Actual source code: itcreate.c

petsc-3.5.0 2014-06-30
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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      isams;
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,&isams);
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:       PetscDrawBoxedString(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 (isams) {
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->pc) {KSPGetPC(ksp,&ksp->pc);}
211:   PCView(ksp->pc,viewer);
212:   if (isdraw) {
213:     PetscDraw draw;
214:     PetscViewerDrawGetDraw(viewer,0,&draw);
215:     PetscDrawPopCurrentPoint(draw);
216:   }
217:   return(0);
218: }


223: /*@
224:    KSPSetNormType - Sets the norm that is used for convergence testing.

226:    Logically Collective on KSP

228:    Input Parameter:
229: +  ksp - Krylov solver context
230: -  normtype - one of
231: $   KSP_NORM_NONE - skips computing the norm, this should only be used if you are using
232: $                 the Krylov method as a smoother with a fixed small number of iterations.
233: $                 Implicitly sets KSPConvergedSkip as KSP convergence test.
234: $                 Supported only by CG, Richardson, Bi-CG-stab, CR, and CGS methods.
235: $   KSP_NORM_PRECONDITIONED - the default for left preconditioned solves, uses the l2 norm
236: $                 of the preconditioned residual
237: $   KSP_NORM_UNPRECONDITIONED - uses the l2 norm of the true b - Ax residual, supported only by
238: $                 CG, CHEBYSHEV, and RICHARDSON, automatically true for right (see KSPSetPCSide())
239: $                 preconditioning..
240: $   KSP_NORM_NATURAL - supported  by KSPCG, KSPCR, KSPCGNE, KSPCGS


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

246:    Notes:
247:    Currently only works with the CG, Richardson, Bi-CG-stab, CR, and CGS methods.

249:    Level: advanced

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

253: .seealso: KSPSetUp(), KSPSolve(), KSPDestroy(), KSPConvergedSkip(), KSPSetCheckNormIteration()
254: @*/
255: PetscErrorCode  KSPSetNormType(KSP ksp,KSPNormType normtype)
256: {

262:   ksp->normtype = normtype;
263:   if (normtype == KSP_NORM_NONE) {
264:     KSPSetConvergenceTest(ksp,KSPConvergedSkip,0,0);
265:     PetscInfo(ksp,"Warning: setting KSPNormType to skip computing the norm\n\
266:  KSP convergence test is implicitly set to KSPConvergedSkip\n");
267:   }
268:   return(0);
269: }

273: /*@
274:    KSPSetCheckNormIteration - Sets the first iteration at which the norm of the residual will be
275:      computed and used in the convergence test.

277:    Logically Collective on KSP

279:    Input Parameter:
280: +  ksp - Krylov solver context
281: -  it  - use -1 to check at all iterations

283:    Notes:
284:    Currently only works with KSPCG, KSPBCGS and KSPIBCGS

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

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

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

294: .seealso: KSPSetUp(), KSPSolve(), KSPDestroy(), KSPConvergedSkip(), KSPSetNormType()
295: @*/
296: PetscErrorCode  KSPSetCheckNormIteration(KSP ksp,PetscInt it)
297: {
301:   ksp->chknorm = it;
302:   return(0);
303: }

307: /*@
308:    KSPSetLagNorm - Lags the residual norm calculation so that it is computed as part of the MPI_Allreduce() for
309:    computing the inner products for the next iteration.  This can reduce communication costs at the expense of doing
310:    one additional iteration.


313:    Logically Collective on KSP

315:    Input Parameter:
316: +  ksp - Krylov solver context
317: -  flg - PETSC_TRUE or PETSC_FALSE

319:    Options Database Keys:
320: .  -ksp_lag_norm - lag the calculated residual norm

322:    Notes:
323:    Currently only works with KSPIBCGS.

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

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

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

332: .seealso: KSPSetUp(), KSPSolve(), KSPDestroy(), KSPConvergedSkip(), KSPSetNormType(), KSPSetCheckNormIteration()
333: @*/
334: PetscErrorCode  KSPSetLagNorm(KSP ksp,PetscBool flg)
335: {
339:   ksp->lagnorm = flg;
340:   return(0);
341: }

345: /*@
346:    KSPSetSupportedNorm - Sets a norm and preconditioner side supported by a KSP

348:    Logically Collective

350:    Input Arguments:
351: +  ksp - Krylov method
352: .  normtype - supported norm type
353: .  pcside - preconditioner side that can be used with this norm
354: -  preference - integer preference for this combination, larger values have higher priority

356:    Level: developer

358:    Notes:
359:    This function should be called from the implementation files KSPCreate_XXX() to declare
360:    which norms and preconditioner sides are supported. Users should not need to call this
361:    function.

363:    KSP_NORM_NONE is supported by default with all KSP methods and any PC side. If a KSP explicitly does not support
364:    KSP_NORM_NONE, it should set this by setting priority=0.

366: .seealso: KSPSetNormType(), KSPSetPCSide()
367: @*/
368: PetscErrorCode KSPSetSupportedNorm(KSP ksp,KSPNormType normtype,PCSide pcside,PetscInt priority)
369: {

373:   ksp->normsupporttable[normtype][pcside] = priority;
374:   return(0);
375: }

379: PetscErrorCode KSPNormSupportTableReset_Private(KSP ksp)
380: {

384:   PetscMemzero(ksp->normsupporttable,sizeof(ksp->normsupporttable));
385:   KSPSetSupportedNorm(ksp,KSP_NORM_NONE,PC_LEFT,1);
386:   KSPSetSupportedNorm(ksp,KSP_NORM_NONE,PC_RIGHT,1);
387:   return(0);
388: }

392: PetscErrorCode KSPSetUpNorms_Private(KSP ksp,KSPNormType *normtype,PCSide *pcside)
393: {
394:   PetscInt i,j,best,ibest = 0,jbest = 0;

397:   best = 0;
398:   for (i=0; i<KSP_NORM_MAX; i++) {
399:     for (j=0; j<PC_SIDE_MAX; j++) {
400:       if ((ksp->normtype == KSP_NORM_DEFAULT || ksp->normtype == i)
401:           && (ksp->pc_side == PC_SIDE_DEFAULT || ksp->pc_side == j)
402:           && (ksp->normsupporttable[i][j] > best)) {
403:         if (ksp->normtype == KSP_NORM_DEFAULT && i == KSP_NORM_NONE && ksp->normsupporttable[i][j] <= 1) {
404:           continue; /* Skip because we don't want to default to no norms unless set by the KSP (preonly). */
405:         }
406:         best  = ksp->normsupporttable[i][j];
407:         ibest = i;
408:         jbest = j;
409:       }
410:     }
411:   }
412:   if (best < 1) {
413:     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);
414:     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]);
415:     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]);
416:     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]);
417:   }
418:   *normtype = (KSPNormType)ibest;
419:   *pcside   = (PCSide)jbest;
420:   return(0);
421: }

425: /*@
426:    KSPGetNormType - Gets the norm that is used for convergence testing.

428:    Not Collective

430:    Input Parameter:
431: .  ksp - Krylov solver context

433:    Output Parameter:
434: .  normtype - norm that is used for convergence testing

436:    Level: advanced

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

440: .seealso: KSPNormType, KSPSetNormType(), KSPConvergedSkip()
441: @*/
442: PetscErrorCode  KSPGetNormType(KSP ksp, KSPNormType *normtype)
443: {

449:   KSPSetUpNorms_Private(ksp,&ksp->normtype,&ksp->pc_side);
450:   *normtype = ksp->normtype;
451:   return(0);
452: }

454: #if defined(PETSC_HAVE_SAWS)
455: #include <petscviewersaws.h>
456: #endif

460: /*@
461:    KSPSetOperators - Sets the matrix associated with the linear system
462:    and a (possibly) different one associated with the preconditioner.

464:    Collective on KSP and Mat

466:    Input Parameters:
467: +  ksp - the KSP context
468: .  Amat - the matrix that defines the linear system
469: -  Pmat - the matrix to be used in constructing the preconditioner, usually the same as Amat.

471:    Notes:

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

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

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

481:     Level: beginner

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

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

494: $         MatCreate(comm,&mat);
495: $         KSP/PCSetOperators(ksp/pc,mat,mat);
496: $         PetscObjectDereference((PetscObject)mat);
497: $           set size, type, etc of mat

499:      and

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

504: $         MatCreate(comm,&mat);
505: $         MatCreate(comm,&pmat);
506: $         KSP/PCSetOperators(ksp/pc,mat,pmat);
507: $         PetscObjectDereference((PetscObject)mat);
508: $         PetscObjectDereference((PetscObject)pmat);
509: $           set size, type, etc of mat and pmat

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

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

522: .seealso: KSPSolve(), KSPGetPC(), PCGetOperators(), PCSetOperators(), KSPGetOperators()
523: @*/
524: PetscErrorCode  KSPSetOperators(KSP ksp,Mat Amat,Mat Pmat)
525: {
526:   MatNullSpace   nullsp;

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

552: /*@
553:    KSPGetOperators - Gets the matrix associated with the linear system
554:    and a (possibly) different one associated with the preconditioner.

556:    Collective on KSP and Mat

558:    Input Parameter:
559: .  ksp - the KSP context

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

565:     Level: intermediate

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

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

571: .seealso: KSPSolve(), KSPGetPC(), PCGetOperators(), PCSetOperators(), KSPSetOperators(), KSPGetOperatorsSet()
572: @*/
573: PetscErrorCode  KSPGetOperators(KSP ksp,Mat *Amat,Mat *Pmat)
574: {

579:   if (!ksp->pc) {KSPGetPC(ksp,&ksp->pc);}
580:   PCGetOperators(ksp->pc,Amat,Pmat);
581:   return(0);
582: }

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

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

592:    Input Parameter:
593: .  pc - the KSP context

595:    Output Parameters:
596: +  mat - the matrix associated with the linear system was set
597: -  pmat - matrix associated with the preconditioner was set, usually the same

599:    Level: intermediate

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

603: .seealso: PCSetOperators(), KSPGetOperators(), KSPSetOperators(), PCGetOperators(), PCGetOperatorsSet()
604: @*/
605: PetscErrorCode  KSPGetOperatorsSet(KSP ksp,PetscBool  *mat,PetscBool  *pmat)
606: {

611:   if (!ksp->pc) {KSPGetPC(ksp,&ksp->pc);}
612:   PCGetOperatorsSet(ksp->pc,mat,pmat);
613:   return(0);
614: }

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

621:    Logically Collective on KSP

623:    Input Parameters:
624: +   ksp - the solver object
625: .   presolve - the function to call before the solve
626: -   prectx - any context needed by the function

628:    Level: developer

630: .keywords: KSP, create, context

632: .seealso: KSPSetUp(), KSPSolve(), KSPDestroy(), KSP, KSPSetPostSolve()
633: @*/
634: PetscErrorCode  KSPSetPreSolve(KSP ksp,PetscErrorCode (*presolve)(KSP,Vec,Vec,void*),void *prectx)
635: {
638:   ksp->presolve = presolve;
639:   ksp->prectx   = prectx;
640:   return(0);
641: }

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

648:    Logically Collective on KSP

650:    Input Parameters:
651: +   ksp - the solver object
652: .   postsolve - the function to call after the solve
653: -   postctx - any context needed by the function

655:    Level: developer

657: .keywords: KSP, create, context

659: .seealso: KSPSetUp(), KSPSolve(), KSPDestroy(), KSP, KSPSetPreSolve()
660: @*/
661: PetscErrorCode  KSPSetPostSolve(KSP ksp,PetscErrorCode (*postsolve)(KSP,Vec,Vec,void*),void *postctx)
662: {
665:   ksp->postsolve = postsolve;
666:   ksp->postctx   = postctx;
667:   return(0);
668: }

672: /*@
673:    KSPCreate - Creates the default KSP context.

675:    Collective on MPI_Comm

677:    Input Parameter:
678: .  comm - MPI communicator

680:    Output Parameter:
681: .  ksp - location to put the KSP context

683:    Notes:
684:    The default KSP type is GMRES with a restart of 30, using modified Gram-Schmidt
685:    orthogonalization.

687:    Level: beginner

689: .keywords: KSP, create, context

691: .seealso: KSPSetUp(), KSPSolve(), KSPDestroy(), KSP
692: @*/
693: PetscErrorCode  KSPCreate(MPI_Comm comm,KSP *inksp)
694: {
695:   KSP            ksp;
697:   void           *ctx;

701:   *inksp = 0;
702:   KSPInitializePackage();

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

706:   ksp->max_it  = 10000;
707:   ksp->pc_side = PC_SIDE_DEFAULT;
708:   ksp->rtol    = 1.e-5;
709: #if defined(PETSC_USE_REAL_SINGLE)
710:   ksp->abstol  = 1.e-25;
711: #else
712:   ksp->abstol  = 1.e-50;
713: #endif
714:   ksp->divtol  = 1.e4;

716:   ksp->chknorm        = -1;
717:   ksp->normtype       = KSP_NORM_DEFAULT;
718:   ksp->rnorm          = 0.0;
719:   ksp->its            = 0;
720:   ksp->guess_zero     = PETSC_TRUE;
721:   ksp->calc_sings     = PETSC_FALSE;
722:   ksp->res_hist       = NULL;
723:   ksp->res_hist_alloc = NULL;
724:   ksp->res_hist_len   = 0;
725:   ksp->res_hist_max   = 0;
726:   ksp->res_hist_reset = PETSC_TRUE;
727:   ksp->numbermonitors = 0;

729:   KSPConvergedDefaultCreate(&ctx);
730:   KSPSetConvergenceTest(ksp,KSPConvergedDefault,ctx,KSPConvergedDefaultDestroy);
731:   ksp->ops->buildsolution = KSPBuildSolutionDefault;
732:   ksp->ops->buildresidual = KSPBuildResidualDefault;

734:   ksp->vec_sol    = 0;
735:   ksp->vec_rhs    = 0;
736:   ksp->pc         = 0;
737:   ksp->data       = 0;
738:   ksp->nwork      = 0;
739:   ksp->work       = 0;
740:   ksp->reason     = KSP_CONVERGED_ITERATING;
741:   ksp->setupstage = KSP_SETUP_NEW;

743:   KSPNormSupportTableReset_Private(ksp);

745:   *inksp = ksp;
746:   return(0);
747: }

751: /*@C
752:    KSPSetType - Builds KSP for a particular solver.

754:    Logically Collective on KSP

756:    Input Parameters:
757: +  ksp      - the Krylov space context
758: -  type - a known method

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

764:    Notes:
765:    See "petsc/include/petscksp.h" for available methods (for instance,
766:    KSPCG or KSPGMRES).

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

780:   Level: intermediate

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

785: .keywords: KSP, set, method

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

789: @*/
790: PetscErrorCode  KSPSetType(KSP ksp, KSPType type)
791: {
792:   PetscErrorCode ierr,(*r)(KSP);
793:   PetscBool      match;


799:   PetscObjectTypeCompare((PetscObject)ksp,type,&match);
800:   if (match) return(0);

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

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

826:    Not Collective

828:    Input Parameter:
829: .  ksp - Krylov context

831:    Output Parameter:
832: .  name - name of KSP method

834:    Level: intermediate

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

838: .seealso: KSPSetType()
839: @*/
840: PetscErrorCode  KSPGetType(KSP ksp,KSPType *type)
841: {
845:   *type = ((PetscObject)ksp)->type_name;
846:   return(0);
847: }

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

854:    Not Collective

856:    Input Parameters:
857: +  name_solver - name of a new user-defined solver
858: -  routine_create - routine to create method context

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

863:    Sample usage:
864: .vb
865:    KSPRegister("my_solver",MySolverCreate);
866: .ve

868:    Then, your solver can be chosen with the procedural interface via
869: $     KSPSetType(ksp,"my_solver")
870:    or at runtime via the option
871: $     -ksp_type my_solver

873:    Level: advanced

875: .keywords: KSP, register

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

879: @*/
880: PetscErrorCode  KSPRegister(const char sname[],PetscErrorCode (*function)(KSP))
881: {

885:   PetscFunctionListAdd(&KSPList,sname,function);
886:   return(0);
887: }

891: /*@
892:   KSPSetNullSpace - Sets the null space of the operator

894:   Logically Collective on KSP

896:   Input Parameters:
897: +  ksp - the Krylov space object
898: -  nullsp - the null space of the operator

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

903:   Level: advanced

905: .seealso: KSPSetOperators(), MatNullSpaceCreate(), KSPGetNullSpace(), MatSetNullSpace()
906: @*/
907: PetscErrorCode  KSPSetNullSpace(KSP ksp,MatNullSpace nullsp)
908: {

914:   PetscObjectReference((PetscObject)nullsp);
915:   if (ksp->nullsp) { MatNullSpaceDestroy(&ksp->nullsp); }
916:   ksp->nullsp = nullsp;
917:   return(0);
918: }

922: /*@
923:   KSPGetNullSpace - Gets the null space of the operator

925:   Not Collective

927:   Input Parameters:
928: +  ksp - the Krylov space object
929: -  nullsp - the null space of the operator

931:   Level: advanced

933: .seealso: KSPSetOperators(), MatNullSpaceCreate(), KSPSetNullSpace()
934: @*/
935: PetscErrorCode  KSPGetNullSpace(KSP ksp,MatNullSpace *nullsp)
936: {
940:   *nullsp = ksp->nullsp;
941:   return(0);
942: }