Actual source code: itcreate.c

petsc-3.11.1 2019-04-17
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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 generally 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: $                 Note that certain algorithms such as KSPGMRES ALWAYS require the norm calculation,
236: $                 for these methods the norms are still computed, they are just not used in
237: $                 the convergence test. 
238: $   KSP_NORM_PRECONDITIONED - the default for left preconditioned solves, uses the l2 norm
239: $                 of the preconditioned residual P^{-1}(b - A x)
240: $   KSP_NORM_UNPRECONDITIONED - uses the l2 norm of the true b - Ax residual.
241: $   KSP_NORM_NATURAL - supported  by KSPCG, KSPCR, KSPCGNE, KSPCGS


244:    Options Database Key:
245: .   -ksp_norm_type <none,preconditioned,unpreconditioned,natural>

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

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

255:    Level: advanced

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

259: .seealso: KSPSetUp(), KSPSolve(), KSPDestroy(), KSPConvergedSkip(), KSPSetCheckNormIteration(), KSPSetPCSide(), KSPGetPCSide(), KSPNormType
260: @*/
261: PetscErrorCode  KSPSetNormType(KSP ksp,KSPNormType normtype)
262: {
266:   ksp->normtype = ksp->normtype_set = normtype;
267:   return(0);
268: }

270: /*@
271:    KSPSetCheckNormIteration - Sets the first iteration at which the norm of the residual will be
272:      computed and used in the convergence test.

274:    Logically Collective on KSP

276:    Input Parameter:
277: +  ksp - Krylov solver context
278: -  it  - use -1 to check at all iterations

280:    Notes:
281:    Currently only works with KSPCG, KSPBCGS and KSPIBCGS

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

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

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

291: .seealso: KSPSetUp(), KSPSolve(), KSPDestroy(), KSPConvergedSkip(), KSPSetNormType()
292: @*/
293: PetscErrorCode  KSPSetCheckNormIteration(KSP ksp,PetscInt it)
294: {
298:   ksp->chknorm = it;
299:   return(0);
300: }

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


308:    Logically Collective on KSP

310:    Input Parameter:
311: +  ksp - Krylov solver context
312: -  flg - PETSC_TRUE or PETSC_FALSE

314:    Options Database Keys:
315: .  -ksp_lag_norm - lag the calculated residual norm

317:    Notes:
318:    Currently only works with KSPIBCGS.

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

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

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

327: .seealso: KSPSetUp(), KSPSolve(), KSPDestroy(), KSPConvergedSkip(), KSPSetNormType(), KSPSetCheckNormIteration()
328: @*/
329: PetscErrorCode  KSPSetLagNorm(KSP ksp,PetscBool flg)
330: {
334:   ksp->lagnorm = flg;
335:   return(0);
336: }

338: /*@
339:    KSPSetSupportedNorm - Sets a norm and preconditioner side supported by a KSP

341:    Logically Collective

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

349:    Level: developer

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

356: .seealso: KSPSetNormType(), KSPSetPCSide()
357: @*/
358: PetscErrorCode KSPSetSupportedNorm(KSP ksp,KSPNormType normtype,PCSide pcside,PetscInt priority)
359: {

363:   ksp->normsupporttable[normtype][pcside] = priority;
364:   return(0);
365: }

367: PetscErrorCode KSPNormSupportTableReset_Private(KSP ksp)
368: {

372:   PetscMemzero(ksp->normsupporttable,sizeof(ksp->normsupporttable));
373:   ksp->pc_side  = ksp->pc_side_set;
374:   ksp->normtype = ksp->normtype_set;
375:   return(0);
376: }

378: PetscErrorCode KSPSetUpNorms_Private(KSP ksp,PetscBool errorifnotsupported,KSPNormType *normtype,PCSide *pcside)
379: {
380:   PetscInt i,j,best,ibest = 0,jbest = 0;

383:   best = 0;
384:   for (i=0; i<KSP_NORM_MAX; i++) {
385:     for (j=0; j<PC_SIDE_MAX; j++) {
386:       if ((ksp->normtype == KSP_NORM_DEFAULT || ksp->normtype == i) && (ksp->pc_side == PC_SIDE_DEFAULT || ksp->pc_side == j) && (ksp->normsupporttable[i][j] > best)) {
387:         best  = ksp->normsupporttable[i][j];
388:         ibest = i;
389:         jbest = j;
390:       }
391:     }
392:   }
393:   if (best < 1 && errorifnotsupported) {
394:     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);
395:     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]);
396:     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]);
397:     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]);
398:   }
399:   if (normtype) *normtype = (KSPNormType)ibest;
400:   if (pcside)   *pcside   = (PCSide)jbest;
401:   return(0);
402: }

404: /*@
405:    KSPGetNormType - Gets the norm that is used for convergence testing.

407:    Not Collective

409:    Input Parameter:
410: .  ksp - Krylov solver context

412:    Output Parameter:
413: .  normtype - norm that is used for convergence testing

415:    Level: advanced

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

419: .seealso: KSPNormType, KSPSetNormType(), KSPConvergedSkip()
420: @*/
421: PetscErrorCode  KSPGetNormType(KSP ksp, KSPNormType *normtype)
422: {

428:   KSPSetUpNorms_Private(ksp,PETSC_TRUE,&ksp->normtype,&ksp->pc_side);
429:   *normtype = ksp->normtype;
430:   return(0);
431: }

433: #if defined(PETSC_HAVE_SAWS)
434:  #include <petscviewersaws.h>
435: #endif

437: /*@
438:    KSPSetOperators - Sets the matrix associated with the linear system
439:    and a (possibly) different one associated with the preconditioner.

441:    Collective on KSP and Mat

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

448:    Notes:

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

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

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

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

461:     Level: beginner

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

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

474: $         MatCreate(comm,&mat);
475: $         KSP/PCSetOperators(ksp/pc,mat,mat);
476: $         PetscObjectDereference((PetscObject)mat);
477: $           set size, type, etc of mat

479:      and

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

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

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

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

502: .seealso: KSPSolve(), KSPGetPC(), PCGetOperators(), PCSetOperators(), KSPGetOperators(), KSPSetComputeOperators(), KSPSetComputeInitialGuess(), KSPSetComputeRHS()
503: @*/
504: PetscErrorCode  KSPSetOperators(KSP ksp,Mat Amat,Mat Pmat)
505: {

514:   if (!ksp->pc) {KSPGetPC(ksp,&ksp->pc);}
515:   PCSetOperators(ksp->pc,Amat,Pmat);
516:   if (ksp->setupstage == KSP_SETUP_NEWRHS) ksp->setupstage = KSP_SETUP_NEWMATRIX;  /* so that next solve call will call PCSetUp() on new matrix */
517:   return(0);
518: }

520: /*@
521:    KSPGetOperators - Gets the matrix associated with the linear system
522:    and a (possibly) different one associated with the preconditioner.

524:    Collective on KSP and Mat

526:    Input Parameter:
527: .  ksp - the KSP context

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

533:     Level: intermediate

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

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

540: .seealso: KSPSolve(), KSPGetPC(), PCGetOperators(), PCSetOperators(), KSPSetOperators(), KSPGetOperatorsSet()
541: @*/
542: PetscErrorCode  KSPGetOperators(KSP ksp,Mat *Amat,Mat *Pmat)
543: {

548:   if (!ksp->pc) {KSPGetPC(ksp,&ksp->pc);}
549:   PCGetOperators(ksp->pc,Amat,Pmat);
550:   return(0);
551: }

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

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

559:    Input Parameter:
560: .  pc - the KSP context

562:    Output Parameters:
563: +  mat - the matrix associated with the linear system was set
564: -  pmat - matrix associated with the preconditioner was set, usually the same

566:    Level: intermediate

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

570: .seealso: PCSetOperators(), KSPGetOperators(), KSPSetOperators(), PCGetOperators(), PCGetOperatorsSet()
571: @*/
572: PetscErrorCode  KSPGetOperatorsSet(KSP ksp,PetscBool  *mat,PetscBool  *pmat)
573: {

578:   if (!ksp->pc) {KSPGetPC(ksp,&ksp->pc);}
579:   PCGetOperatorsSet(ksp->pc,mat,pmat);
580:   return(0);
581: }

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

586:    Logically Collective on KSP

588:    Input Parameters:
589: +   ksp - the solver object
590: .   presolve - the function to call before the solve
591: -   prectx - any context needed by the function

593:    Calling sequence of presolve:
594: $  func(KSP ksp,Vec rhs,Vec x,void *ctx)

596: +  ksp - the KSP context
597: .  rhs - the right-hand side vector
598: .  x - the solution vector
599: -  ctx - optional user-provided context

601:    Level: developer

603: .keywords: KSP, create, context

605: .seealso: KSPSetUp(), KSPSolve(), KSPDestroy(), KSP, KSPSetPostSolve()
606: @*/
607: PetscErrorCode  KSPSetPreSolve(KSP ksp,PetscErrorCode (*presolve)(KSP,Vec,Vec,void*),void *prectx)
608: {
611:   ksp->presolve = presolve;
612:   ksp->prectx   = prectx;
613:   return(0);
614: }

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

619:    Logically Collective on KSP

621:    Input Parameters:
622: +   ksp - the solver object
623: .   postsolve - the function to call after the solve
624: -   postctx - any context needed by the function

626:    Level: developer

628:    Calling sequence of postsolve:
629: $  func(KSP ksp,Vec rhs,Vec x,void *ctx)

631: +  ksp - the KSP context
632: .  rhs - the right-hand side vector
633: .  x - the solution vector
634: -  ctx - optional user-provided context

636: .keywords: KSP, create, context

638: .seealso: KSPSetUp(), KSPSolve(), KSPDestroy(), KSP, KSPSetPreSolve()
639: @*/
640: PetscErrorCode  KSPSetPostSolve(KSP ksp,PetscErrorCode (*postsolve)(KSP,Vec,Vec,void*),void *postctx)
641: {
644:   ksp->postsolve = postsolve;
645:   ksp->postctx   = postctx;
646:   return(0);
647: }

649: /*@
650:    KSPCreate - Creates the default KSP context.

652:    Collective on MPI_Comm

654:    Input Parameter:
655: .  comm - MPI communicator

657:    Output Parameter:
658: .  ksp - location to put the KSP context

660:    Notes:
661:    The default KSP type is GMRES with a restart of 30, using modified Gram-Schmidt
662:    orthogonalization.

664:    Level: beginner

666: .keywords: KSP, create, context

668: .seealso: KSPSetUp(), KSPSolve(), KSPDestroy(), KSP
669: @*/
670: PetscErrorCode  KSPCreate(MPI_Comm comm,KSP *inksp)
671: {
672:   KSP            ksp;
674:   void           *ctx;

678:   *inksp = 0;
679:   KSPInitializePackage();

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

683:   ksp->max_it  = 10000;
684:   ksp->pc_side = ksp->pc_side_set = PC_SIDE_DEFAULT;
685:   ksp->rtol    = 1.e-5;
686: #if defined(PETSC_USE_REAL_SINGLE)
687:   ksp->abstol  = 1.e-25;
688: #else
689:   ksp->abstol  = 1.e-50;
690: #endif
691:   ksp->divtol  = 1.e4;

693:   ksp->chknorm        = -1;
694:   ksp->normtype       = ksp->normtype_set = KSP_NORM_DEFAULT;
695:   ksp->rnorm          = 0.0;
696:   ksp->its            = 0;
697:   ksp->guess_zero     = PETSC_TRUE;
698:   ksp->calc_sings     = PETSC_FALSE;
699:   ksp->res_hist       = NULL;
700:   ksp->res_hist_alloc = NULL;
701:   ksp->res_hist_len   = 0;
702:   ksp->res_hist_max   = 0;
703:   ksp->res_hist_reset = PETSC_TRUE;
704:   ksp->numbermonitors = 0;
705:   ksp->setfromoptionscalled = 0;

707:   KSPConvergedDefaultCreate(&ctx);
708:   KSPSetConvergenceTest(ksp,KSPConvergedDefault,ctx,KSPConvergedDefaultDestroy);
709:   ksp->ops->buildsolution = KSPBuildSolutionDefault;
710:   ksp->ops->buildresidual = KSPBuildResidualDefault;

712:   ksp->vec_sol    = 0;
713:   ksp->vec_rhs    = 0;
714:   ksp->pc         = 0;
715:   ksp->data       = 0;
716:   ksp->nwork      = 0;
717:   ksp->work       = 0;
718:   ksp->reason     = KSP_CONVERGED_ITERATING;
719:   ksp->setupstage = KSP_SETUP_NEW;

721:   KSPNormSupportTableReset_Private(ksp);

723:   *inksp = ksp;
724:   return(0);
725: }

727: /*@C
728:    KSPSetType - Builds KSP for a particular solver.

730:    Logically Collective on KSP

732:    Input Parameters:
733: +  ksp      - the Krylov space context
734: -  type - a known method

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

740:    Notes:
741:    See "petsc/include/petscksp.h" for available methods (for instance,
742:    KSPCG or KSPGMRES).

744:   Normally, it is best to use the KSPSetFromOptions() command and
745:   then set the KSP type from the options database rather than by using
746:   this routine.  Using the options database provides the user with
747:   maximum flexibility in evaluating the many different Krylov methods.
748:   The KSPSetType() routine is provided for those situations where it
749:   is necessary to set the iterative solver independently of the command
750:   line or options database.  This might be the case, for example, when
751:   the choice of iterative solver changes during the execution of the
752:   program, and the user's application is taking responsibility for
753:   choosing the appropriate method.  In other words, this routine is
754:   not for beginners.

756:   Level: intermediate

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

761: .keywords: KSP, set, method

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

765: @*/
766: PetscErrorCode  KSPSetType(KSP ksp, KSPType type)
767: {
768:   PetscErrorCode ierr,(*r)(KSP);
769:   PetscBool      match;
770:   void           *ctx;


776:   PetscObjectTypeCompare((PetscObject)ksp,type,&match);
777:   if (match) return(0);

779:    PetscFunctionListFind(KSPList,type,&r);
780:   if (!r) SETERRQ1(PetscObjectComm((PetscObject)ksp),PETSC_ERR_ARG_UNKNOWN_TYPE,"Unable to find requested KSP type %s",type);
781:   /* Destroy the previous private KSP context */
782:   if (ksp->ops->destroy) {
783:     (*ksp->ops->destroy)(ksp);
784:     ksp->ops->destroy = NULL;
785:   }
786:   /* Reinitialize function pointers in KSPOps structure */
787:   PetscMemzero(ksp->ops,sizeof(struct _KSPOps));
788:   KSPConvergedDefaultCreate(&ctx);
789:   KSPSetConvergenceTest(ksp,KSPConvergedDefault,ctx,KSPConvergedDefaultDestroy);
790:   ksp->ops->buildsolution = KSPBuildSolutionDefault;
791:   ksp->ops->buildresidual = KSPBuildResidualDefault;
792:   KSPNormSupportTableReset_Private(ksp);
793:   /* Call the KSPCreate_XXX routine for this particular Krylov solver */
794:   ksp->setupstage = KSP_SETUP_NEW;
795:   PetscObjectChangeTypeName((PetscObject)ksp,type);
796:   (*r)(ksp);
797:   return(0);
798: }

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

803:    Not Collective

805:    Input Parameter:
806: .  ksp - Krylov context

808:    Output Parameter:
809: .  name - name of KSP method

811:    Level: intermediate

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

815: .seealso: KSPSetType()
816: @*/
817: PetscErrorCode  KSPGetType(KSP ksp,KSPType *type)
818: {
822:   *type = ((PetscObject)ksp)->type_name;
823:   return(0);
824: }

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

829:    Not Collective

831:    Input Parameters:
832: +  name_solver - name of a new user-defined solver
833: -  routine_create - routine to create method context

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

838:    Sample usage:
839: .vb
840:    KSPRegister("my_solver",MySolverCreate);
841: .ve

843:    Then, your solver can be chosen with the procedural interface via
844: $     KSPSetType(ksp,"my_solver")
845:    or at runtime via the option
846: $     -ksp_type my_solver

848:    Level: advanced

850: .keywords: KSP, register

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

854: @*/
855: PetscErrorCode  KSPRegister(const char sname[],PetscErrorCode (*function)(KSP))
856: {

860:   KSPInitializePackage();
861:   PetscFunctionListAdd(&KSPList,sname,function);
862:   return(0);
863: }