   if (classid != KSP_FILE_CLASSID) SETERRQ(PetscObjectComm((PetscObject)newdm),PETSC_ERR_ARG_WRONG,"Not KSP next in file");
 61:   PetscViewerBinaryRead(viewer,type,256,NULL,PETSC_CHAR);
 62:   KSPSetType(newdm, type);
 63:   if (newdm->ops->load) {
 64:     (*newdm->ops->load)(newdm,viewer);
 65:   }
 66:   KSPGetPC(newdm,&pc);
 67:   PCLoad(pc,viewer);
 68:   return(0);
 69: }

 71:  #include <petscdraw.h>
 72: #if defined(PETSC_HAVE_SAWS)
 73:  #include <petscviewersaws.h>
 74: #endif
 75: /*@C
 76:    KSPView - Prints the KSP data structure.

 78:    Collective on KSP

 80:    Input Parameters:
 81: +  ksp - the Krylov space context
 82: -  viewer - visualization context

 84:    Options Database Keys:
 85: .  -ksp_view - print the ksp data structure at the end of a KSPSolve call

 87:    Note:
 88:    The available visualization contexts include
 89: +     PETSC_VIEWER_STDOUT_SELF - standard output (default)
 90: -     PETSC_VIEWER_STDOUT_WORLD - synchronized standard
 91:          output where only the first processor opens
 92:          the file.  All other processors send their
 93:          data to the first processor to print.

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

 98:    Level: beginner

100: .keywords: KSP, view

102: .seealso: PCView(), PetscViewerASCIIOpen()
103: @*/
104: PetscErrorCode  KSPView(KSP ksp,PetscViewer viewer)
105: {
107:   PetscBool      iascii,isbinary,isdraw;
108: #if defined(PETSC_HAVE_SAWS)
109:   PetscBool      issaws;
110: #endif

114:   if (!viewer) {
115:     PetscViewerASCIIGetStdout(PetscObjectComm((PetscObject)ksp),&viewer);
116:   }

120:   PetscObjectTypeCompare((PetscObject)viewer,PETSCVIEWERASCII,&iascii);
121:   PetscObjectTypeCompare((PetscObject)viewer,PETSCVIEWERBINARY,&isbinary);
122:   PetscObjectTypeCompare((PetscObject)viewer,PETSCVIEWERDRAW,&isdraw);
123: #if defined(PETSC_HAVE_SAWS)
124:   PetscObjectTypeCompare((PetscObject)viewer,PETSCVIEWERSAWS,&issaws);
125: #endif
126:   if (iascii) {
127:     PetscObjectPrintClassNamePrefixType((PetscObject)ksp,viewer);
128:     if (ksp->ops->view) {
129:       PetscViewerASCIIPushTab(viewer);
130:       (*ksp->ops->view)(ksp,viewer);
131:       PetscViewerASCIIPopTab(viewer);
132:     }
133:     if (ksp->guess_zero) {
134:       PetscViewerASCIIPrintf(viewer,"  maximum iterations=%D, initial guess is zero\n",ksp->max_it);
135:     } else {
136:       PetscViewerASCIIPrintf(viewer,"  maximum iterations=%D, nonzero initial guess\n", ksp->max_it);
137:     }
138:     if (ksp->guess_knoll) {PetscViewerASCIIPrintf(viewer,"  using preconditioner applied to right hand side for initial guess\n");}
139:     PetscViewerASCIIPrintf(viewer,"  tolerances:  relative=%g, absolute=%g, divergence=%g\n",(double)ksp->rtol,(double)ksp->abstol,(double)ksp->divtol);
140:     if (ksp->pc_side == PC_RIGHT) {
141:       PetscViewerASCIIPrintf(viewer,"  right preconditioning\n");
142:     } else if (ksp->pc_side == PC_SYMMETRIC) {
143:       PetscViewerASCIIPrintf(viewer,"  symmetric preconditioning\n");
144:     } else {
145:       PetscViewerASCIIPrintf(viewer,"  left preconditioning\n");
146:     }
147:     if (ksp->guess) {
148:       PetscViewerASCIIPushTab(viewer);
149:       KSPGuessView(ksp->guess,viewer);
150:       PetscViewerASCIIPopTab(viewer);
151:     }
152:     if (ksp->dscale) {PetscViewerASCIIPrintf(viewer,"  diagonally scaled system\n");}
153:     PetscViewerASCIIPrintf(viewer,"  using %s norm type for convergence test\n",KSPNormTypes[ksp->normtype]);
154:   } else if (isbinary) {
155:     PetscInt    classid = KSP_FILE_CLASSID;
156:     MPI_Comm    comm;
157:     PetscMPIInt rank;
158:     char        type[256];

160:     PetscObjectGetComm((PetscObject)ksp,&comm);
161:     MPI_Comm_rank(comm,&rank);
162:     if (!rank) {
163:       PetscViewerBinaryWrite(viewer,&classid,1,PETSC_INT,PETSC_FALSE);
164:       PetscStrncpy(type,((PetscObject)ksp)->type_name,256);
165:       PetscViewerBinaryWrite(viewer,type,256,PETSC_CHAR,PETSC_FALSE);
166:     }
167:     if (ksp->ops->view) {
168:       (*ksp->ops->view)(ksp,viewer);
169:     }
170:   } else if (isdraw) {
171:     PetscDraw draw;
172:     char      str[36];
173:     PetscReal x,y,bottom,h;
174:     PetscBool flg;

176:     PetscViewerDrawGetDraw(viewer,0,&draw);
177:     PetscDrawGetCurrentPoint(draw,&x,&y);
178:     PetscObjectTypeCompare((PetscObject)ksp,KSPPREONLY,&flg);
179:     if (!flg) {
180:       PetscStrncpy(str,"KSP: ",sizeof(str));
181:       PetscStrlcat(str,((PetscObject)ksp)->type_name,sizeof(str));
182:       PetscDrawStringBoxed(draw,x,y,PETSC_DRAW_RED,PETSC_DRAW_BLACK,str,NULL,&h);
183:       bottom = y - h;
184:     } else {
185:       bottom = y;
186:     }
187:     PetscDrawPushCurrentPoint(draw,x,bottom);
188: #if defined(PETSC_HAVE_SAWS)
189:   } else if (issaws) {
190:     PetscMPIInt rank;
191:     const char  *name;

193:     PetscObjectGetName((PetscObject)ksp,&name);
194:     MPI_Comm_rank(PETSC_COMM_WORLD,&rank);
195:     if (!((PetscObject)ksp)->amsmem && !rank) {
196:       char       dir[1024];

198:       PetscObjectViewSAWs((PetscObject)ksp,viewer);
199:       PetscSNPrintf(dir,1024,"/PETSc/Objects/%s/its",name);
200:       PetscStackCallSAWs(SAWs_Register,(dir,&ksp->its,1,SAWs_READ,SAWs_INT));
201:       if (!ksp->res_hist) {
202:         KSPSetResidualHistory(ksp,NULL,PETSC_DECIDE,PETSC_TRUE);
203:       }
204:       PetscSNPrintf(dir,1024,"/PETSc/Objects/%s/res_hist",name);
205:       PetscStackCallSAWs(SAWs_Register,(dir,ksp->res_hist,10,SAWs_READ,SAWs_DOUBLE));
206:     }
207: #endif
208:   } else if (ksp->ops->view) {
209:     (*ksp->ops->view)(ksp,viewer);
210:   }
211:   if (!ksp->skippcsetfromoptions) {
212:     if (!ksp->pc) {KSPGetPC(ksp,&ksp->pc);}
213:     PCView(ksp->pc,viewer);
214:   }
215:   if (isdraw) {
216:     PetscDraw draw;
217:     PetscViewerDrawGetDraw(viewer,0,&draw);
218:     PetscDrawPopCurrentPoint(draw);
219:   }
220:   return(0);
221: }


224: /*@
225:    KSPSetNormType - Sets the norm that is used for convergence testing.

227:    Logically Collective on KSP

229:    Input Parameter:
230: +  ksp - Krylov solver context
231: -  normtype - one of
232: $   KSP_NORM_NONE - skips computing the norm, this should only be used if you are using
233: $                 the Krylov method as a smoother with a fixed small number of iterations.
234: $                 Implicitly sets KSPConvergedSkip as KSP convergence test.
235: $   KSP_NORM_PRECONDITIONED - the default for left preconditioned solves, uses the l2 norm
236: $                 of the preconditioned residual P^{-1}(b - A x)
237: $   KSP_NORM_UNPRECONDITIONED - uses the l2 norm of the true b - Ax residual.
238: $   KSP_NORM_NATURAL - supported  by KSPCG, KSPCR, KSPCGNE, KSPCGS


241:    Options Database Key:
242: .   -ksp_norm_type <none,preconditioned,unpreconditioned,natural>

244:    Notes:
245:    Not all combinations of preconditioner side (see KSPSetPCSide()) and norm type are supported by all Krylov methods.
246:    If only one is set, PETSc tries to automatically change the other to find a compatible pair.  If no such combination
247:    is supported, PETSc will generate an error.

249:    Developer Notes:
250:    Supported combinations of norm and preconditioner side are set using KSPSetSupportedNorm().

252:    Level: advanced

254: .keywords: KSP, create, context, norms

256: .seealso: KSPSetUp(), KSPSolve(), KSPDestroy(), KSPConvergedSkip(), KSPSetCheckNormIteration(), KSPSetPCSide(), KSPGetPCSide(), KSPNormType
257: @*/
258: PetscErrorCode  KSPSetNormType(KSP ksp,KSPNormType normtype)
259: {
263:   ksp->normtype = ksp->normtype_set = normtype;
264:   return(0);
265: }

267: /*@
268:    KSPSetCheckNormIteration - Sets the first iteration at which the norm of the residual will be
269:      computed and used in the convergence test.

271:    Logically Collective on KSP

273:    Input Parameter:
274: +  ksp - Krylov solver context
275: -  it  - use -1 to check at all iterations

277:    Notes:
278:    Currently only works with KSPCG, KSPBCGS and KSPIBCGS

280:    Use KSPSetNormType(ksp,KSP_NORM_NONE) to never check the norm

282:    On steps where the norm is not computed, the previous norm is still in the variable, so if you run with, for example,
283:     -ksp_monitor the residual norm will appear to be unchanged for several iterations (though it is not really unchanged).
284:    Level: advanced

286: .keywords: KSP, create, context, norms

288: .seealso: KSPSetUp(), KSPSolve(), KSPDestroy(), KSPConvergedSkip(), KSPSetNormType()
289: @*/
290: PetscErrorCode  KSPSetCheckNormIteration(KSP ksp,PetscInt it)
291: {
295:   ksp->chknorm = it;
296:   return(0);
297: }

299: /*@
300:    KSPSetLagNorm - Lags the residual norm calculation so that it is computed as part of the MPI_Allreduce() for
301:    computing the inner products for the next iteration.  This can reduce communication costs at the expense of doing
302:    one additional iteration.


305:    Logically Collective on KSP

307:    Input Parameter:
308: +  ksp - Krylov solver context
309: -  flg - PETSC_TRUE or PETSC_FALSE

311:    Options Database Keys:
312: .  -ksp_lag_norm - lag the calculated residual norm

314:    Notes:
315:    Currently only works with KSPIBCGS.

317:    Use KSPSetNormType(ksp,KSP_NORM_NONE) to never check the norm

319:    If you lag the norm and run with, for example, -ksp_monitor, the residual norm reported will be the lagged one.
320:    Level: advanced

322: .keywords: KSP, create, context, norms

324: .seealso: KSPSetUp(), KSPSolve(), KSPDestroy(), KSPConvergedSkip(), KSPSetNormType(), KSPSetCheckNormIteration()
325: @*/
326: PetscErrorCode  KSPSetLagNorm(KSP ksp,PetscBool flg)
327: {
331:   ksp->lagnorm = flg;
332:   return(0);
333: }

335: /*@
336:    KSPSetSupportedNorm - Sets a norm and preconditioner side supported by a KSP

338:    Logically Collective

340:    Input Arguments:
341: +  ksp - Krylov method
342: .  normtype - supported norm type
343: .  pcside - preconditioner side that can be used with this norm
344: -  priority - positive integer preference for this combination; larger values have higher priority

346:    Level: developer

348:    Notes:
349:    This function should be called from the implementation files KSPCreate_XXX() to declare
350:    which norms and preconditioner sides are supported. Users should not need to call this
351:    function.

353: .seealso: KSPSetNormType(), KSPSetPCSide()
354: @*/
355: PetscErrorCode KSPSetSupportedNorm(KSP ksp,KSPNormType normtype,PCSide pcside,PetscInt priority)
356: {

360:   ksp->normsupporttable[normtype][pcside] = priority;
361:   return(0);
362: }

364: PetscErrorCode KSPNormSupportTableReset_Private(KSP ksp)
365: {

369:   PetscMemzero(ksp->normsupporttable,sizeof(ksp->normsupporttable));
370:   ksp->pc_side  = ksp->pc_side_set;
371:   ksp->normtype = ksp->normtype_set;
372:   return(0);
373: }

375: PetscErrorCode KSPSetUpNorms_Private(KSP ksp,PetscBool errorifnotsupported,KSPNormType *normtype,PCSide *pcside)
376: {
377:   PetscInt i,j,best,ibest = 0,jbest = 0;

380:   best = 0;
381:   for (i=0; i<KSP_NORM_MAX; i++) {
382:     for (j=0; j<PC_SIDE_MAX; j++) {
383:       if ((ksp->normtype == KSP_NORM_DEFAULT || ksp->normtype == i) && (ksp->pc_side == PC_SIDE_DEFAULT || ksp->pc_side == j) && (ksp->normsupporttable[i][j] > best)) {
384:         best  = ksp->normsupporttable[i][j];
385:         ibest = i;
386:         jbest = j;
387:       }
388:     }
389:   }
390:   if (best < 1 && errorifnotsupported) {
391:     if (ksp->normtype == KSP_NORM_DEFAULT && ksp->pc_side == PC_SIDE_DEFAULT) SETERRQ1(PetscObjectComm((PetscObject)ksp),PETSC_ERR_PLIB,"The %s KSP implementation did not call KSPSetSupportedNorm()",((PetscObject)ksp)->type_name);
392:     if (ksp->normtype == KSP_NORM_DEFAULT) SETERRQ2(PetscObjectComm((PetscObject)ksp),PETSC_ERR_SUP,"KSP %s does not support %s",((PetscObject)ksp)->type_name,PCSides[ksp->pc_side]);
393:     if (ksp->pc_side == PC_SIDE_DEFAULT) SETERRQ2(PetscObjectComm((PetscObject)ksp),PETSC_ERR_SUP,"KSP %s does not support %s",((PetscObject)ksp)->type_name,KSPNormTypes[ksp->normtype]);
394:     SETERRQ3(PetscObjectComm((PetscObject)ksp),PETSC_ERR_SUP,"KSP %s does not support %s with %s",((PetscObject)ksp)->type_name,KSPNormTypes[ksp->normtype],PCSides[ksp->pc_side]);
395:   }
396:   if (normtype) *normtype = (KSPNormType)ibest;
397:   if (pcside)   *pcside   = (PCSide)jbest;
398:   return(0);
399: }

401: /*@
402:    KSPGetNormType - Gets the norm that is used for convergence testing.

404:    Not Collective

406:    Input Parameter:
407: .  ksp - Krylov solver context

409:    Output Parameter:
410: .  normtype - norm that is used for convergence testing

412:    Level: advanced

414: .keywords: KSP, create, context, norms

416: .seealso: KSPNormType, KSPSetNormType(), KSPConvergedSkip()
417: @*/
418: PetscErrorCode  KSPGetNormType(KSP ksp, KSPNormType *normtype)
419: {

425:   KSPSetUpNorms_Private(ksp,PETSC_TRUE,&ksp->normtype,&ksp->pc_side);
426:   *normtype = ksp->normtype;
427:   return(0);
428: }

430: #if defined(PETSC_HAVE_SAWS)
431:  #include <petscviewersaws.h>
432: #endif

434: /*@
435:    KSPSetOperators - Sets the matrix associated with the linear system
436:    and a (possibly) different one associated with the preconditioner.

438:    Collective on KSP and Mat

440:    Input Parameters:
441: +  ksp - the KSP context
442: .  Amat - the matrix that defines the linear system
443: -  Pmat - the matrix to be used in constructing the preconditioner, usually the same as Amat.

445:    Notes:

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

450:     All future calls to KSPSetOperators() must use the same size matrices!

452:     Passing a NULL for Amat or Pmat removes the matrix that is currently used.

454:     If you wish to replace either Amat or Pmat but leave the other one untouched then
455:     first call KSPGetOperators() to get the one you wish to keep, call PetscObjectReference()
456:     on it and then pass it back in in your call to KSPSetOperators().

458:     Level: beginner

460:    Alternative usage: If the operators have NOT been set with KSP/PCSetOperators() then the operators
461:       are created in PC and returned to the user. In this case, if both operators
462:       mat and pmat are requested, two DIFFERENT operators will be returned. If
463:       only one is requested both operators in the PC will be the same (i.e. as
464:       if one had called KSP/PCSetOperators() with the same argument for both Mats).
465:       The user must set the sizes of the returned matrices and their type etc just
466:       as if the user created them with MatCreate(). For example,

468: $         KSP/PCGetOperators(ksp/pc,&mat,NULL); is equivalent to
469: $           set size, type, etc of mat

471: $         MatCreate(comm,&mat);
472: $         KSP/PCSetOperators(ksp/pc,mat,mat);
473: $         PetscObjectDereference((PetscObject)mat);
474: $           set size, type, etc of mat

476:      and

478: $         KSP/PCGetOperators(ksp/pc,&mat,&pmat); is equivalent to
479: $           set size, type, etc of mat and pmat

481: $         MatCreate(comm,&mat);
482: $         MatCreate(comm,&pmat);
483: $         KSP/PCSetOperators(ksp/pc,mat,pmat);
484: $         PetscObjectDereference((PetscObject)mat);
485: $         PetscObjectDereference((PetscObject)pmat);
486: $           set size, type, etc of mat and pmat

488:     The rational for this support is so that when creating a TS, SNES, or KSP the hierarchy
489:     of underlying objects (i.e. SNES, KSP, PC, Mat) and their livespans can be completely
490:     managed by the top most level object (i.e. the TS, SNES, or KSP). Another way to look
491:     at this is when you create a SNES you do not NEED to create a KSP and attach it to
492:     the SNES object (the SNES object manages it for you). Similarly when you create a KSP
493:     you do not need to attach a PC to it (the KSP object manages the PC object for you).
494:     Thus, why should YOU have to create the Mat and attach it to the SNES/KSP/PC, when
495:     it can be created for you?

497: .keywords: KSP, set, operators, matrix, preconditioner, linear system

499: .seealso: KSPSolve(), KSPGetPC(), PCGetOperators(), PCSetOperators(), KSPGetOperators(), KSPSetComputeOperators(), KSPSetComputeInitialGuess(), KSPSetComputeRHS()
500: @*/
501: PetscErrorCode  KSPSetOperators(KSP ksp,Mat Amat,Mat Pmat)
502: {

511:   if (!ksp->pc) {KSPGetPC(ksp,&ksp->pc);}
512:   PCSetOperators(ksp->pc,Amat,Pmat);
513:   if (ksp->setupstage == KSP_SETUP_NEWRHS) ksp->setupstage = KSP_SETUP_NEWMATRIX;  /* so that next solve call will call PCSetUp() on new matrix */
514:   return(0);
515: }

517: /*@
518:    KSPGetOperators - Gets the matrix associated with the linear system
519:    and a (possibly) different one associated with the preconditioner.

521:    Collective on KSP and Mat

523:    Input Parameter:
524: .  ksp - the KSP context

526:    Output Parameters:
527: +  Amat - the matrix that defines the linear system
528: -  Pmat - the matrix to be used in constructing the preconditioner, usually the same as Amat.

530:     Level: intermediate

532:    Notes:
533:     DOES NOT increase the reference counts of the matrix, so you should NOT destroy them.

535: .keywords: KSP, set, get, operators, matrix, preconditioner, linear system

537: .seealso: KSPSolve(), KSPGetPC(), PCGetOperators(), PCSetOperators(), KSPSetOperators(), KSPGetOperatorsSet()
538: @*/
539: PetscErrorCode  KSPGetOperators(KSP ksp,Mat *Amat,Mat *Pmat)
540: {

545:   if (!ksp->pc) {KSPGetPC(ksp,&ksp->pc);}
546:   PCGetOperators(ksp->pc,Amat,Pmat);
547:   return(0);
548: }

550: /*@C
551:    KSPGetOperatorsSet - Determines if the matrix associated with the linear system and
552:    possibly a different one associated with the preconditioner have been set in the KSP.

554:    Not collective, though the results on all processes should be the same

556:    Input Parameter:
557: .  pc - the KSP context

559:    Output Parameters:
560: +  mat - the matrix associated with the linear system was set
561: -  pmat - matrix associated with the preconditioner was set, usually the same

563:    Level: intermediate

565: .keywords: KSP, get, operators, matrix, linear system

567: .seealso: PCSetOperators(), KSPGetOperators(), KSPSetOperators(), PCGetOperators(), PCGetOperatorsSet()
568: @*/
569: PetscErrorCode  KSPGetOperatorsSet(KSP ksp,PetscBool  *mat,PetscBool  *pmat)
570: {

575:   if (!ksp->pc) {KSPGetPC(ksp,&ksp->pc);}
576:   PCGetOperatorsSet(ksp->pc,mat,pmat);
577:   return(0);
578: }

580: /*@C
581:    KSPSetPreSolve - Sets a function that is called before every KSPSolve() is started

583:    Logically Collective on KSP

585:    Input Parameters:
586: +   ksp - the solver object
587: .   presolve - the function to call before the solve
588: -   prectx - any context needed by the function

590:    Level: developer

592: .keywords: KSP, create, context

594: .seealso: KSPSetUp(), KSPSolve(), KSPDestroy(), KSP, KSPSetPostSolve()
595: @*/
596: PetscErrorCode  KSPSetPreSolve(KSP ksp,PetscErrorCode (*presolve)(KSP,Vec,Vec,void*),void *prectx)
597: {
600:   ksp->presolve = presolve;
601:   ksp->prectx   = prectx;
602:   return(0);
603: }

605: /*@C
606:    KSPSetPostSolve - Sets a function that is called after every KSPSolve() completes (whether it converges or not)

608:    Logically Collective on KSP

610:    Input Parameters:
611: +   ksp - the solver object
612: .   postsolve - the function to call after the solve
613: -   postctx - any context needed by the function

615:    Level: developer

617: .keywords: KSP, create, context

619: .seealso: KSPSetUp(), KSPSolve(), KSPDestroy(), KSP, KSPSetPreSolve()
620: @*/
621: PetscErrorCode  KSPSetPostSolve(KSP ksp,PetscErrorCode (*postsolve)(KSP,Vec,Vec,void*),void *postctx)
622: {
625:   ksp->postsolve = postsolve;
626:   ksp->postctx   = postctx;
627:   return(0);
628: }

630: /*@
631:    KSPCreate - Creates the default KSP context.

633:    Collective on MPI_Comm

635:    Input Parameter:
636: .  comm - MPI communicator

638:    Output Parameter:
639: .  ksp - location to put the KSP context

641:    Notes:
642:    The default KSP type is GMRES with a restart of 30, using modified Gram-Schmidt
643:    orthogonalization.

645:    Level: beginner

647: .keywords: KSP, create, context

649: .seealso: KSPSetUp(), KSPSolve(), KSPDestroy(), KSP
650: @*/
651: PetscErrorCode  KSPCreate(MPI_Comm comm,KSP *inksp)
652: {
653:   KSP            ksp;
655:   void           *ctx;

659:   *inksp = 0;
660:   KSPInitializePackage();

662:   PetscHeaderCreate(ksp,KSP_CLASSID,"KSP","Krylov Method","KSP",comm,KSPDestroy,KSPView);

664:   ksp->max_it  = 10000;
665:   ksp->pc_side = ksp->pc_side_set = PC_SIDE_DEFAULT;
666:   ksp->rtol    = 1.e-5;
667: #if defined(PETSC_USE_REAL_SINGLE)
668:   ksp->abstol  = 1.e-25;
669: #else
670:   ksp->abstol  = 1.e-50;
671: #endif
672:   ksp->divtol  = 1.e4;

674:   ksp->chknorm        = -1;
675:   ksp->normtype       = ksp->normtype_set = KSP_NORM_DEFAULT;
676:   ksp->rnorm          = 0.0;
677:   ksp->its            = 0;
678:   ksp->guess_zero     = PETSC_TRUE;
679:   ksp->calc_sings     = PETSC_FALSE;
680:   ksp->res_hist       = NULL;
681:   ksp->res_hist_alloc = NULL;
682:   ksp->res_hist_len   = 0;
683:   ksp->res_hist_max   = 0;
684:   ksp->res_hist_reset = PETSC_TRUE;
685:   ksp->numbermonitors = 0;
686:   ksp->setfromoptionscalled = 0;

688:   KSPConvergedDefaultCreate(&ctx);
689:   KSPSetConvergenceTest(ksp,KSPConvergedDefault,ctx,KSPConvergedDefaultDestroy);
690:   ksp->ops->buildsolution = KSPBuildSolutionDefault;
691:   ksp->ops->buildresidual = KSPBuildResidualDefault;

693:   ksp->vec_sol    = 0;
694:   ksp->vec_rhs    = 0;
695:   ksp->pc         = 0;
696:   ksp->data       = 0;
697:   ksp->nwork      = 0;
698:   ksp->work       = 0;
699:   ksp->reason     = KSP_CONVERGED_ITERATING;
700:   ksp->setupstage = KSP_SETUP_NEW;

702:   KSPNormSupportTableReset_Private(ksp);

704:   *inksp = ksp;
705:   return(0);
706: }

708: /*@C
709:    KSPSetType - Builds KSP for a particular solver.

711:    Logically Collective on KSP

713:    Input Parameters:
714: +  ksp      - the Krylov space context
715: -  type - a known method

717:    Options Database Key:
718: .  -ksp_type  <method> - Sets the method; use -help for a list
719:     of available methods (for instance, cg or gmres)

721:    Notes:
722:    See "petsc/include/petscksp.h" for available methods (for instance,
723:    KSPCG or KSPGMRES).

725:   Normally, it is best to use the KSPSetFromOptions() command and
726:   then set the KSP type from the options database rather than by using
727:   this routine.  Using the options database provides the user with
728:   maximum flexibility in evaluating the many different Krylov methods.
729:   The KSPSetType() routine is provided for those situations where it
730:   is necessary to set the iterative solver independently of the command
731:   line or options database.  This might be the case, for example, when
732:   the choice of iterative solver changes during the execution of the
733:   program, and the user's application is taking responsibility for
734:   choosing the appropriate method.  In other words, this routine is
735:   not for beginners.

737:   Level: intermediate

739:   Developer Note: KSPRegister() is used to add Krylov types to KSPList from which they
740:   are accessed by KSPSetType().

742: .keywords: KSP, set, method

744: .seealso: PCSetType(), KSPType, KSPRegister(), KSPCreate()

746: @*/
747: PetscErrorCode  KSPSetType(KSP ksp, KSPType type)
748: {
749:   PetscErrorCode ierr,(*r)(KSP);
750:   PetscBool      match;
751:   void           *ctx;


757:   PetscObjectTypeCompare((PetscObject)ksp,type,&match);
758:   if (match) return(0);

760:    PetscFunctionListFind(KSPList,type,&r);
761:   if (!r) SETERRQ1(PetscObjectComm((PetscObject)ksp),PETSC_ERR_ARG_UNKNOWN_TYPE,"Unable to find requested KSP type %s",type);
762:   /* Destroy the previous private KSP context */
763:   if (ksp->ops->destroy) {
764:     (*ksp->ops->destroy)(ksp);
765:     ksp->ops->destroy = NULL;
766:   }
767:   /* Reinitialize function pointers in KSPOps structure */
768:   PetscMemzero(ksp->ops,sizeof(struct _KSPOps));
769:   KSPConvergedDefaultCreate(&ctx);
770:   KSPSetConvergenceTest(ksp,KSPConvergedDefault,ctx,KSPConvergedDefaultDestroy);
771:   ksp->ops->buildsolution = KSPBuildSolutionDefault;
772:   ksp->ops->buildresidual = KSPBuildResidualDefault;
773:   KSPNormSupportTableReset_Private(ksp);
774:   /* Call the KSPCreate_XXX routine for this particular Krylov solver */
775:   ksp->setupstage = KSP_SETUP_NEW;
776:   PetscObjectChangeTypeName((PetscObject)ksp,type);
777:   (*r)(ksp);
778:   return(0);
779: }

781: /*@C
782:    KSPGetType - Gets the KSP type as a string from the KSP object.

784:    Not Collective

786:    Input Parameter:
787: .  ksp - Krylov context

789:    Output Parameter:
790: .  name - name of KSP method

792:    Level: intermediate

794: .keywords: KSP, get, method, name

796: .seealso: KSPSetType()
797: @*/
798: PetscErrorCode  KSPGetType(KSP ksp,KSPType *type)
799: {
803:   *type = ((PetscObject)ksp)->type_name;
804:   return(0);
805: }

807: /*@C
808:   KSPRegister -  Adds a method to the Krylov subspace solver package.

810:    Not Collective

812:    Input Parameters:
813: +  name_solver - name of a new user-defined solver
814: -  routine_create - routine to create method context

816:    Notes:
817:    KSPRegister() may be called multiple times to add several user-defined solvers.

819:    Sample usage:
820: .vb
821:    KSPRegister("my_solver",MySolverCreate);
822: .ve

824:    Then, your solver can be chosen with the procedural interface via
825: $     KSPSetType(ksp,"my_solver")
826:    or at runtime via the option
827: $     -ksp_type my_solver

829:    Level: advanced

831: .keywords: KSP, register

833: .seealso: KSPRegisterAll(), KSPRegisterDestroy()

835: @*/
836: PetscErrorCode  KSPRegister(const char sname[],PetscErrorCode (*function)(KSP))
837: {

841:   KSPInitializePackage();
842:   PetscFunctionListAdd(&KSPList,sname,function);
843:   return(0);
844: }