Actual source code: itcreate.c

petsc-master 2015-03-29
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  2: /*
  3:      The basic KSP routines, Create, View etc. are here.
  4: */
  5: #include <petsc-private/kspimpl.h>      /*I "petscksp.h" I*/

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

 12: /*
 13:    Contains the list of registered KSP routines
 14: */
 15: PetscFunctionList KSPList              = 0;
 16: PetscBool         KSPRegisterAllCalled = PETSC_FALSE;

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

 23:   Collective on PetscViewer

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

 30:    Level: intermediate

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

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

 44: .seealso: PetscViewerBinaryOpen(), KSPView(), MatLoad(), VecLoad()
 45: @*/
 46: PetscErrorCode  KSPLoad(KSP newdm, PetscViewer viewer)
 47: {
 49:   PetscBool      isbinary;
 50:   PetscInt       classid;
 51:   char           type[256];
 52:   PC             pc;

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

 60:   PetscViewerBinaryRead(viewer,&classid,1,PETSC_INT);
 61:   if (classid != KSP_FILE_CLASSID) SETERRQ(PetscObjectComm((PetscObject)newdm),PETSC_ERR_ARG_WRONG,"Not KSP next in file");
 62:   PetscViewerBinaryRead(viewer,type,256,PETSC_CHAR);
 63:   KSPSetType(newdm, type);
 64:   if (newdm->ops->load) {
 65:     (*newdm->ops->load)(newdm,viewer);
 66:   }
 67:   KSPGetPC(newdm,&pc);
 68:   PCLoad(pc,viewer);
 69:   return(0);
 70: }

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

 81:    Collective on KSP

 83:    Input Parameters:
 84: +  ksp - the Krylov space context
 85: -  viewer - visualization context

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

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

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

101:    Level: beginner

103: .keywords: KSP, view

105: .seealso: PCView(), PetscViewerASCIIOpen()
106: @*/
107: PetscErrorCode  KSPView(KSP ksp,PetscViewer viewer)
108: {
110:   PetscBool      iascii,isbinary,isdraw;
111: #if defined(PETSC_HAVE_SAWS)
112:   PetscBool      issaws;
113: #endif

117:   if (!viewer) viewer = PETSC_VIEWER_STDOUT_(PetscObjectComm((PetscObject)ksp));

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

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

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

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

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


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

228:    Logically Collective on KSP

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


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

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

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


254:    Level: advanced

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

258: .seealso: KSPSetUp(), KSPSolve(), KSPDestroy(), KSPConvergedSkip(), KSPSetCheckNormIteration(), KSPSetPCSide(), KSPGetPCSide()
259: @*/
260: PetscErrorCode  KSPSetNormType(KSP ksp,KSPNormType normtype)
261: {

267:   ksp->normtype = ksp->normtype_set = normtype;
268:   if (normtype == KSP_NORM_NONE) {
269:     KSPSetConvergenceTest(ksp,KSPConvergedSkip,0,0);
270:     PetscInfo(ksp,"Warning: setting KSPNormType to skip computing the norm\n\
271:  KSP convergence test is implicitly set to KSPConvergedSkip\n");
272:   }
273:   return(0);
274: }

278: /*@
279:    KSPSetCheckNormIteration - Sets the first iteration at which the norm of the residual will be
280:      computed and used in the convergence test.

282:    Logically Collective on KSP

284:    Input Parameter:
285: +  ksp - Krylov solver context
286: -  it  - use -1 to check at all iterations

288:    Notes:
289:    Currently only works with KSPCG, KSPBCGS and KSPIBCGS

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

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

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

299: .seealso: KSPSetUp(), KSPSolve(), KSPDestroy(), KSPConvergedSkip(), KSPSetNormType()
300: @*/
301: PetscErrorCode  KSPSetCheckNormIteration(KSP ksp,PetscInt it)
302: {
306:   ksp->chknorm = it;
307:   return(0);
308: }

312: /*@
313:    KSPSetLagNorm - Lags the residual norm calculation so that it is computed as part of the MPI_Allreduce() for
314:    computing the inner products for the next iteration.  This can reduce communication costs at the expense of doing
315:    one additional iteration.


318:    Logically Collective on KSP

320:    Input Parameter:
321: +  ksp - Krylov solver context
322: -  flg - PETSC_TRUE or PETSC_FALSE

324:    Options Database Keys:
325: .  -ksp_lag_norm - lag the calculated residual norm

327:    Notes:
328:    Currently only works with KSPIBCGS.

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

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

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

337: .seealso: KSPSetUp(), KSPSolve(), KSPDestroy(), KSPConvergedSkip(), KSPSetNormType(), KSPSetCheckNormIteration()
338: @*/
339: PetscErrorCode  KSPSetLagNorm(KSP ksp,PetscBool flg)
340: {
344:   ksp->lagnorm = flg;
345:   return(0);
346: }

350: /*@
351:    KSPSetSupportedNorm - Sets a norm and preconditioner side supported by a KSP

353:    Logically Collective

355:    Input Arguments:
356: +  ksp - Krylov method
357: .  normtype - supported norm type
358: .  pcside - preconditioner side that can be used with this norm
359: -  preference - integer preference for this combination, larger values have higher priority

361:    Level: developer

363:    Notes:
364:    This function should be called from the implementation files KSPCreate_XXX() to declare
365:    which norms and preconditioner sides are supported. Users should not need to call this
366:    function.

368:    KSP_NORM_NONE is supported by default with all KSP methods and any PC side at priority 1.  If a KSP explicitly does
369:    not support KSP_NORM_NONE, it should set this by setting priority=0.  Since defaulting to KSP_NORM_NONE is usually
370:    undesirable, more desirable norms should usually have priority 2 or higher.

372: .seealso: KSPSetNormType(), KSPSetPCSide()
373: @*/
374: PetscErrorCode KSPSetSupportedNorm(KSP ksp,KSPNormType normtype,PCSide pcside,PetscInt priority)
375: {

379:   ksp->normsupporttable[normtype][pcside] = priority;
380:   return(0);
381: }

385: PetscErrorCode KSPNormSupportTableReset_Private(KSP ksp)
386: {

390:   PetscMemzero(ksp->normsupporttable,sizeof(ksp->normsupporttable));
391:   KSPSetSupportedNorm(ksp,KSP_NORM_NONE,PC_LEFT,1);
392:   KSPSetSupportedNorm(ksp,KSP_NORM_NONE,PC_RIGHT,1);
393:   ksp->pc_side  = ksp->pc_side_set;
394:   ksp->normtype = ksp->normtype_set;
395:   return(0);
396: }

400: PetscErrorCode KSPSetUpNorms_Private(KSP ksp,KSPNormType *normtype,PCSide *pcside)
401: {
402:   PetscInt i,j,best,ibest = 0,jbest = 0;

405:   best = 0;
406:   for (i=0; i<KSP_NORM_MAX; i++) {
407:     for (j=0; j<PC_SIDE_MAX; j++) {
408:       if ((ksp->normtype == KSP_NORM_DEFAULT || ksp->normtype == i)
409:           && (ksp->pc_side == PC_SIDE_DEFAULT || ksp->pc_side == j)
410:           && (ksp->normsupporttable[i][j] > best)) {
411:         best  = ksp->normsupporttable[i][j];
412:         ibest = i;
413:         jbest = j;
414:       }
415:     }
416:   }
417:   if (best < 1) {
418:     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);
419:     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]);
420:     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]);
421:     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]);
422:   }
423:   *normtype = (KSPNormType)ibest;
424:   *pcside   = (PCSide)jbest;
425:   return(0);
426: }

430: /*@
431:    KSPGetNormType - Gets the norm that is used for convergence testing.

433:    Not Collective

435:    Input Parameter:
436: .  ksp - Krylov solver context

438:    Output Parameter:
439: .  normtype - norm that is used for convergence testing

441:    Level: advanced

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

445: .seealso: KSPNormType, KSPSetNormType(), KSPConvergedSkip()
446: @*/
447: PetscErrorCode  KSPGetNormType(KSP ksp, KSPNormType *normtype)
448: {

454:   KSPSetUpNorms_Private(ksp,&ksp->normtype,&ksp->pc_side);
455:   *normtype = ksp->normtype;
456:   return(0);
457: }

459: #if defined(PETSC_HAVE_SAWS)
460: #include <petscviewersaws.h>
461: #endif

465: /*@
466:    KSPSetOperators - Sets the matrix associated with the linear system
467:    and a (possibly) different one associated with the preconditioner.

469:    Collective on KSP and Mat

471:    Input Parameters:
472: +  ksp - the KSP context
473: .  Amat - the matrix that defines the linear system
474: -  Pmat - the matrix to be used in constructing the preconditioner, usually the same as Amat.

476:    Notes:

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

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

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

486:     Level: beginner

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

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

499: $         MatCreate(comm,&mat);
500: $         KSP/PCSetOperators(ksp/pc,mat,mat);
501: $         PetscObjectDereference((PetscObject)mat);
502: $           set size, type, etc of mat

504:      and

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

509: $         MatCreate(comm,&mat);
510: $         MatCreate(comm,&pmat);
511: $         KSP/PCSetOperators(ksp/pc,mat,pmat);
512: $         PetscObjectDereference((PetscObject)mat);
513: $         PetscObjectDereference((PetscObject)pmat);
514: $           set size, type, etc of mat and pmat

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

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

527: .seealso: KSPSolve(), KSPGetPC(), PCGetOperators(), PCSetOperators(), KSPGetOperators(), KSPSetComputeOperators(), KSPSetComputeInitialGuess(), KSPSetComputeRHS()
528: @*/
529: PetscErrorCode  KSPSetOperators(KSP ksp,Mat Amat,Mat Pmat)
530: {
531:   MatNullSpace   nullsp;

540:   if (!ksp->pc) {KSPGetPC(ksp,&ksp->pc);}
541:   PCSetOperators(ksp->pc,Amat,Pmat);
542:   if (ksp->setupstage == KSP_SETUP_NEWRHS) ksp->setupstage = KSP_SETUP_NEWMATRIX;  /* so that next solve call will call PCSetUp() on new matrix */
543:   if (ksp->guess) {
544:     KSPFischerGuessReset(ksp->guess);
545:   }
546:   if (Pmat) {
547:     MatGetNullSpace(Pmat, &nullsp);
548:     if (nullsp) {
549:       KSPSetNullSpace(ksp, nullsp);
550:     }
551:   }
552:   return(0);
553: }

557: /*@
558:    KSPGetOperators - Gets the matrix associated with the linear system
559:    and a (possibly) different one associated with the preconditioner.

561:    Collective on KSP and Mat

563:    Input Parameter:
564: .  ksp - the KSP context

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

570:     Level: intermediate

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

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

576: .seealso: KSPSolve(), KSPGetPC(), PCGetOperators(), PCSetOperators(), KSPSetOperators(), KSPGetOperatorsSet()
577: @*/
578: PetscErrorCode  KSPGetOperators(KSP ksp,Mat *Amat,Mat *Pmat)
579: {

584:   if (!ksp->pc) {KSPGetPC(ksp,&ksp->pc);}
585:   PCGetOperators(ksp->pc,Amat,Pmat);
586:   return(0);
587: }

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

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

597:    Input Parameter:
598: .  pc - the KSP context

600:    Output Parameters:
601: +  mat - the matrix associated with the linear system was set
602: -  pmat - matrix associated with the preconditioner was set, usually the same

604:    Level: intermediate

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

608: .seealso: PCSetOperators(), KSPGetOperators(), KSPSetOperators(), PCGetOperators(), PCGetOperatorsSet()
609: @*/
610: PetscErrorCode  KSPGetOperatorsSet(KSP ksp,PetscBool  *mat,PetscBool  *pmat)
611: {

616:   if (!ksp->pc) {KSPGetPC(ksp,&ksp->pc);}
617:   PCGetOperatorsSet(ksp->pc,mat,pmat);
618:   return(0);
619: }

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

626:    Logically Collective on KSP

628:    Input Parameters:
629: +   ksp - the solver object
630: .   presolve - the function to call before the solve
631: -   prectx - any context needed by the function

633:    Level: developer

635: .keywords: KSP, create, context

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

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

653:    Logically Collective on KSP

655:    Input Parameters:
656: +   ksp - the solver object
657: .   postsolve - the function to call after the solve
658: -   postctx - any context needed by the function

660:    Level: developer

662: .keywords: KSP, create, context

664: .seealso: KSPSetUp(), KSPSolve(), KSPDestroy(), KSP, KSPSetPreSolve()
665: @*/
666: PetscErrorCode  KSPSetPostSolve(KSP ksp,PetscErrorCode (*postsolve)(KSP,Vec,Vec,void*),void *postctx)
667: {
670:   ksp->postsolve = postsolve;
671:   ksp->postctx   = postctx;
672:   return(0);
673: }

677: /*@
678:    KSPCreate - Creates the default KSP context.

680:    Collective on MPI_Comm

682:    Input Parameter:
683: .  comm - MPI communicator

685:    Output Parameter:
686: .  ksp - location to put the KSP context

688:    Notes:
689:    The default KSP type is GMRES with a restart of 30, using modified Gram-Schmidt
690:    orthogonalization.

692:    Level: beginner

694: .keywords: KSP, create, context

696: .seealso: KSPSetUp(), KSPSolve(), KSPDestroy(), KSP
697: @*/
698: PetscErrorCode  KSPCreate(MPI_Comm comm,KSP *inksp)
699: {
700:   KSP            ksp;
702:   void           *ctx;

706:   *inksp = 0;
707:   KSPInitializePackage();

709:   PetscHeaderCreate(ksp,_p_KSP,struct _KSPOps,KSP_CLASSID,"KSP","Krylov Method","KSP",comm,KSPDestroy,KSPView);

711:   ksp->max_it  = 10000;
712:   ksp->pc_side = ksp->pc_side_set = PC_SIDE_DEFAULT;
713:   ksp->rtol    = 1.e-5;
714: #if defined(PETSC_USE_REAL_SINGLE)
715:   ksp->abstol  = 1.e-25;
716: #else
717:   ksp->abstol  = 1.e-50;
718: #endif
719:   ksp->divtol  = 1.e4;

721:   ksp->chknorm        = -1;
722:   ksp->normtype       = ksp->normtype_set = KSP_NORM_DEFAULT;
723:   ksp->rnorm          = 0.0;
724:   ksp->its            = 0;
725:   ksp->guess_zero     = PETSC_TRUE;
726:   ksp->calc_sings     = PETSC_FALSE;
727:   ksp->res_hist       = NULL;
728:   ksp->res_hist_alloc = NULL;
729:   ksp->res_hist_len   = 0;
730:   ksp->res_hist_max   = 0;
731:   ksp->res_hist_reset = PETSC_TRUE;
732:   ksp->numbermonitors = 0;

734:   KSPConvergedDefaultCreate(&ctx);
735:   KSPSetConvergenceTest(ksp,KSPConvergedDefault,ctx,KSPConvergedDefaultDestroy);
736:   ksp->ops->buildsolution = KSPBuildSolutionDefault;
737:   ksp->ops->buildresidual = KSPBuildResidualDefault;

739:   ksp->vec_sol    = 0;
740:   ksp->vec_rhs    = 0;
741:   ksp->pc         = 0;
742:   ksp->data       = 0;
743:   ksp->nwork      = 0;
744:   ksp->work       = 0;
745:   ksp->reason     = KSP_CONVERGED_ITERATING;
746:   ksp->setupstage = KSP_SETUP_NEW;

748:   KSPNormSupportTableReset_Private(ksp);

750:   *inksp = ksp;
751:   return(0);
752: }

756: /*@C
757:    KSPSetType - Builds KSP for a particular solver.

759:    Logically Collective on KSP

761:    Input Parameters:
762: +  ksp      - the Krylov space context
763: -  type - a known method

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

769:    Notes:
770:    See "petsc/include/petscksp.h" for available methods (for instance,
771:    KSPCG or KSPGMRES).

773:   Normally, it is best to use the KSPSetFromOptions() command and
774:   then set the KSP type from the options database rather than by using
775:   this routine.  Using the options database provides the user with
776:   maximum flexibility in evaluating the many different Krylov methods.
777:   The KSPSetType() routine is provided for those situations where it
778:   is necessary to set the iterative solver independently of the command
779:   line or options database.  This might be the case, for example, when
780:   the choice of iterative solver changes during the execution of the
781:   program, and the user's application is taking responsibility for
782:   choosing the appropriate method.  In other words, this routine is
783:   not for beginners.

785:   Level: intermediate

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

790: .keywords: KSP, set, method

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

794: @*/
795: PetscErrorCode  KSPSetType(KSP ksp, KSPType type)
796: {
797:   PetscErrorCode ierr,(*r)(KSP);
798:   PetscBool      match;


804:   PetscObjectTypeCompare((PetscObject)ksp,type,&match);
805:   if (match) return(0);

807:    PetscFunctionListFind(KSPList,type,&r);
808:   if (!r) SETERRQ1(PetscObjectComm((PetscObject)ksp),PETSC_ERR_ARG_UNKNOWN_TYPE,"Unable to find requested KSP type %s",type);
809:   /* Destroy the previous private KSP context */
810:   if (ksp->ops->destroy) {
811:     (*ksp->ops->destroy)(ksp);
812:     ksp->ops->destroy = NULL;
813:   }
814:   /* Reinitialize function pointers in KSPOps structure */
815:   PetscMemzero(ksp->ops,sizeof(struct _KSPOps));
816:   ksp->ops->buildsolution = KSPBuildSolutionDefault;
817:   ksp->ops->buildresidual = KSPBuildResidualDefault;
818:   KSPNormSupportTableReset_Private(ksp);
819:   /* Call the KSPCreate_XXX routine for this particular Krylov solver */
820:   ksp->setupstage = KSP_SETUP_NEW;
821:   PetscObjectChangeTypeName((PetscObject)ksp,type);
822:   (*r)(ksp);
823:   return(0);
824: }

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

831:    Not Collective

833:    Input Parameter:
834: .  ksp - Krylov context

836:    Output Parameter:
837: .  name - name of KSP method

839:    Level: intermediate

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

843: .seealso: KSPSetType()
844: @*/
845: PetscErrorCode  KSPGetType(KSP ksp,KSPType *type)
846: {
850:   *type = ((PetscObject)ksp)->type_name;
851:   return(0);
852: }

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

859:    Not Collective

861:    Input Parameters:
862: +  name_solver - name of a new user-defined solver
863: -  routine_create - routine to create method context

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

868:    Sample usage:
869: .vb
870:    KSPRegister("my_solver",MySolverCreate);
871: .ve

873:    Then, your solver can be chosen with the procedural interface via
874: $     KSPSetType(ksp,"my_solver")
875:    or at runtime via the option
876: $     -ksp_type my_solver

878:    Level: advanced

880: .keywords: KSP, register

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

884: @*/
885: PetscErrorCode  KSPRegister(const char sname[],PetscErrorCode (*function)(KSP))
886: {

890:   PetscFunctionListAdd(&KSPList,sname,function);
891:   return(0);
892: }

896: /*@
897:   KSPSetNullSpace - Sets the null space of the operator

899:   Logically Collective on KSP

901:   Input Parameters:
902: +  ksp - the Krylov space object
903: -  nullsp - the null space of the operator

905:   Notes: If the Mat provided to KSP has a nullspace added to it with MatSetNullSpace() then
906:          KSP will automatically use the MatNullSpace and you don't need to call KSPSetNullSpace().

908:   Level: advanced

910: .seealso: KSPSetOperators(), MatNullSpaceCreate(), KSPGetNullSpace(), MatSetNullSpace()
911: @*/
912: PetscErrorCode  KSPSetNullSpace(KSP ksp,MatNullSpace nullsp)
913: {

919:   PetscObjectReference((PetscObject)nullsp);
920:   if (ksp->nullsp) { MatNullSpaceDestroy(&ksp->nullsp); }
921:   ksp->nullsp = nullsp;
922:   return(0);
923: }

927: /*@
928:   KSPGetNullSpace - Gets the null space of the operator

930:   Not Collective

932:   Input Parameters:
933: +  ksp - the Krylov space object
934: -  nullsp - the null space of the operator

936:   Level: advanced

938: .seealso: KSPSetOperators(), MatNullSpaceCreate(), KSPSetNullSpace()
939: @*/
940: PetscErrorCode  KSPGetNullSpace(KSP ksp,MatNullSpace *nullsp)
941: {
945:   *nullsp = ksp->nullsp;
946:   return(0);
947: }