Actual source code: precon.c

petsc-master 2020-10-26
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  2: /*
  3:     The PC (preconditioner) interface routines, callable by users.
  4: */
  5: #include <petsc/private/pcimpl.h>
  6: #include <petscdm.h>

  8: /* Logging support */
  9: PetscClassId  PC_CLASSID;
 10: PetscLogEvent PC_SetUp, PC_SetUpOnBlocks, PC_Apply, PC_MatApply, PC_ApplyCoarse, PC_ApplyMultiple, PC_ApplySymmetricLeft;
 11: PetscLogEvent PC_ApplySymmetricRight, PC_ModifySubMatrices, PC_ApplyOnBlocks, PC_ApplyTransposeOnBlocks;
 12: PetscInt      PetscMGLevelId;

 14: PetscErrorCode PCGetDefaultType_Private(PC pc,const char *type[])
 15: {
 17:   PetscMPIInt    size;
 18:   PetscBool      hasop,flg1,flg2,set,flg3;

 21:   MPI_Comm_size(PetscObjectComm((PetscObject)pc),&size);
 22:   if (pc->pmat) {
 23:     MatHasOperation(pc->pmat,MATOP_GET_DIAGONAL_BLOCK,&hasop);
 24:     if (size == 1) {
 25:       MatGetFactorAvailable(pc->pmat,"petsc",MAT_FACTOR_ICC,&flg1);
 26:       MatGetFactorAvailable(pc->pmat,"petsc",MAT_FACTOR_ILU,&flg2);
 27:       MatIsSymmetricKnown(pc->pmat,&set,&flg3);
 28:       if (flg1 && (!flg2 || (set && flg3))) {
 29:         *type = PCICC;
 30:       } else if (flg2) {
 31:         *type = PCILU;
 32:       } else if (hasop) { /* likely is a parallel matrix run on one processor */
 33:         *type = PCBJACOBI;
 34:       } else {
 35:         *type = PCNONE;
 36:       }
 37:     } else {
 38:        if (hasop) {
 39:         *type = PCBJACOBI;
 40:       } else {
 41:         *type = PCNONE;
 42:       }
 43:     }
 44:   } else {
 45:     if (size == 1) {
 46:       *type = PCILU;
 47:     } else {
 48:       *type = PCBJACOBI;
 49:     }
 50:   }
 51:   return(0);
 52: }

 54: /*@
 55:    PCReset - Resets a PC context to the pcsetupcalled = 0 state and removes any allocated Vecs and Mats

 57:    Collective on PC

 59:    Input Parameter:
 60: .  pc - the preconditioner context

 62:    Level: developer

 64:    Notes:
 65:     This allows a PC to be reused for a different sized linear system but using the same options that have been previously set in the PC

 67: .seealso: PCCreate(), PCSetUp()
 68: @*/
 69: PetscErrorCode  PCReset(PC pc)
 70: {

 75:   if (pc->ops->reset) {
 76:     (*pc->ops->reset)(pc);
 77:   }
 78:   VecDestroy(&pc->diagonalscaleright);
 79:   VecDestroy(&pc->diagonalscaleleft);
 80:   MatDestroy(&pc->pmat);
 81:   MatDestroy(&pc->mat);

 83:   pc->setupcalled = 0;
 84:   return(0);
 85: }

 87: /*@
 88:    PCDestroy - Destroys PC context that was created with PCCreate().

 90:    Collective on PC

 92:    Input Parameter:
 93: .  pc - the preconditioner context

 95:    Level: developer

 97: .seealso: PCCreate(), PCSetUp()
 98: @*/
 99: PetscErrorCode  PCDestroy(PC *pc)
100: {

104:   if (!*pc) return(0);
106:   if (--((PetscObject)(*pc))->refct > 0) {*pc = NULL; return(0);}

108:   PCReset(*pc);

110:   /* if memory was published with SAWs then destroy it */
111:   PetscObjectSAWsViewOff((PetscObject)*pc);
112:   if ((*pc)->ops->destroy) {(*(*pc)->ops->destroy)((*pc));}
113:   DMDestroy(&(*pc)->dm);
114:   PetscHeaderDestroy(pc);
115:   return(0);
116: }

118: /*@C
119:    PCGetDiagonalScale - Indicates if the preconditioner applies an additional left and right
120:       scaling as needed by certain time-stepping codes.

122:    Logically Collective on PC

124:    Input Parameter:
125: .  pc - the preconditioner context

127:    Output Parameter:
128: .  flag - PETSC_TRUE if it applies the scaling

130:    Level: developer

132:    Notes:
133:     If this returns PETSC_TRUE then the system solved via the Krylov method is
134: $           D M A D^{-1} y = D M b  for left preconditioning or
135: $           D A M D^{-1} z = D b for right preconditioning

137: .seealso: PCCreate(), PCSetUp(), PCDiagonalScaleLeft(), PCDiagonalScaleRight(), PCSetDiagonalScale()
138: @*/
139: PetscErrorCode  PCGetDiagonalScale(PC pc,PetscBool  *flag)
140: {
144:   *flag = pc->diagonalscale;
145:   return(0);
146: }

148: /*@
149:    PCSetDiagonalScale - Indicates the left scaling to use to apply an additional left and right
150:       scaling as needed by certain time-stepping codes.

152:    Logically Collective on PC

154:    Input Parameters:
155: +  pc - the preconditioner context
156: -  s - scaling vector

158:    Level: intermediate

160:    Notes:
161:     The system solved via the Krylov method is
162: $           D M A D^{-1} y = D M b  for left preconditioning or
163: $           D A M D^{-1} z = D b for right preconditioning

165:    PCDiagonalScaleLeft() scales a vector by D. PCDiagonalScaleRight() scales a vector by D^{-1}.

167: .seealso: PCCreate(), PCSetUp(), PCDiagonalScaleLeft(), PCDiagonalScaleRight(), PCGetDiagonalScale()
168: @*/
169: PetscErrorCode  PCSetDiagonalScale(PC pc,Vec s)
170: {

176:   pc->diagonalscale     = PETSC_TRUE;

178:   PetscObjectReference((PetscObject)s);
179:   VecDestroy(&pc->diagonalscaleleft);

181:   pc->diagonalscaleleft = s;

183:   VecDuplicate(s,&pc->diagonalscaleright);
184:   VecCopy(s,pc->diagonalscaleright);
185:   VecReciprocal(pc->diagonalscaleright);
186:   return(0);
187: }

189: /*@
190:    PCDiagonalScaleLeft - Scales a vector by the left scaling as needed by certain time-stepping codes.

192:    Logically Collective on PC

194:    Input Parameters:
195: +  pc - the preconditioner context
196: .  in - input vector
197: -  out - scaled vector (maybe the same as in)

199:    Level: intermediate

201:    Notes:
202:     The system solved via the Krylov method is
203: $           D M A D^{-1} y = D M b  for left preconditioning or
204: $           D A M D^{-1} z = D b for right preconditioning

206:    PCDiagonalScaleLeft() scales a vector by D. PCDiagonalScaleRight() scales a vector by D^{-1}.

208:    If diagonal scaling is turned off and in is not out then in is copied to out

210: .seealso: PCCreate(), PCSetUp(), PCDiagonalScaleSet(), PCDiagonalScaleRight(), PCDiagonalScale()
211: @*/
212: PetscErrorCode  PCDiagonalScaleLeft(PC pc,Vec in,Vec out)
213: {

220:   if (pc->diagonalscale) {
221:     VecPointwiseMult(out,pc->diagonalscaleleft,in);
222:   } else if (in != out) {
223:     VecCopy(in,out);
224:   }
225:   return(0);
226: }

228: /*@
229:    PCDiagonalScaleRight - Scales a vector by the right scaling as needed by certain time-stepping codes.

231:    Logically Collective on PC

233:    Input Parameters:
234: +  pc - the preconditioner context
235: .  in - input vector
236: -  out - scaled vector (maybe the same as in)

238:    Level: intermediate

240:    Notes:
241:     The system solved via the Krylov method is
242: $           D M A D^{-1} y = D M b  for left preconditioning or
243: $           D A M D^{-1} z = D b for right preconditioning

245:    PCDiagonalScaleLeft() scales a vector by D. PCDiagonalScaleRight() scales a vector by D^{-1}.

247:    If diagonal scaling is turned off and in is not out then in is copied to out

249: .seealso: PCCreate(), PCSetUp(), PCDiagonalScaleLeft(), PCDiagonalScaleSet(), PCDiagonalScale()
250: @*/
251: PetscErrorCode  PCDiagonalScaleRight(PC pc,Vec in,Vec out)
252: {

259:   if (pc->diagonalscale) {
260:     VecPointwiseMult(out,pc->diagonalscaleright,in);
261:   } else if (in != out) {
262:     VecCopy(in,out);
263:   }
264:   return(0);
265: }

267: /*@
268:    PCSetUseAmat - Sets a flag to indicate that when the preconditioner needs to apply (part of) the
269:    operator during the preconditioning process it applies the Amat provided to TSSetRHSJacobian(),
270:    TSSetIJacobian(), SNESSetJacobian(), KSPSetOperator() or PCSetOperator() not the Pmat.

272:    Logically Collective on PC

274:    Input Parameters:
275: +  pc - the preconditioner context
276: -  flg - PETSC_TRUE to use the Amat, PETSC_FALSE to use the Pmat (default is false)

278:    Options Database Key:
279: .  -pc_use_amat <true,false>

281:    Notes:
282:    For the common case in which the linear system matrix and the matrix used to construct the
283:    preconditioner are identical, this routine is does nothing.

285:    Level: intermediate

287: .seealso: PCGetUseAmat(), PCBJACOBI, PGMG, PCFIELDSPLIT, PCCOMPOSITE
288: @*/
289: PetscErrorCode  PCSetUseAmat(PC pc,PetscBool flg)
290: {
293:   pc->useAmat = flg;
294:   return(0);
295: }

297: /*@
298:    PCSetErrorIfFailure - Causes PC to generate an error if a FPE, for example a zero pivot, is detected.

300:    Logically Collective on PC

302:    Input Parameters:
303: +  pc - iterative context obtained from PCCreate()
304: -  flg - PETSC_TRUE indicates you want the error generated

306:    Level: advanced

308:    Notes:
309:     Normally PETSc continues if a linear solver fails due to a failed setup of a preconditioner, you can call KSPGetConvergedReason() after a KSPSolve()
310:     to determine if it has converged or failed. Or use -ksp_error_if_not_converged to cause the program to terminate as soon as lack of convergence is
311:     detected.

313:     This is propagated into KSPs used by this PC, which then propagate it into PCs used by those KSPs

315: .seealso: PCGetInitialGuessNonzero(), PCSetInitialGuessKnoll(), PCGetInitialGuessKnoll()
316: @*/
317: PetscErrorCode  PCSetErrorIfFailure(PC pc,PetscBool flg)
318: {
322:   pc->erroriffailure = flg;
323:   return(0);
324: }

326: /*@
327:    PCGetUseAmat - Gets a flag to indicate that when the preconditioner needs to apply (part of) the
328:    operator during the preconditioning process it applies the Amat provided to TSSetRHSJacobian(),
329:    TSSetIJacobian(), SNESSetJacobian(), KSPSetOperator() or PCSetOperator() not the Pmat.

331:    Logically Collective on PC

333:    Input Parameter:
334: .  pc - the preconditioner context

336:    Output Parameter:
337: .  flg - PETSC_TRUE to use the Amat, PETSC_FALSE to use the Pmat (default is false)

339:    Notes:
340:    For the common case in which the linear system matrix and the matrix used to construct the
341:    preconditioner are identical, this routine is does nothing.

343:    Level: intermediate

345: .seealso: PCSetUseAmat(), PCBJACOBI, PGMG, PCFIELDSPLIT, PCCOMPOSITE
346: @*/
347: PetscErrorCode  PCGetUseAmat(PC pc,PetscBool *flg)
348: {
351:   *flg = pc->useAmat;
352:   return(0);
353: }

355: /*@
356:    PCCreate - Creates a preconditioner context.

358:    Collective

360:    Input Parameter:
361: .  comm - MPI communicator

363:    Output Parameter:
364: .  pc - location to put the preconditioner context

366:    Notes:
367:    The default preconditioner for sparse matrices is PCILU or PCICC with 0 fill on one process and block Jacobi with PCILU or PCICC
368:    in parallel. For dense matrices it is always PCNONE.

370:    Level: developer

372: .seealso: PCSetUp(), PCApply(), PCDestroy()
373: @*/
374: PetscErrorCode  PCCreate(MPI_Comm comm,PC *newpc)
375: {
376:   PC             pc;

381:   *newpc = NULL;
382:   PCInitializePackage();

384:   PetscHeaderCreate(pc,PC_CLASSID,"PC","Preconditioner","PC",comm,PCDestroy,PCView);

386:   pc->mat                  = NULL;
387:   pc->pmat                 = NULL;
388:   pc->setupcalled          = 0;
389:   pc->setfromoptionscalled = 0;
390:   pc->data                 = NULL;
391:   pc->diagonalscale        = PETSC_FALSE;
392:   pc->diagonalscaleleft    = NULL;
393:   pc->diagonalscaleright   = NULL;

395:   pc->modifysubmatrices  = NULL;
396:   pc->modifysubmatricesP = NULL;

398:   *newpc = pc;
399:   return(0);

401: }

403: /* -------------------------------------------------------------------------------*/

405: /*@
406:    PCApply - Applies the preconditioner to a vector.

408:    Collective on PC

410:    Input Parameters:
411: +  pc - the preconditioner context
412: -  x - input vector

414:    Output Parameter:
415: .  y - output vector

417:    Level: developer

419: .seealso: PCApplyTranspose(), PCApplyBAorAB()
420: @*/
421: PetscErrorCode  PCApply(PC pc,Vec x,Vec y)
422: {
424:   PetscInt       m,n,mv,nv;

430:   if (x == y) SETERRQ(PetscObjectComm((PetscObject)pc),PETSC_ERR_ARG_IDN,"x and y must be different vectors");
431:   if (pc->erroriffailure) {VecValidValues(x,2,PETSC_TRUE);}
432:   /* use pmat to check vector sizes since for KSPLQR the pmat may be of a different size than mat */
433:   MatGetLocalSize(pc->pmat,&m,&n);
434:   VecGetLocalSize(x,&nv);
435:   VecGetLocalSize(y,&mv);
436:   if (mv != m) SETERRQ2(PETSC_COMM_SELF,PETSC_ERR_ARG_SIZ,"Preconditioner number of local rows %D does not equal resulting vector number of rows %D",m,mv);
437:   if (nv != n) SETERRQ2(PETSC_COMM_SELF,PETSC_ERR_ARG_SIZ,"Preconditioner number of local columns %D does not equal resulting vector number of rows %D",n,nv);
438:   VecSetErrorIfLocked(y,3);

440:   PCSetUp(pc);
441:   if (!pc->ops->apply) SETERRQ(PetscObjectComm((PetscObject)pc),PETSC_ERR_SUP,"PC does not have apply");
442:   VecLockReadPush(x);
443:   PetscLogEventBegin(PC_Apply,pc,x,y,0);
444:   (*pc->ops->apply)(pc,x,y);
445:   PetscLogEventEnd(PC_Apply,pc,x,y,0);
446:   if (pc->erroriffailure) {VecValidValues(y,3,PETSC_FALSE);}
447:   VecLockReadPop(x);
448:   return(0);
449: }

451: /*@
452:    PCMatApply - Applies the preconditioner to multiple vectors stored as a MATDENSE. Like PCApply(), Y and X must be different matrices.

454:    Collective on PC

456:    Input Parameters:
457: +  pc - the preconditioner context
458: -  X - block of input vectors

460:    Output Parameter:
461: .  Y - block of output vectors

463:    Level: developer

465: .seealso: PCApply(), KSPMatSolve()
466: @*/
467: PetscErrorCode  PCMatApply(PC pc,Mat X,Mat Y)
468: {
469:   Mat            A;
470:   Vec            cy, cx;
471:   PetscInt       m1, M1, m2, M2, n1, N1, n2, N2;
472:   PetscBool      match;

481:   if (Y == X) SETERRQ(PetscObjectComm((PetscObject)pc), PETSC_ERR_ARG_IDN, "Y and X must be different matrices");
482:   PCGetOperators(pc, NULL, &A);
483:   MatGetLocalSize(A, &m1, NULL);
484:   MatGetLocalSize(Y, &m2, &n2);
485:   MatGetSize(A, &M1, NULL);
486:   MatGetSize(X, &M2, &N2);
487:   if (m1 != m2 || M1 != M2) SETERRQ4(PETSC_COMM_SELF, PETSC_ERR_ARG_SIZ, "Cannot use a block of input vectors with (m2,M2) = (%D,%D) for a preconditioner with (m1,M1) = (%D,%D)", m2, M2, m1, M1);
488:   MatGetLocalSize(Y, &m1, &n1);
489:   MatGetSize(Y, &M1, &N1);
490:   if (m1 != m2 || M1 != M2 || n1 != n2 || N1 != N2) SETERRQ8(PETSC_COMM_SELF, PETSC_ERR_ARG_SIZ, "Incompatible block of input vectors (m2,M2)x(n2,N2) = (%D,%D)x(%D,%D) and output vectors (m1,M1)x(n1,N1) = (%D,%D)x(%D,%D)", m2, M2, n2, N2, m1, M1, n1, N1);
491:   PetscObjectBaseTypeCompareAny((PetscObject)Y, &match, MATSEQDENSE, MATMPIDENSE, "");
492:   if (!match) SETERRQ(PETSC_COMM_SELF, PETSC_ERR_ARG_WRONG, "Provided block of output vectors not stored in a dense Mat");
493:   PetscObjectBaseTypeCompareAny((PetscObject)X, &match, MATSEQDENSE, MATMPIDENSE, "");
494:   if (!match) SETERRQ(PETSC_COMM_SELF, PETSC_ERR_ARG_WRONG, "Provided block of input vectors not stored in a dense Mat");
495:   PCSetUp(pc);
496:   if (pc->ops->matapply) {
497:     PetscLogEventBegin(PC_MatApply, pc, X, Y, 0);
498:     (*pc->ops->matapply)(pc, X, Y);
499:     PetscLogEventEnd(PC_MatApply, pc, X, Y, 0);
500:   } else {
501:     PetscInfo1(pc, "PC type %s applying column by column\n", ((PetscObject)pc)->type_name);
502:     for (n2 = 0; n2 < N2; ++n2) {
503:       MatDenseGetColumnVecRead(X, n2, &cx);
504:       MatDenseGetColumnVecWrite(Y, n2, &cy);
505:       PCApply(pc, cx, cy);
506:       MatDenseRestoreColumnVecWrite(Y, n2, &cy);
507:       MatDenseRestoreColumnVecRead(X, n2, &cx);
508:     }
509:   }
510:   return(0);
511: }

513: /*@
514:    PCApplySymmetricLeft - Applies the left part of a symmetric preconditioner to a vector.

516:    Collective on PC

518:    Input Parameters:
519: +  pc - the preconditioner context
520: -  x - input vector

522:    Output Parameter:
523: .  y - output vector

525:    Notes:
526:    Currently, this routine is implemented only for PCICC and PCJACOBI preconditioners.

528:    Level: developer

530: .seealso: PCApply(), PCApplySymmetricRight()
531: @*/
532: PetscErrorCode  PCApplySymmetricLeft(PC pc,Vec x,Vec y)
533: {

540:   if (x == y) SETERRQ(PetscObjectComm((PetscObject)pc),PETSC_ERR_ARG_IDN,"x and y must be different vectors");
541:   if (pc->erroriffailure) {VecValidValues(x,2,PETSC_TRUE);}
542:   PCSetUp(pc);
543:   if (!pc->ops->applysymmetricleft) SETERRQ(PetscObjectComm((PetscObject)pc),PETSC_ERR_SUP,"PC does not have left symmetric apply");
544:   VecLockReadPush(x);
545:   PetscLogEventBegin(PC_ApplySymmetricLeft,pc,x,y,0);
546:   (*pc->ops->applysymmetricleft)(pc,x,y);
547:   PetscLogEventEnd(PC_ApplySymmetricLeft,pc,x,y,0);
548:   VecLockReadPop(x);
549:   if (pc->erroriffailure) {VecValidValues(y,3,PETSC_FALSE);}
550:   return(0);
551: }

553: /*@
554:    PCApplySymmetricRight - Applies the right part of a symmetric preconditioner to a vector.

556:    Collective on PC

558:    Input Parameters:
559: +  pc - the preconditioner context
560: -  x - input vector

562:    Output Parameter:
563: .  y - output vector

565:    Level: developer

567:    Notes:
568:    Currently, this routine is implemented only for PCICC and PCJACOBI preconditioners.

570: .seealso: PCApply(), PCApplySymmetricLeft()
571: @*/
572: PetscErrorCode  PCApplySymmetricRight(PC pc,Vec x,Vec y)
573: {

580:   if (x == y) SETERRQ(PetscObjectComm((PetscObject)pc),PETSC_ERR_ARG_IDN,"x and y must be different vectors");
581:   if (pc->erroriffailure) {VecValidValues(x,2,PETSC_TRUE);}
582:   PCSetUp(pc);
583:   if (!pc->ops->applysymmetricright) SETERRQ(PetscObjectComm((PetscObject)pc),PETSC_ERR_SUP,"PC does not have left symmetric apply");
584:   VecLockReadPush(x);
585:   PetscLogEventBegin(PC_ApplySymmetricRight,pc,x,y,0);
586:   (*pc->ops->applysymmetricright)(pc,x,y);
587:   PetscLogEventEnd(PC_ApplySymmetricRight,pc,x,y,0);
588:   VecLockReadPop(x);
589:   if (pc->erroriffailure) {VecValidValues(y,3,PETSC_FALSE);}
590:   return(0);
591: }

593: /*@
594:    PCApplyTranspose - Applies the transpose of preconditioner to a vector.

596:    Collective on PC

598:    Input Parameters:
599: +  pc - the preconditioner context
600: -  x - input vector

602:    Output Parameter:
603: .  y - output vector

605:    Notes:
606:     For complex numbers this applies the non-Hermitian transpose.

608:    Developer Notes:
609:     We need to implement a PCApplyHermitianTranspose()

611:    Level: developer

613: .seealso: PCApply(), PCApplyBAorAB(), PCApplyBAorABTranspose(), PCApplyTransposeExists()
614: @*/
615: PetscErrorCode  PCApplyTranspose(PC pc,Vec x,Vec y)
616: {

623:   if (x == y) SETERRQ(PetscObjectComm((PetscObject)pc),PETSC_ERR_ARG_IDN,"x and y must be different vectors");
624:   if (pc->erroriffailure) {VecValidValues(x,2,PETSC_TRUE);}
625:   PCSetUp(pc);
626:   if (!pc->ops->applytranspose) SETERRQ(PetscObjectComm((PetscObject)pc),PETSC_ERR_SUP,"PC does not have apply transpose");
627:   VecLockReadPush(x);
628:   PetscLogEventBegin(PC_Apply,pc,x,y,0);
629:   (*pc->ops->applytranspose)(pc,x,y);
630:   PetscLogEventEnd(PC_Apply,pc,x,y,0);
631:   VecLockReadPop(x);
632:   if (pc->erroriffailure) {VecValidValues(y,3,PETSC_FALSE);}
633:   return(0);
634: }

636: /*@
637:    PCApplyTransposeExists - Test whether the preconditioner has a transpose apply operation

639:    Collective on PC

641:    Input Parameters:
642: .  pc - the preconditioner context

644:    Output Parameter:
645: .  flg - PETSC_TRUE if a transpose operation is defined

647:    Level: developer

649: .seealso: PCApplyTranspose()
650: @*/
651: PetscErrorCode  PCApplyTransposeExists(PC pc,PetscBool  *flg)
652: {
656:   if (pc->ops->applytranspose) *flg = PETSC_TRUE;
657:   else *flg = PETSC_FALSE;
658:   return(0);
659: }

661: /*@
662:    PCApplyBAorAB - Applies the preconditioner and operator to a vector. y = B*A*x or y = A*B*x.

664:    Collective on PC

666:    Input Parameters:
667: +  pc - the preconditioner context
668: .  side - indicates the preconditioner side, one of PC_LEFT, PC_RIGHT, or PC_SYMMETRIC
669: .  x - input vector
670: -  work - work vector

672:    Output Parameter:
673: .  y - output vector

675:    Level: developer

677:    Notes:
678:     If the PC has had PCSetDiagonalScale() set then D M A D^{-1} for left preconditioning or  D A M D^{-1} is actually applied. Note that the
679:    specific KSPSolve() method must also be written to handle the post-solve "correction" for the diagonal scaling.

681: .seealso: PCApply(), PCApplyTranspose(), PCApplyBAorABTranspose()
682: @*/
683: PetscErrorCode  PCApplyBAorAB(PC pc,PCSide side,Vec x,Vec y,Vec work)
684: {

696:   if (x == y) SETERRQ(PetscObjectComm((PetscObject)pc),PETSC_ERR_ARG_IDN,"x and y must be different vectors");
697:   if (side != PC_LEFT && side != PC_SYMMETRIC && side != PC_RIGHT) SETERRQ(PetscObjectComm((PetscObject)pc),PETSC_ERR_ARG_OUTOFRANGE,"Side must be right, left, or symmetric");
698:   if (pc->diagonalscale && side == PC_SYMMETRIC) SETERRQ(PetscObjectComm((PetscObject)pc),PETSC_ERR_SUP,"Cannot include diagonal scaling with symmetric preconditioner application");
699:   if (pc->erroriffailure) {VecValidValues(x,3,PETSC_TRUE);}

701:   PCSetUp(pc);
702:   if (pc->diagonalscale) {
703:     if (pc->ops->applyBA) {
704:       Vec work2; /* this is expensive, but to fix requires a second work vector argument to PCApplyBAorAB() */
705:       VecDuplicate(x,&work2);
706:       PCDiagonalScaleRight(pc,x,work2);
707:       (*pc->ops->applyBA)(pc,side,work2,y,work);
708:       PCDiagonalScaleLeft(pc,y,y);
709:       VecDestroy(&work2);
710:     } else if (side == PC_RIGHT) {
711:       PCDiagonalScaleRight(pc,x,y);
712:       PCApply(pc,y,work);
713:       MatMult(pc->mat,work,y);
714:       PCDiagonalScaleLeft(pc,y,y);
715:     } else if (side == PC_LEFT) {
716:       PCDiagonalScaleRight(pc,x,y);
717:       MatMult(pc->mat,y,work);
718:       PCApply(pc,work,y);
719:       PCDiagonalScaleLeft(pc,y,y);
720:     } else if (side == PC_SYMMETRIC) SETERRQ(PetscObjectComm((PetscObject)pc),PETSC_ERR_SUP,"Cannot provide diagonal scaling with symmetric application of preconditioner");
721:   } else {
722:     if (pc->ops->applyBA) {
723:       (*pc->ops->applyBA)(pc,side,x,y,work);
724:     } else if (side == PC_RIGHT) {
725:       PCApply(pc,x,work);
726:       MatMult(pc->mat,work,y);
727:     } else if (side == PC_LEFT) {
728:       MatMult(pc->mat,x,work);
729:       PCApply(pc,work,y);
730:     } else if (side == PC_SYMMETRIC) {
731:       /* There's an extra copy here; maybe should provide 2 work vectors instead? */
732:       PCApplySymmetricRight(pc,x,work);
733:       MatMult(pc->mat,work,y);
734:       VecCopy(y,work);
735:       PCApplySymmetricLeft(pc,work,y);
736:     }
737:   }
738:   if (pc->erroriffailure) {VecValidValues(y,4,PETSC_FALSE);}
739:   return(0);
740: }

742: /*@
743:    PCApplyBAorABTranspose - Applies the transpose of the preconditioner
744:    and operator to a vector. That is, applies tr(B) * tr(A) with left preconditioning,
745:    NOT tr(B*A) = tr(A)*tr(B).

747:    Collective on PC

749:    Input Parameters:
750: +  pc - the preconditioner context
751: .  side - indicates the preconditioner side, one of PC_LEFT, PC_RIGHT, or PC_SYMMETRIC
752: .  x - input vector
753: -  work - work vector

755:    Output Parameter:
756: .  y - output vector


759:    Notes:
760:     this routine is used internally so that the same Krylov code can be used to solve A x = b and A' x = b, with a preconditioner
761:       defined by B'. This is why this has the funny form that it computes tr(B) * tr(A)

763:     Level: developer

765: .seealso: PCApply(), PCApplyTranspose(), PCApplyBAorAB()
766: @*/
767: PetscErrorCode  PCApplyBAorABTranspose(PC pc,PCSide side,Vec x,Vec y,Vec work)
768: {

776:   if (x == y) SETERRQ(PetscObjectComm((PetscObject)pc),PETSC_ERR_ARG_IDN,"x and y must be different vectors");
777:   if (pc->erroriffailure) {VecValidValues(x,3,PETSC_TRUE);}
778:   if (pc->ops->applyBAtranspose) {
779:     (*pc->ops->applyBAtranspose)(pc,side,x,y,work);
780:     if (pc->erroriffailure) {VecValidValues(y,4,PETSC_FALSE);}
781:     return(0);
782:   }
783:   if (side != PC_LEFT && side != PC_RIGHT) SETERRQ(PetscObjectComm((PetscObject)pc),PETSC_ERR_ARG_OUTOFRANGE,"Side must be right or left");

785:   PCSetUp(pc);
786:   if (side == PC_RIGHT) {
787:     PCApplyTranspose(pc,x,work);
788:     MatMultTranspose(pc->mat,work,y);
789:   } else if (side == PC_LEFT) {
790:     MatMultTranspose(pc->mat,x,work);
791:     PCApplyTranspose(pc,work,y);
792:   }
793:   /* add support for PC_SYMMETRIC */
794:   if (pc->erroriffailure) {VecValidValues(y,4,PETSC_FALSE);}
795:   return(0);
796: }

798: /* -------------------------------------------------------------------------------*/

800: /*@
801:    PCApplyRichardsonExists - Determines whether a particular preconditioner has a
802:    built-in fast application of Richardson's method.

804:    Not Collective

806:    Input Parameter:
807: .  pc - the preconditioner

809:    Output Parameter:
810: .  exists - PETSC_TRUE or PETSC_FALSE

812:    Level: developer

814: .seealso: PCApplyRichardson()
815: @*/
816: PetscErrorCode  PCApplyRichardsonExists(PC pc,PetscBool  *exists)
817: {
821:   if (pc->ops->applyrichardson) *exists = PETSC_TRUE;
822:   else *exists = PETSC_FALSE;
823:   return(0);
824: }

826: /*@
827:    PCApplyRichardson - Applies several steps of Richardson iteration with
828:    the particular preconditioner. This routine is usually used by the
829:    Krylov solvers and not the application code directly.

831:    Collective on PC

833:    Input Parameters:
834: +  pc  - the preconditioner context
835: .  b   - the right hand side
836: .  w   - one work vector
837: .  rtol - relative decrease in residual norm convergence criteria
838: .  abstol - absolute residual norm convergence criteria
839: .  dtol - divergence residual norm increase criteria
840: .  its - the number of iterations to apply.
841: -  guesszero - if the input x contains nonzero initial guess

843:    Output Parameter:
844: +  outits - number of iterations actually used (for SOR this always equals its)
845: .  reason - the reason the apply terminated
846: -  y - the solution (also contains initial guess if guesszero is PETSC_FALSE

848:    Notes:
849:    Most preconditioners do not support this function. Use the command
850:    PCApplyRichardsonExists() to determine if one does.

852:    Except for the multigrid PC this routine ignores the convergence tolerances
853:    and always runs for the number of iterations

855:    Level: developer

857: .seealso: PCApplyRichardsonExists()
858: @*/
859: PetscErrorCode  PCApplyRichardson(PC pc,Vec b,Vec y,Vec w,PetscReal rtol,PetscReal abstol, PetscReal dtol,PetscInt its,PetscBool guesszero,PetscInt *outits,PCRichardsonConvergedReason *reason)
860: {

868:   if (b == y) SETERRQ(PetscObjectComm((PetscObject)pc),PETSC_ERR_ARG_IDN,"b and y must be different vectors");
869:   PCSetUp(pc);
870:   if (!pc->ops->applyrichardson) SETERRQ(PetscObjectComm((PetscObject)pc),PETSC_ERR_SUP,"PC does not have apply richardson");
871:   (*pc->ops->applyrichardson)(pc,b,y,w,rtol,abstol,dtol,its,guesszero,outits,reason);
872:   return(0);
873: }

875: /*@
876:    PCSetFailedReason - Sets the reason a PCSetUp() failed or PC_NOERROR if it did not fail

878:    Logically Collective on PC

880:    Input Parameter:
881: +  pc - the preconditioner context
882: -  reason - the reason it failedx

884:    Level: advanced

886: .seealso: PCCreate(), PCApply(), PCDestroy(), PCFailedReason
887: @*/
888: PetscErrorCode PCSetFailedReason(PC pc,PCFailedReason reason)
889: {
891:   pc->failedreason = reason;
892:   return(0);
893: }

895: /*@
896:    PCGetFailedReason - Gets the reason a PCSetUp() failed or PC_NOERROR if it did not fail

898:    Logically Collective on PC

900:    Input Parameter:
901: .  pc - the preconditioner context

903:    Output Parameter:
904: .  reason - the reason it failed

906:    Level: advanced

908:    Notes: This is the maximum over reason over all ranks in the PC communicator. It is only valid after
909:    a call KSPCheckDot() or  KSPCheckNorm() inside a KSPSolve(). It is not valid immediately after a PCSetUp()
910:    or PCApply(), then use PCGetFailedReasonRank()

912: .seealso: PCCreate(), PCApply(), PCDestroy(), PCGetFailedReasonRank(), PCSetFailedReason()
913: @*/
914: PetscErrorCode PCGetFailedReason(PC pc,PCFailedReason *reason)
915: {
917:   if (pc->setupcalled < 0) *reason = (PCFailedReason)pc->setupcalled;
918:   else *reason = pc->failedreason;
919:   return(0);
920: }

922: /*@
923:    PCGetFailedReasonRank - Gets the reason a PCSetUp() failed or PC_NOERROR if it did not fail on this MPI rank

925:   Not Collective on PC

927:    Input Parameter:
928: .  pc - the preconditioner context

930:    Output Parameter:
931: .  reason - the reason it failed

933:    Notes:
934:      Different ranks may have different reasons or no reason, see PCGetFailedReason()

936:    Level: advanced

938: .seealso: PCCreate(), PCApply(), PCDestroy(), PCGetFailedReason(), PCSetFailedReason()
939: @*/
940: PetscErrorCode PCGetFailedReasonRank(PC pc,PCFailedReason *reason)
941: {
943:   if (pc->setupcalled < 0) *reason = (PCFailedReason)pc->setupcalled;
944:   else *reason = pc->failedreason;
945:   return(0);
946: }

948: /*
949:       a setupcall of 0 indicates never setup,
950:                      1 indicates has been previously setup
951:                     -1 indicates a PCSetUp() was attempted and failed
952: */
953: /*@
954:    PCSetUp - Prepares for the use of a preconditioner.

956:    Collective on PC

958:    Input Parameter:
959: .  pc - the preconditioner context

961:    Level: developer

963: .seealso: PCCreate(), PCApply(), PCDestroy()
964: @*/
965: PetscErrorCode  PCSetUp(PC pc)
966: {
967:   PetscErrorCode   ierr;
968:   const char       *def;
969:   PetscObjectState matstate, matnonzerostate;

973:   if (!pc->mat) SETERRQ(PetscObjectComm((PetscObject)pc),PETSC_ERR_ARG_WRONGSTATE,"Matrix must be set first");

975:   if (pc->setupcalled && pc->reusepreconditioner) {
976:     PetscInfo(pc,"Leaving PC with identical preconditioner since reuse preconditioner is set\n");
977:     return(0);
978:   }

980:   PetscObjectStateGet((PetscObject)pc->pmat,&matstate);
981:   MatGetNonzeroState(pc->pmat,&matnonzerostate);
982:   if (!pc->setupcalled) {
983:     PetscInfo(pc,"Setting up PC for first time\n");
984:     pc->flag = DIFFERENT_NONZERO_PATTERN;
985:   } else if (matstate == pc->matstate) {
986:     PetscInfo(pc,"Leaving PC with identical preconditioner since operator is unchanged\n");
987:     return(0);
988:   } else {
989:     if (matnonzerostate > pc->matnonzerostate) {
990:        PetscInfo(pc,"Setting up PC with different nonzero pattern\n");
991:        pc->flag = DIFFERENT_NONZERO_PATTERN;
992:     } else {
993:       PetscInfo(pc,"Setting up PC with same nonzero pattern\n");
994:       pc->flag = SAME_NONZERO_PATTERN;
995:     }
996:   }
997:   pc->matstate        = matstate;
998:   pc->matnonzerostate = matnonzerostate;

1000:   if (!((PetscObject)pc)->type_name) {
1001:     PCGetDefaultType_Private(pc,&def);
1002:     PCSetType(pc,def);
1003:   }

1005:   MatSetErrorIfFailure(pc->pmat,pc->erroriffailure);
1006:   MatSetErrorIfFailure(pc->mat,pc->erroriffailure);
1007:   PetscLogEventBegin(PC_SetUp,pc,0,0,0);
1008:   if (pc->ops->setup) {
1009:     (*pc->ops->setup)(pc);
1010:   }
1011:   PetscLogEventEnd(PC_SetUp,pc,0,0,0);
1012:   if (!pc->setupcalled) pc->setupcalled = 1;
1013:   return(0);
1014: }

1016: /*@
1017:    PCSetUpOnBlocks - Sets up the preconditioner for each block in
1018:    the block Jacobi, block Gauss-Seidel, and overlapping Schwarz
1019:    methods.

1021:    Collective on PC

1023:    Input Parameters:
1024: .  pc - the preconditioner context

1026:    Level: developer

1028: .seealso: PCCreate(), PCApply(), PCDestroy(), PCSetUp()
1029: @*/
1030: PetscErrorCode  PCSetUpOnBlocks(PC pc)
1031: {

1036:   if (!pc->ops->setuponblocks) return(0);
1037:   PetscLogEventBegin(PC_SetUpOnBlocks,pc,0,0,0);
1038:   (*pc->ops->setuponblocks)(pc);
1039:   PetscLogEventEnd(PC_SetUpOnBlocks,pc,0,0,0);
1040:   return(0);
1041: }

1043: /*@C
1044:    PCSetModifySubMatrices - Sets a user-defined routine for modifying the
1045:    submatrices that arise within certain subdomain-based preconditioners.
1046:    The basic submatrices are extracted from the preconditioner matrix as
1047:    usual; the user can then alter these (for example, to set different boundary
1048:    conditions for each submatrix) before they are used for the local solves.

1050:    Logically Collective on PC

1052:    Input Parameters:
1053: +  pc - the preconditioner context
1054: .  func - routine for modifying the submatrices
1055: -  ctx - optional user-defined context (may be null)

1057:    Calling sequence of func:
1058: $     func (PC pc,PetscInt nsub,IS *row,IS *col,Mat *submat,void *ctx);

1060: +  row - an array of index sets that contain the global row numbers
1061:          that comprise each local submatrix
1062: .  col - an array of index sets that contain the global column numbers
1063:          that comprise each local submatrix
1064: .  submat - array of local submatrices
1065: -  ctx - optional user-defined context for private data for the
1066:          user-defined func routine (may be null)

1068:    Notes:
1069:    PCSetModifySubMatrices() MUST be called before KSPSetUp() and
1070:    KSPSolve().

1072:    A routine set by PCSetModifySubMatrices() is currently called within
1073:    the block Jacobi (PCBJACOBI) and additive Schwarz (PCASM)
1074:    preconditioners.  All other preconditioners ignore this routine.

1076:    Level: advanced

1078: .seealso: PCModifySubMatrices()
1079: @*/
1080: PetscErrorCode  PCSetModifySubMatrices(PC pc,PetscErrorCode (*func)(PC,PetscInt,const IS[],const IS[],Mat[],void*),void *ctx)
1081: {
1084:   pc->modifysubmatrices  = func;
1085:   pc->modifysubmatricesP = ctx;
1086:   return(0);
1087: }

1089: /*@C
1090:    PCModifySubMatrices - Calls an optional user-defined routine within
1091:    certain preconditioners if one has been set with PCSetModifySubMatrices().

1093:    Collective on PC

1095:    Input Parameters:
1096: +  pc - the preconditioner context
1097: .  nsub - the number of local submatrices
1098: .  row - an array of index sets that contain the global row numbers
1099:          that comprise each local submatrix
1100: .  col - an array of index sets that contain the global column numbers
1101:          that comprise each local submatrix
1102: .  submat - array of local submatrices
1103: -  ctx - optional user-defined context for private data for the
1104:          user-defined routine (may be null)

1106:    Output Parameter:
1107: .  submat - array of local submatrices (the entries of which may
1108:             have been modified)

1110:    Notes:
1111:    The user should NOT generally call this routine, as it will
1112:    automatically be called within certain preconditioners (currently
1113:    block Jacobi, additive Schwarz) if set.

1115:    The basic submatrices are extracted from the preconditioner matrix
1116:    as usual; the user can then alter these (for example, to set different
1117:    boundary conditions for each submatrix) before they are used for the
1118:    local solves.

1120:    Level: developer

1122: .seealso: PCSetModifySubMatrices()
1123: @*/
1124: PetscErrorCode  PCModifySubMatrices(PC pc,PetscInt nsub,const IS row[],const IS col[],Mat submat[],void *ctx)
1125: {

1130:   if (!pc->modifysubmatrices) return(0);
1131:   PetscLogEventBegin(PC_ModifySubMatrices,pc,0,0,0);
1132:   (*pc->modifysubmatrices)(pc,nsub,row,col,submat,ctx);
1133:   PetscLogEventEnd(PC_ModifySubMatrices,pc,0,0,0);
1134:   return(0);
1135: }

1137: /*@
1138:    PCSetOperators - Sets the matrix associated with the linear system and
1139:    a (possibly) different one associated with the preconditioner.

1141:    Logically Collective on PC

1143:    Input Parameters:
1144: +  pc - the preconditioner context
1145: .  Amat - the matrix that defines the linear system
1146: -  Pmat - the matrix to be used in constructing the preconditioner, usually the same as Amat.

1148:    Notes:
1149:     Passing a NULL for Amat or Pmat removes the matrix that is currently used.

1151:     If you wish to replace either Amat or Pmat but leave the other one untouched then
1152:     first call KSPGetOperators() to get the one you wish to keep, call PetscObjectReference()
1153:     on it and then pass it back in in your call to KSPSetOperators().

1155:    More Notes about Repeated Solution of Linear Systems:
1156:    PETSc does NOT reset the matrix entries of either Amat or Pmat
1157:    to zero after a linear solve; the user is completely responsible for
1158:    matrix assembly.  See the routine MatZeroEntries() if desiring to
1159:    zero all elements of a matrix.

1161:    Level: intermediate

1163: .seealso: PCGetOperators(), MatZeroEntries()
1164:  @*/
1165: PetscErrorCode  PCSetOperators(PC pc,Mat Amat,Mat Pmat)
1166: {
1167:   PetscErrorCode   ierr;
1168:   PetscInt         m1,n1,m2,n2;

1176:   if (pc->setupcalled && pc->mat && pc->pmat && Amat && Pmat) {
1177:     MatGetLocalSize(Amat,&m1,&n1);
1178:     MatGetLocalSize(pc->mat,&m2,&n2);
1179:     if (m1 != m2 || n1 != n2) SETERRQ4(PETSC_COMM_SELF,PETSC_ERR_ARG_SIZ,"Cannot change local size of Amat after use old sizes %D %D new sizes %D %D",m2,n2,m1,n1);
1180:     MatGetLocalSize(Pmat,&m1,&n1);
1181:     MatGetLocalSize(pc->pmat,&m2,&n2);
1182:     if (m1 != m2 || n1 != n2) SETERRQ4(PETSC_COMM_SELF,PETSC_ERR_ARG_SIZ,"Cannot change local size of Pmat after use old sizes %D %D new sizes %D %D",m2,n2,m1,n1);
1183:   }

1185:   if (Pmat != pc->pmat) {
1186:     /* changing the operator that defines the preconditioner thus reneed to clear current states so new preconditioner is built */
1187:     pc->matnonzerostate = -1;
1188:     pc->matstate        = -1;
1189:   }

1191:   /* reference first in case the matrices are the same */
1192:   if (Amat) {PetscObjectReference((PetscObject)Amat);}
1193:   MatDestroy(&pc->mat);
1194:   if (Pmat) {PetscObjectReference((PetscObject)Pmat);}
1195:   MatDestroy(&pc->pmat);
1196:   pc->mat  = Amat;
1197:   pc->pmat = Pmat;
1198:   return(0);
1199: }

1201: /*@
1202:    PCSetReusePreconditioner - reuse the current preconditioner even if the operator in the preconditioner has changed.

1204:    Logically Collective on PC

1206:    Input Parameters:
1207: +  pc - the preconditioner context
1208: -  flag - PETSC_TRUE do not compute a new preconditioner, PETSC_FALSE do compute a new preconditioner

1210:     Level: intermediate

1212: .seealso: PCGetOperators(), MatZeroEntries(), PCGetReusePreconditioner(), KSPSetReusePreconditioner()
1213:  @*/
1214: PetscErrorCode  PCSetReusePreconditioner(PC pc,PetscBool flag)
1215: {
1219:   pc->reusepreconditioner = flag;
1220:   return(0);
1221: }

1223: /*@
1224:    PCGetReusePreconditioner - Determines if the PC reuses the current preconditioner even if the operator in the preconditioner has changed.

1226:    Not Collective

1228:    Input Parameter:
1229: .  pc - the preconditioner context

1231:    Output Parameter:
1232: .  flag - PETSC_TRUE do not compute a new preconditioner, PETSC_FALSE do compute a new preconditioner

1234:    Level: intermediate

1236: .seealso: PCGetOperators(), MatZeroEntries(), PCSetReusePreconditioner()
1237:  @*/
1238: PetscErrorCode  PCGetReusePreconditioner(PC pc,PetscBool *flag)
1239: {
1243:   *flag = pc->reusepreconditioner;
1244:   return(0);
1245: }

1247: /*@
1248:    PCGetOperators - Gets the matrix associated with the linear system and
1249:    possibly a different one associated with the preconditioner.

1251:    Not collective, though parallel Mats are returned if the PC is parallel

1253:    Input Parameter:
1254: .  pc - the preconditioner context

1256:    Output Parameters:
1257: +  Amat - the matrix defining the linear system
1258: -  Pmat - the matrix from which the preconditioner is constructed, usually the same as Amat.

1260:    Level: intermediate

1262:    Notes:
1263:     Does not increase the reference count of the matrices, so you should not destroy them

1265:    Alternative usage: If the operators have NOT been set with KSP/PCSetOperators() then the operators
1266:       are created in PC and returned to the user. In this case, if both operators
1267:       mat and pmat are requested, two DIFFERENT operators will be returned. If
1268:       only one is requested both operators in the PC will be the same (i.e. as
1269:       if one had called KSP/PCSetOperators() with the same argument for both Mats).
1270:       The user must set the sizes of the returned matrices and their type etc just
1271:       as if the user created them with MatCreate(). For example,

1273: $         KSP/PCGetOperators(ksp/pc,&Amat,NULL); is equivalent to
1274: $           set size, type, etc of Amat

1276: $         MatCreate(comm,&mat);
1277: $         KSP/PCSetOperators(ksp/pc,Amat,Amat);
1278: $         PetscObjectDereference((PetscObject)mat);
1279: $           set size, type, etc of Amat

1281:      and

1283: $         KSP/PCGetOperators(ksp/pc,&Amat,&Pmat); is equivalent to
1284: $           set size, type, etc of Amat and Pmat

1286: $         MatCreate(comm,&Amat);
1287: $         MatCreate(comm,&Pmat);
1288: $         KSP/PCSetOperators(ksp/pc,Amat,Pmat);
1289: $         PetscObjectDereference((PetscObject)Amat);
1290: $         PetscObjectDereference((PetscObject)Pmat);
1291: $           set size, type, etc of Amat and Pmat

1293:     The rational for this support is so that when creating a TS, SNES, or KSP the hierarchy
1294:     of underlying objects (i.e. SNES, KSP, PC, Mat) and their livespans can be completely
1295:     managed by the top most level object (i.e. the TS, SNES, or KSP). Another way to look
1296:     at this is when you create a SNES you do not NEED to create a KSP and attach it to
1297:     the SNES object (the SNES object manages it for you). Similarly when you create a KSP
1298:     you do not need to attach a PC to it (the KSP object manages the PC object for you).
1299:     Thus, why should YOU have to create the Mat and attach it to the SNES/KSP/PC, when
1300:     it can be created for you?


1303: .seealso: PCSetOperators(), KSPGetOperators(), KSPSetOperators(), PCGetOperatorsSet()
1304: @*/
1305: PetscErrorCode  PCGetOperators(PC pc,Mat *Amat,Mat *Pmat)
1306: {

1311:   if (Amat) {
1312:     if (!pc->mat) {
1313:       if (pc->pmat && !Pmat) {  /* Apmat has been set, but user did not request it, so use for Amat */
1314:         pc->mat = pc->pmat;
1315:         PetscObjectReference((PetscObject)pc->mat);
1316:       } else {                  /* both Amat and Pmat are empty */
1317:         MatCreate(PetscObjectComm((PetscObject)pc),&pc->mat);
1318:         if (!Pmat) { /* user did NOT request Pmat, so make same as Amat */
1319:           pc->pmat = pc->mat;
1320:           PetscObjectReference((PetscObject)pc->pmat);
1321:         }
1322:       }
1323:     }
1324:     *Amat = pc->mat;
1325:   }
1326:   if (Pmat) {
1327:     if (!pc->pmat) {
1328:       if (pc->mat && !Amat) {    /* Amat has been set but was not requested, so use for pmat */
1329:         pc->pmat = pc->mat;
1330:         PetscObjectReference((PetscObject)pc->pmat);
1331:       } else {
1332:         MatCreate(PetscObjectComm((PetscObject)pc),&pc->pmat);
1333:         if (!Amat) { /* user did NOT request Amat, so make same as Pmat */
1334:           pc->mat = pc->pmat;
1335:           PetscObjectReference((PetscObject)pc->mat);
1336:         }
1337:       }
1338:     }
1339:     *Pmat = pc->pmat;
1340:   }
1341:   return(0);
1342: }

1344: /*@C
1345:    PCGetOperatorsSet - Determines if the matrix associated with the linear system and
1346:    possibly a different one associated with the preconditioner have been set in the PC.

1348:    Not collective, though the results on all processes should be the same

1350:    Input Parameter:
1351: .  pc - the preconditioner context

1353:    Output Parameters:
1354: +  mat - the matrix associated with the linear system was set
1355: -  pmat - matrix associated with the preconditioner was set, usually the same

1357:    Level: intermediate

1359: .seealso: PCSetOperators(), KSPGetOperators(), KSPSetOperators(), PCGetOperators()
1360: @*/
1361: PetscErrorCode  PCGetOperatorsSet(PC pc,PetscBool  *mat,PetscBool  *pmat)
1362: {
1365:   if (mat) *mat = (pc->mat)  ? PETSC_TRUE : PETSC_FALSE;
1366:   if (pmat) *pmat = (pc->pmat) ? PETSC_TRUE : PETSC_FALSE;
1367:   return(0);
1368: }

1370: /*@
1371:    PCFactorGetMatrix - Gets the factored matrix from the
1372:    preconditioner context.  This routine is valid only for the LU,
1373:    incomplete LU, Cholesky, and incomplete Cholesky methods.

1375:    Not Collective on PC though Mat is parallel if PC is parallel

1377:    Input Parameters:
1378: .  pc - the preconditioner context

1380:    Output parameters:
1381: .  mat - the factored matrix

1383:    Level: advanced

1385:    Notes:
1386:     Does not increase the reference count for the matrix so DO NOT destroy it

1388: @*/
1389: PetscErrorCode  PCFactorGetMatrix(PC pc,Mat *mat)
1390: {

1396:   if (pc->ops->getfactoredmatrix) {
1397:     (*pc->ops->getfactoredmatrix)(pc,mat);
1398:   } else SETERRQ(PetscObjectComm((PetscObject)pc),PETSC_ERR_SUP,"PC type does not support getting factor matrix");
1399:   return(0);
1400: }

1402: /*@C
1403:    PCSetOptionsPrefix - Sets the prefix used for searching for all
1404:    PC options in the database.

1406:    Logically Collective on PC

1408:    Input Parameters:
1409: +  pc - the preconditioner context
1410: -  prefix - the prefix string to prepend to all PC option requests

1412:    Notes:
1413:    A hyphen (-) must NOT be given at the beginning of the prefix name.
1414:    The first character of all runtime options is AUTOMATICALLY the
1415:    hyphen.

1417:    Level: advanced

1419: .seealso: PCAppendOptionsPrefix(), PCGetOptionsPrefix()
1420: @*/
1421: PetscErrorCode  PCSetOptionsPrefix(PC pc,const char prefix[])
1422: {

1427:   PetscObjectSetOptionsPrefix((PetscObject)pc,prefix);
1428:   return(0);
1429: }

1431: /*@C
1432:    PCAppendOptionsPrefix - Appends to the prefix used for searching for all
1433:    PC options in the database.

1435:    Logically Collective on PC

1437:    Input Parameters:
1438: +  pc - the preconditioner context
1439: -  prefix - the prefix string to prepend to all PC option requests

1441:    Notes:
1442:    A hyphen (-) must NOT be given at the beginning of the prefix name.
1443:    The first character of all runtime options is AUTOMATICALLY the
1444:    hyphen.

1446:    Level: advanced

1448: .seealso: PCSetOptionsPrefix(), PCGetOptionsPrefix()
1449: @*/
1450: PetscErrorCode  PCAppendOptionsPrefix(PC pc,const char prefix[])
1451: {

1456:   PetscObjectAppendOptionsPrefix((PetscObject)pc,prefix);
1457:   return(0);
1458: }

1460: /*@C
1461:    PCGetOptionsPrefix - Gets the prefix used for searching for all
1462:    PC options in the database.

1464:    Not Collective

1466:    Input Parameters:
1467: .  pc - the preconditioner context

1469:    Output Parameters:
1470: .  prefix - pointer to the prefix string used, is returned

1472:    Notes:
1473:     On the fortran side, the user should pass in a string 'prifix' of
1474:    sufficient length to hold the prefix.

1476:    Level: advanced

1478: .seealso: PCSetOptionsPrefix(), PCAppendOptionsPrefix()
1479: @*/
1480: PetscErrorCode  PCGetOptionsPrefix(PC pc,const char *prefix[])
1481: {

1487:   PetscObjectGetOptionsPrefix((PetscObject)pc,prefix);
1488:   return(0);
1489: }

1491: /*
1492:    Indicates the right hand side will be changed by KSPSolve(), this occurs for a few
1493:   preconditioners including BDDC and Eisentat that transform the equations before applying
1494:   the Krylov methods
1495: */
1496: PETSC_INTERN PetscErrorCode  PCPreSolveChangeRHS(PC pc,PetscBool *change)
1497: {

1503:   *change = PETSC_FALSE;
1504:   PetscTryMethod(pc,"PCPreSolveChangeRHS_C",(PC,PetscBool*),(pc,change));
1505:   return(0);
1506: }

1508: /*@
1509:    PCPreSolve - Optional pre-solve phase, intended for any
1510:    preconditioner-specific actions that must be performed before
1511:    the iterative solve itself.

1513:    Collective on PC

1515:    Input Parameters:
1516: +  pc - the preconditioner context
1517: -  ksp - the Krylov subspace context

1519:    Level: developer

1521:    Sample of Usage:
1522: .vb
1523:     PCPreSolve(pc,ksp);
1524:     KSPSolve(ksp,b,x);
1525:     PCPostSolve(pc,ksp);
1526: .ve

1528:    Notes:
1529:    The pre-solve phase is distinct from the PCSetUp() phase.

1531:    KSPSolve() calls this directly, so is rarely called by the user.

1533: .seealso: PCPostSolve()
1534: @*/
1535: PetscErrorCode  PCPreSolve(PC pc,KSP ksp)
1536: {
1538:   Vec            x,rhs;

1543:   pc->presolvedone++;
1544:   if (pc->presolvedone > 2) SETERRQ(PetscObjectComm((PetscObject)pc),PETSC_ERR_SUP,"Cannot embed PCPreSolve() more than twice");
1545:   KSPGetSolution(ksp,&x);
1546:   KSPGetRhs(ksp,&rhs);

1548:   if (pc->ops->presolve) {
1549:     (*pc->ops->presolve)(pc,ksp,rhs,x);
1550:   }
1551:   return(0);
1552: }

1554: /*@
1555:    PCPostSolve - Optional post-solve phase, intended for any
1556:    preconditioner-specific actions that must be performed after
1557:    the iterative solve itself.

1559:    Collective on PC

1561:    Input Parameters:
1562: +  pc - the preconditioner context
1563: -  ksp - the Krylov subspace context

1565:    Sample of Usage:
1566: .vb
1567:     PCPreSolve(pc,ksp);
1568:     KSPSolve(ksp,b,x);
1569:     PCPostSolve(pc,ksp);
1570: .ve

1572:    Note:
1573:    KSPSolve() calls this routine directly, so it is rarely called by the user.

1575:    Level: developer

1577: .seealso: PCPreSolve(), KSPSolve()
1578: @*/
1579: PetscErrorCode  PCPostSolve(PC pc,KSP ksp)
1580: {
1582:   Vec            x,rhs;

1587:   pc->presolvedone--;
1588:   KSPGetSolution(ksp,&x);
1589:   KSPGetRhs(ksp,&rhs);
1590:   if (pc->ops->postsolve) {
1591:      (*pc->ops->postsolve)(pc,ksp,rhs,x);
1592:   }
1593:   return(0);
1594: }

1596: /*@C
1597:   PCLoad - Loads a PC that has been stored in binary  with PCView().

1599:   Collective on PetscViewer

1601:   Input Parameters:
1602: + newdm - the newly loaded PC, this needs to have been created with PCCreate() or
1603:            some related function before a call to PCLoad().
1604: - viewer - binary file viewer, obtained from PetscViewerBinaryOpen()

1606:    Level: intermediate

1608:   Notes:
1609:    The type is determined by the data in the file, any type set into the PC before this call is ignored.

1611:   Notes for advanced users:
1612:   Most users should not need to know the details of the binary storage
1613:   format, since PCLoad() and PCView() completely hide these details.
1614:   But for anyone who's interested, the standard binary matrix storage
1615:   format is
1616: .vb
1617:      has not yet been determined
1618: .ve

1620: .seealso: PetscViewerBinaryOpen(), PCView(), MatLoad(), VecLoad()
1621: @*/
1622: PetscErrorCode  PCLoad(PC newdm, PetscViewer viewer)
1623: {
1625:   PetscBool      isbinary;
1626:   PetscInt       classid;
1627:   char           type[256];

1632:   PetscObjectTypeCompare((PetscObject)viewer,PETSCVIEWERBINARY,&isbinary);
1633:   if (!isbinary) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_WRONG,"Invalid viewer; open viewer with PetscViewerBinaryOpen()");

1635:   PetscViewerBinaryRead(viewer,&classid,1,NULL,PETSC_INT);
1636:   if (classid != PC_FILE_CLASSID) SETERRQ(PetscObjectComm((PetscObject)newdm),PETSC_ERR_ARG_WRONG,"Not PC next in file");
1637:   PetscViewerBinaryRead(viewer,type,256,NULL,PETSC_CHAR);
1638:   PCSetType(newdm, type);
1639:   if (newdm->ops->load) {
1640:     (*newdm->ops->load)(newdm,viewer);
1641:   }
1642:   return(0);
1643: }

1645: #include <petscdraw.h>
1646: #if defined(PETSC_HAVE_SAWS)
1647: #include <petscviewersaws.h>
1648: #endif

1650: /*@C
1651:    PCViewFromOptions - View from Options

1653:    Collective on PC

1655:    Input Parameters:
1656: +  A - the PC context
1657: .  obj - Optional object
1658: -  name - command line option

1660:    Level: intermediate
1661: .seealso:  PC, PCView, PetscObjectViewFromOptions(), PCCreate()
1662: @*/
1663: PetscErrorCode  PCViewFromOptions(PC A,PetscObject obj,const char name[])
1664: {

1669:   PetscObjectViewFromOptions((PetscObject)A,obj,name);
1670:   return(0);
1671: }

1673: /*@C
1674:    PCView - Prints the PC data structure.

1676:    Collective on PC

1678:    Input Parameters:
1679: +  PC - the PC context
1680: -  viewer - optional visualization context

1682:    Note:
1683:    The available visualization contexts include
1684: +     PETSC_VIEWER_STDOUT_SELF - standard output (default)
1685: -     PETSC_VIEWER_STDOUT_WORLD - synchronized standard
1686:          output where only the first processor opens
1687:          the file.  All other processors send their
1688:          data to the first processor to print.

1690:    The user can open an alternative visualization contexts with
1691:    PetscViewerASCIIOpen() (output to a specified file).

1693:    Level: developer

1695: .seealso: KSPView(), PetscViewerASCIIOpen()
1696: @*/
1697: PetscErrorCode  PCView(PC pc,PetscViewer viewer)
1698: {
1699:   PCType         cstr;
1701:   PetscBool      iascii,isstring,isbinary,isdraw;
1702: #if defined(PETSC_HAVE_SAWS)
1703:   PetscBool      issaws;
1704: #endif

1708:   if (!viewer) {
1709:     PetscViewerASCIIGetStdout(PetscObjectComm((PetscObject)pc),&viewer);
1710:   }

1714:   PetscObjectTypeCompare((PetscObject)viewer,PETSCVIEWERASCII,&iascii);
1715:   PetscObjectTypeCompare((PetscObject)viewer,PETSCVIEWERSTRING,&isstring);
1716:   PetscObjectTypeCompare((PetscObject)viewer,PETSCVIEWERBINARY,&isbinary);
1717:   PetscObjectTypeCompare((PetscObject)viewer,PETSCVIEWERDRAW,&isdraw);
1718: #if defined(PETSC_HAVE_SAWS)
1719:   PetscObjectTypeCompare((PetscObject)viewer,PETSCVIEWERSAWS,&issaws);
1720: #endif

1722:   if (iascii) {
1723:     PetscObjectPrintClassNamePrefixType((PetscObject)pc,viewer);
1724:     if (!pc->setupcalled) {
1725:       PetscViewerASCIIPrintf(viewer,"  PC has not been set up so information may be incomplete\n");
1726:     }
1727:     if (pc->ops->view) {
1728:       PetscViewerASCIIPushTab(viewer);
1729:       (*pc->ops->view)(pc,viewer);
1730:       PetscViewerASCIIPopTab(viewer);
1731:     }
1732:     if (pc->mat) {
1733:       PetscViewerPushFormat(viewer,PETSC_VIEWER_ASCII_INFO);
1734:       if (pc->pmat == pc->mat) {
1735:         PetscViewerASCIIPrintf(viewer,"  linear system matrix = precond matrix:\n");
1736:         PetscViewerASCIIPushTab(viewer);
1737:         MatView(pc->mat,viewer);
1738:         PetscViewerASCIIPopTab(viewer);
1739:       } else {
1740:         if (pc->pmat) {
1741:           PetscViewerASCIIPrintf(viewer,"  linear system matrix followed by preconditioner matrix:\n");
1742:         } else {
1743:           PetscViewerASCIIPrintf(viewer,"  linear system matrix:\n");
1744:         }
1745:         PetscViewerASCIIPushTab(viewer);
1746:         MatView(pc->mat,viewer);
1747:         if (pc->pmat) {MatView(pc->pmat,viewer);}
1748:         PetscViewerASCIIPopTab(viewer);
1749:       }
1750:       PetscViewerPopFormat(viewer);
1751:     }
1752:   } else if (isstring) {
1753:     PCGetType(pc,&cstr);
1754:     PetscViewerStringSPrintf(viewer," PCType: %-7.7s",cstr);
1755:     if (pc->ops->view) {(*pc->ops->view)(pc,viewer);}
1756:     if (pc->mat) {MatView(pc->mat,viewer);}
1757:     if (pc->pmat && pc->pmat != pc->mat) {MatView(pc->pmat,viewer);}
1758:   } else if (isbinary) {
1759:     PetscInt    classid = PC_FILE_CLASSID;
1760:     MPI_Comm    comm;
1761:     PetscMPIInt rank;
1762:     char        type[256];

1764:     PetscObjectGetComm((PetscObject)pc,&comm);
1765:     MPI_Comm_rank(comm,&rank);
1766:     if (!rank) {
1767:       PetscViewerBinaryWrite(viewer,&classid,1,PETSC_INT);
1768:       PetscStrncpy(type,((PetscObject)pc)->type_name,256);
1769:       PetscViewerBinaryWrite(viewer,type,256,PETSC_CHAR);
1770:     }
1771:     if (pc->ops->view) {
1772:       (*pc->ops->view)(pc,viewer);
1773:     }
1774:   } else if (isdraw) {
1775:     PetscDraw draw;
1776:     char      str[25];
1777:     PetscReal x,y,bottom,h;
1778:     PetscInt  n;

1780:     PetscViewerDrawGetDraw(viewer,0,&draw);
1781:     PetscDrawGetCurrentPoint(draw,&x,&y);
1782:     if (pc->mat) {
1783:       MatGetSize(pc->mat,&n,NULL);
1784:       PetscSNPrintf(str,25,"PC: %s (%D)",((PetscObject)pc)->type_name,n);
1785:     } else {
1786:       PetscSNPrintf(str,25,"PC: %s",((PetscObject)pc)->type_name);
1787:     }
1788:     PetscDrawStringBoxed(draw,x,y,PETSC_DRAW_RED,PETSC_DRAW_BLACK,str,NULL,&h);
1789:     bottom = y - h;
1790:     PetscDrawPushCurrentPoint(draw,x,bottom);
1791:     if (pc->ops->view) {
1792:       (*pc->ops->view)(pc,viewer);
1793:     }
1794:     PetscDrawPopCurrentPoint(draw);
1795: #if defined(PETSC_HAVE_SAWS)
1796:   } else if (issaws) {
1797:     PetscMPIInt rank;

1799:     PetscObjectName((PetscObject)pc);
1800:     MPI_Comm_rank(PETSC_COMM_WORLD,&rank);
1801:     if (!((PetscObject)pc)->amsmem && !rank) {
1802:       PetscObjectViewSAWs((PetscObject)pc,viewer);
1803:     }
1804:     if (pc->mat) {MatView(pc->mat,viewer);}
1805:     if (pc->pmat && pc->pmat != pc->mat) {MatView(pc->pmat,viewer);}
1806: #endif
1807:   }
1808:   return(0);
1809: }

1811: /*@C
1812:   PCRegister -  Adds a method to the preconditioner package.

1814:    Not collective

1816:    Input Parameters:
1817: +  name_solver - name of a new user-defined solver
1818: -  routine_create - routine to create method context

1820:    Notes:
1821:    PCRegister() may be called multiple times to add several user-defined preconditioners.

1823:    Sample usage:
1824: .vb
1825:    PCRegister("my_solver", MySolverCreate);
1826: .ve

1828:    Then, your solver can be chosen with the procedural interface via
1829: $     PCSetType(pc,"my_solver")
1830:    or at runtime via the option
1831: $     -pc_type my_solver

1833:    Level: advanced

1835: .seealso: PCRegisterAll()
1836: @*/
1837: PetscErrorCode  PCRegister(const char sname[],PetscErrorCode (*function)(PC))
1838: {

1842:   PCInitializePackage();
1843:   PetscFunctionListAdd(&PCList,sname,function);
1844:   return(0);
1845: }

1847: static PetscErrorCode MatMult_PC(Mat A,Vec X,Vec Y)
1848: {
1849:   PC             pc;

1853:   MatShellGetContext(A,&pc);
1854:   PCApply(pc,X,Y);
1855:   return(0);
1856: }

1858: /*@
1859:     PCComputeOperator - Computes the explicit preconditioned operator.

1861:     Collective on PC

1863:     Input Parameter:
1864: +   pc - the preconditioner object
1865: -   mattype - the matrix type to be used for the operator

1867:     Output Parameter:
1868: .   mat - the explict preconditioned operator

1870:     Notes:
1871:     This computation is done by applying the operators to columns of the identity matrix.
1872:     This routine is costly in general, and is recommended for use only with relatively small systems.
1873:     Currently, this routine uses a dense matrix format when mattype == NULL

1875:     Level: advanced

1877: .seealso: KSPComputeOperator(), MatType

1879: @*/
1880: PetscErrorCode  PCComputeOperator(PC pc,MatType mattype,Mat *mat)
1881: {
1883:   PetscInt       N,M,m,n;
1884:   Mat            A,Apc;

1889:   PCGetOperators(pc,&A,NULL);
1890:   MatGetLocalSize(A,&m,&n);
1891:   MatGetSize(A,&M,&N);
1892:   MatCreateShell(PetscObjectComm((PetscObject)pc),m,n,M,N,pc,&Apc);
1893:   MatShellSetOperation(Apc,MATOP_MULT,(void (*)(void))MatMult_PC);
1894:   MatComputeOperator(Apc,mattype,mat);
1895:   MatDestroy(&Apc);
1896:   return(0);
1897: }

1899: /*@
1900:    PCSetCoordinates - sets the coordinates of all the nodes on the local process

1902:    Collective on PC

1904:    Input Parameters:
1905: +  pc - the solver context
1906: .  dim - the dimension of the coordinates 1, 2, or 3
1907: .  nloc - the blocked size of the coordinates array
1908: -  coords - the coordinates array

1910:    Level: intermediate

1912:    Notes:
1913:    coords is an array of the dim coordinates for the nodes on
1914:    the local processor, of size dim*nloc.
1915:    If there are 108 equation on a processor
1916:    for a displacement finite element discretization of elasticity (so
1917:    that there are nloc = 36 = 108/3 nodes) then the array must have 108
1918:    double precision values (ie, 3 * 36).  These x y z coordinates
1919:    should be ordered for nodes 0 to N-1 like so: [ 0.x, 0.y, 0.z, 1.x,
1920:    ... , N-1.z ].

1922: .seealso: MatSetNearNullSpace()
1923: @*/
1924: PetscErrorCode PCSetCoordinates(PC pc, PetscInt dim, PetscInt nloc, PetscReal coords[])
1925: {

1931:   PetscTryMethod(pc,"PCSetCoordinates_C",(PC,PetscInt,PetscInt,PetscReal*),(pc,dim,nloc,coords));
1932:   return(0);
1933: }

1935: /*@
1936:    PCGetInterpolations - Gets interpolation matrices for all levels (except level 0)

1938:    Logically Collective on PC

1940:    Input Parameters:
1941: +  pc - the precondition context

1943:    Output Parameter:
1944: -  num_levels - the number of levels
1945: .  interpolations - the interpolation matrices (size of num_levels-1)

1947:    Level: advanced

1949: .keywords: MG, GAMG, BoomerAMG, multigrid, interpolation, level

1951: .seealso: PCMGGetRestriction(), PCMGSetInterpolation(), PCMGGetInterpolation(), PCGetCoarseOperators()
1952: @*/
1953: PetscErrorCode PCGetInterpolations(PC pc,PetscInt *num_levels,Mat *interpolations[])
1954: {

1961:   PetscUseMethod(pc,"PCGetInterpolations_C",(PC,PetscInt*,Mat*[]),(pc,num_levels,interpolations));
1962:   return(0);
1963: }

1965: /*@
1966:    PCGetCoarseOperators - Gets coarse operator matrices for all levels (except the finest level)

1968:    Logically Collective on PC

1970:    Input Parameters:
1971: +  pc - the precondition context

1973:    Output Parameter:
1974: -  num_levels - the number of levels
1975: .  coarseOperators - the coarse operator matrices (size of num_levels-1)

1977:    Level: advanced

1979: .keywords: MG, GAMG, BoomerAMG, get, multigrid, interpolation, level

1981: .seealso: PCMGGetRestriction(), PCMGSetInterpolation(), PCMGGetRScale(), PCMGGetInterpolation(), PCGetInterpolations()
1982: @*/
1983: PetscErrorCode PCGetCoarseOperators(PC pc,PetscInt *num_levels,Mat *coarseOperators[])
1984: {

1991:   PetscUseMethod(pc,"PCGetCoarseOperators_C",(PC,PetscInt*,Mat*[]),(pc,num_levels,coarseOperators));
1992:   return(0);
1993: }