Actual source code: precon.c

petsc-3.6.1 2015-07-22
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  2: /*
  3:     The PC (preconditioner) interface routines, callable by users.
  4: */
  5: #include <petsc/private/pcimpl.h>            /*I "petscksp.h" I*/
  6: #include <petscdm.h>

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

 15: PetscErrorCode PCGetDefaultType_Private(PC pc,const char *type[])
 16: {
 18:   PetscMPIInt    size;
 19:   PetscBool      flg1,flg2,set,flg3;

 22:   MPI_Comm_size(PetscObjectComm((PetscObject)pc),&size);
 23:   if (pc->pmat) {
 24:     PetscErrorCode (*f)(Mat,MatReuse,Mat*);
 25:     PetscObjectQueryFunction((PetscObject)pc->pmat,"MatGetDiagonalBlock_C",&f);
 26:     if (size == 1) {
 27:       MatGetFactorAvailable(pc->pmat,"petsc",MAT_FACTOR_ICC,&flg1);
 28:       MatGetFactorAvailable(pc->pmat,"petsc",MAT_FACTOR_ILU,&flg2);
 29:       MatIsSymmetricKnown(pc->pmat,&set,&flg3);
 30:       if (flg1 && (!flg2 || (set && flg3))) {
 31:         *type = PCICC;
 32:       } else if (flg2) {
 33:         *type = PCILU;
 34:       } else if (f) { /* likely is a parallel matrix run on one processor */
 35:         *type = PCBJACOBI;
 36:       } else {
 37:         *type = PCNONE;
 38:       }
 39:     } else {
 40:        if (f) {
 41:         *type = PCBJACOBI;
 42:       } else {
 43:         *type = PCNONE;
 44:       }
 45:     }
 46:   } else {
 47:     if (size == 1) {
 48:       *type = PCILU;
 49:     } else {
 50:       *type = PCBJACOBI;
 51:     }
 52:   }
 53:   return(0);
 54: }

 58: /*@
 59:    PCReset - Resets a PC context to the pcsetupcalled = 0 state and removes any allocated Vecs and Mats

 61:    Collective on PC

 63:    Input Parameter:
 64: .  pc - the preconditioner context

 66:    Level: developer

 68:    Notes: 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

 70: .keywords: PC, destroy

 72: .seealso: PCCreate(), PCSetUp()
 73: @*/
 74: PetscErrorCode  PCReset(PC pc)
 75: {

 80:   if (pc->ops->reset) {
 81:     (*pc->ops->reset)(pc);
 82:   }
 83:   VecDestroy(&pc->diagonalscaleright);
 84:   VecDestroy(&pc->diagonalscaleleft);
 85:   MatDestroy(&pc->pmat);
 86:   MatDestroy(&pc->mat);

 88:   pc->setupcalled = 0;
 89:   return(0);
 90: }

 94: /*@
 95:    PCDestroy - Destroys PC context that was created with PCCreate().

 97:    Collective on PC

 99:    Input Parameter:
100: .  pc - the preconditioner context

102:    Level: developer

104: .keywords: PC, destroy

106: .seealso: PCCreate(), PCSetUp()
107: @*/
108: PetscErrorCode  PCDestroy(PC *pc)
109: {

113:   if (!*pc) return(0);
115:   if (--((PetscObject)(*pc))->refct > 0) {*pc = 0; return(0);}

117:   PCReset(*pc);

119:   /* if memory was published with SAWs then destroy it */
120:   PetscObjectSAWsViewOff((PetscObject)*pc);
121:   if ((*pc)->ops->destroy) {(*(*pc)->ops->destroy)((*pc));}
122:   DMDestroy(&(*pc)->dm);
123:   PetscHeaderDestroy(pc);
124:   return(0);
125: }

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

133:    Logically Collective on PC

135:    Input Parameter:
136: .  pc - the preconditioner context

138:    Output Parameter:
139: .  flag - PETSC_TRUE if it applies the scaling

141:    Level: developer

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

147: .keywords: PC

149: .seealso: PCCreate(), PCSetUp(), PCDiagonalScaleLeft(), PCDiagonalScaleRight(), PCSetDiagonalScale()
150: @*/
151: PetscErrorCode  PCGetDiagonalScale(PC pc,PetscBool  *flag)
152: {
156:   *flag = pc->diagonalscale;
157:   return(0);
158: }

162: /*@
163:    PCSetDiagonalScale - Indicates the left scaling to use to apply an additional left and right
164:       scaling as needed by certain time-stepping codes.

166:    Logically Collective on PC

168:    Input Parameters:
169: +  pc - the preconditioner context
170: -  s - scaling vector

172:    Level: intermediate

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

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

180: .keywords: PC

182: .seealso: PCCreate(), PCSetUp(), PCDiagonalScaleLeft(), PCDiagonalScaleRight(), PCGetDiagonalScale()
183: @*/
184: PetscErrorCode  PCSetDiagonalScale(PC pc,Vec s)
185: {

191:   pc->diagonalscale     = PETSC_TRUE;

193:   PetscObjectReference((PetscObject)s);
194:   VecDestroy(&pc->diagonalscaleleft);

196:   pc->diagonalscaleleft = s;

198:   VecDuplicate(s,&pc->diagonalscaleright);
199:   VecCopy(s,pc->diagonalscaleright);
200:   VecReciprocal(pc->diagonalscaleright);
201:   return(0);
202: }

206: /*@
207:    PCDiagonalScaleLeft - Scales a vector by the left scaling as needed by certain time-stepping codes.

209:    Logically Collective on PC

211:    Input Parameters:
212: +  pc - the preconditioner context
213: .  in - input vector
214: +  out - scaled vector (maybe the same as in)

216:    Level: intermediate

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

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

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

226: .keywords: PC

228: .seealso: PCCreate(), PCSetUp(), PCDiagonalScaleSet(), PCDiagonalScaleRight(), PCDiagonalScale()
229: @*/
230: PetscErrorCode  PCDiagonalScaleLeft(PC pc,Vec in,Vec out)
231: {

238:   if (pc->diagonalscale) {
239:     VecPointwiseMult(out,pc->diagonalscaleleft,in);
240:   } else if (in != out) {
241:     VecCopy(in,out);
242:   }
243:   return(0);
244: }

248: /*@
249:    PCDiagonalScaleRight - Scales a vector by the right scaling as needed by certain time-stepping codes.

251:    Logically Collective on PC

253:    Input Parameters:
254: +  pc - the preconditioner context
255: .  in - input vector
256: +  out - scaled vector (maybe the same as in)

258:    Level: intermediate

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

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

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

268: .keywords: PC

270: .seealso: PCCreate(), PCSetUp(), PCDiagonalScaleLeft(), PCDiagonalScaleSet(), PCDiagonalScale()
271: @*/
272: PetscErrorCode  PCDiagonalScaleRight(PC pc,Vec in,Vec out)
273: {

280:   if (pc->diagonalscale) {
281:     VecPointwiseMult(out,pc->diagonalscaleright,in);
282:   } else if (in != out) {
283:     VecCopy(in,out);
284:   }
285:   return(0);
286: }

290: /*@
291:    PCSetUseAmat - Sets a flag to indicate that when the preconditioner needs to apply (part of) the
292:    operator during the preconditioning process it applies the Amat provided to TSSetRHSJacobian(), 
293:    TSSetIJacobian(), SNESSetJacobian(), KSPSetOperator() or PCSetOperator() not the Pmat.

295:    Logically Collective on PC

297:    Input Parameters:
298: +  pc - the preconditioner context
299: -  flg - PETSC_TRUE to use the Amat, PETSC_FALSE to use the Pmat (default is false)

301:    Options Database Key:
302: .  -pc_use_amat <true,false>

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

308:    Level: intermediate

310: .seealso: PCGetUseAmat(), PCBJACOBI, PGMG, PCFIELDSPLIT, PCCOMPOSITE
311: @*/
312: PetscErrorCode  PCSetUseAmat(PC pc,PetscBool flg)
313: {
316:   pc->useAmat = flg;
317:   return(0);
318: }

322: /*@
323:    PCSetErrorIfFailure - Causes PC to generate an error if a FPE, for example a zero pivot, is detected.

325:    Logically Collective on PC

327:    Input Parameters:
328: +  pc - iterative context obtained from PCCreate()
329: -  flg - PETSC_TRUE indicates you want the error generated

331:    Level: advanced

333:    Notes:
334:     Normally PETSc continues if a linear solver fails due to a failed setup of a preconditioner, you can call KSPGetConvergedReason() after a KSPSolve()
335:     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 
336:     detected.

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

340: .keywords: PC, set, initial guess, nonzero

342: .seealso: PCGetInitialGuessNonzero(), PCSetInitialGuessKnoll(), PCGetInitialGuessKnoll()
343: @*/
344: PetscErrorCode  PCSetErrorIfFailure(PC pc,PetscBool flg)
345: {
349:   pc->erroriffailure = flg;
350:   return(0);
351: }

355: /*@
356:    PCGetUseAmat - Gets a flag to indicate that when the preconditioner needs to apply (part of) the
357:    operator during the preconditioning process it applies the Amat provided to TSSetRHSJacobian(),
358:    TSSetIJacobian(), SNESSetJacobian(), KSPSetOperator() or PCSetOperator() not the Pmat.

360:    Logically Collective on PC

362:    Input Parameter:
363: .  pc - the preconditioner context

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

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

372:    Level: intermediate

374: .seealso: PCSetUseAmat(), PCBJACOBI, PGMG, PCFIELDSPLIT, PCCOMPOSITE
375: @*/
376: PetscErrorCode  PCGetUseAmat(PC pc,PetscBool *flg)
377: {
380:   *flg = pc->useAmat;
381:   return(0);
382: }

386: /*@
387:    PCCreate - Creates a preconditioner context.

389:    Collective on MPI_Comm

391:    Input Parameter:
392: .  comm - MPI communicator

394:    Output Parameter:
395: .  pc - location to put the preconditioner context

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

401:    Level: developer

403: .keywords: PC, create, context

405: .seealso: PCSetUp(), PCApply(), PCDestroy()
406: @*/
407: PetscErrorCode  PCCreate(MPI_Comm comm,PC *newpc)
408: {
409:   PC             pc;

414:   *newpc = 0;
415:   PCInitializePackage();

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

419:   pc->mat                  = 0;
420:   pc->pmat                 = 0;
421:   pc->setupcalled          = 0;
422:   pc->setfromoptionscalled = 0;
423:   pc->data                 = 0;
424:   pc->diagonalscale        = PETSC_FALSE;
425:   pc->diagonalscaleleft    = 0;
426:   pc->diagonalscaleright   = 0;

428:   pc->modifysubmatrices  = 0;
429:   pc->modifysubmatricesP = 0;

431:   *newpc = pc;
432:   return(0);

434: }

436: /* -------------------------------------------------------------------------------*/

440: /*@
441:    PCApply - Applies the preconditioner to a vector.

443:    Collective on PC and Vec

445:    Input Parameters:
446: +  pc - the preconditioner context
447: -  x - input vector

449:    Output Parameter:
450: .  y - output vector

452:    Level: developer

454: .keywords: PC, apply

456: .seealso: PCApplyTranspose(), PCApplyBAorAB()
457: @*/
458: PetscErrorCode  PCApply(PC pc,Vec x,Vec y)
459: {
461:   PetscInt       m,n,mv,nv;

467:   if (x == y) SETERRQ(PetscObjectComm((PetscObject)pc),PETSC_ERR_ARG_IDN,"x and y must be different vectors");
468:   if (pc->erroriffailure) {VecValidValues(x,2,PETSC_TRUE);}
469:   MatGetLocalSize(pc->mat,&m,&n);
470:   VecGetLocalSize(x,&nv);
471:   VecGetLocalSize(y,&mv);
472:   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);
473:   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);
474:   VecLocked(y,3);

476:   if (pc->setupcalled < 2) {
477:     PCSetUp(pc);
478:   }
479:   if (!pc->ops->apply) SETERRQ(PetscObjectComm((PetscObject)pc),PETSC_ERR_SUP,"PC does not have apply");
480:   VecLockPush(x);
481:   PetscLogEventBegin(PC_Apply,pc,x,y,0);
482:   (*pc->ops->apply)(pc,x,y);
483:   PetscLogEventEnd(PC_Apply,pc,x,y,0);
484:   if (pc->erroriffailure) {VecValidValues(y,3,PETSC_FALSE);}
485:   VecLockPop(x);
486:   return(0);
487: }

491: /*@
492:    PCApplySymmetricLeft - Applies the left part of a symmetric preconditioner to a vector.

494:    Collective on PC and Vec

496:    Input Parameters:
497: +  pc - the preconditioner context
498: -  x - input vector

500:    Output Parameter:
501: .  y - output vector

503:    Notes:
504:    Currently, this routine is implemented only for PCICC and PCJACOBI preconditioners.

506:    Level: developer

508: .keywords: PC, apply, symmetric, left

510: .seealso: PCApply(), PCApplySymmetricRight()
511: @*/
512: PetscErrorCode  PCApplySymmetricLeft(PC pc,Vec x,Vec y)
513: {

520:   if (x == y) SETERRQ(PetscObjectComm((PetscObject)pc),PETSC_ERR_ARG_IDN,"x and y must be different vectors");
521:   if (pc->erroriffailure) {VecValidValues(x,2,PETSC_TRUE);}
522:   if (pc->setupcalled < 2) {
523:     PCSetUp(pc);
524:   }
525:   if (!pc->ops->applysymmetricleft) SETERRQ(PetscObjectComm((PetscObject)pc),PETSC_ERR_SUP,"PC does not have left symmetric apply");
526:   VecLockPush(x);
527:   PetscLogEventBegin(PC_ApplySymmetricLeft,pc,x,y,0);
528:   (*pc->ops->applysymmetricleft)(pc,x,y);
529:   PetscLogEventEnd(PC_ApplySymmetricLeft,pc,x,y,0);
530:   VecLockPop(x);
531:   if (pc->erroriffailure) {VecValidValues(y,3,PETSC_FALSE);}
532:   return(0);
533: }

537: /*@
538:    PCApplySymmetricRight - Applies the right part of a symmetric preconditioner to a vector.

540:    Collective on PC and Vec

542:    Input Parameters:
543: +  pc - the preconditioner context
544: -  x - input vector

546:    Output Parameter:
547: .  y - output vector

549:    Level: developer

551:    Notes:
552:    Currently, this routine is implemented only for PCICC and PCJACOBI preconditioners.

554: .keywords: PC, apply, symmetric, right

556: .seealso: PCApply(), PCApplySymmetricLeft()
557: @*/
558: PetscErrorCode  PCApplySymmetricRight(PC pc,Vec x,Vec y)
559: {

566:   if (x == y) SETERRQ(PetscObjectComm((PetscObject)pc),PETSC_ERR_ARG_IDN,"x and y must be different vectors");
567:   if (pc->erroriffailure) {VecValidValues(x,2,PETSC_TRUE);}
568:   if (pc->setupcalled < 2) {
569:     PCSetUp(pc);
570:   }
571:   if (!pc->ops->applysymmetricright) SETERRQ(PetscObjectComm((PetscObject)pc),PETSC_ERR_SUP,"PC does not have left symmetric apply");
572:   VecLockPush(x);
573:   PetscLogEventBegin(PC_ApplySymmetricRight,pc,x,y,0);
574:   (*pc->ops->applysymmetricright)(pc,x,y);
575:   PetscLogEventEnd(PC_ApplySymmetricRight,pc,x,y,0);
576:   VecLockPop(x);
577:   if (pc->erroriffailure) {VecValidValues(y,3,PETSC_FALSE);}
578:   return(0);
579: }

583: /*@
584:    PCApplyTranspose - Applies the transpose of preconditioner to a vector.

586:    Collective on PC and Vec

588:    Input Parameters:
589: +  pc - the preconditioner context
590: -  x - input vector

592:    Output Parameter:
593: .  y - output vector

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

597:    Developer Notes: We need to implement a PCApplyHermitianTranspose()

599:    Level: developer

601: .keywords: PC, apply, transpose

603: .seealso: PCApply(), PCApplyBAorAB(), PCApplyBAorABTranspose(), PCApplyTransposeExists()
604: @*/
605: PetscErrorCode  PCApplyTranspose(PC pc,Vec x,Vec y)
606: {

613:   if (x == y) SETERRQ(PetscObjectComm((PetscObject)pc),PETSC_ERR_ARG_IDN,"x and y must be different vectors");
614:   if (pc->erroriffailure) {VecValidValues(x,2,PETSC_TRUE);}
615:   if (pc->setupcalled < 2) {
616:     PCSetUp(pc);
617:   }
618:   if (!pc->ops->applytranspose) SETERRQ(PetscObjectComm((PetscObject)pc),PETSC_ERR_SUP,"PC does not have apply transpose");
619:   VecLockPush(x);
620:   PetscLogEventBegin(PC_Apply,pc,x,y,0);
621:   (*pc->ops->applytranspose)(pc,x,y);
622:   PetscLogEventEnd(PC_Apply,pc,x,y,0);
623:   VecLockPop(x);
624:   if (pc->erroriffailure) {VecValidValues(y,3,PETSC_FALSE);}
625:   return(0);
626: }

630: /*@
631:    PCApplyTransposeExists - Test whether the preconditioner has a transpose apply operation

633:    Collective on PC and Vec

635:    Input Parameters:
636: .  pc - the preconditioner context

638:    Output Parameter:
639: .  flg - PETSC_TRUE if a transpose operation is defined

641:    Level: developer

643: .keywords: PC, apply, transpose

645: .seealso: PCApplyTranspose()
646: @*/
647: PetscErrorCode  PCApplyTransposeExists(PC pc,PetscBool  *flg)
648: {
652:   if (pc->ops->applytranspose) *flg = PETSC_TRUE;
653:   else *flg = PETSC_FALSE;
654:   return(0);
655: }

659: /*@
660:    PCApplyBAorAB - Applies the preconditioner and operator to a vector. y = B*A*x or y = A*B*x.

662:    Collective on PC and Vec

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

670:    Output Parameter:
671: .  y - output vector

673:    Level: developer

675:    Notes: 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
676:    specific KSPSolve() method must also be written to handle the post-solve "correction" for the diagonal scaling.

678: .keywords: PC, apply, operator

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

691:   if (x == y) SETERRQ(PetscObjectComm((PetscObject)pc),PETSC_ERR_ARG_IDN,"x and y must be different vectors");
692:   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");
693:   if (pc->diagonalscale && side == PC_SYMMETRIC) SETERRQ(PetscObjectComm((PetscObject)pc),PETSC_ERR_SUP,"Cannot include diagonal scaling with symmetric preconditioner application");
694:   if (pc->erroriffailure) {VecValidValues(x,3,PETSC_TRUE);}

696:   if (pc->setupcalled < 2) {
697:     PCSetUp(pc);
698:   }

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

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 and Vec

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: 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
760:       defined by B'. This is why this has the funny form that it computes tr(B) * tr(A)

762:     Level: developer

764: .keywords: PC, apply, operator, transpose

766: .seealso: PCApply(), PCApplyTranspose(), PCApplyBAorAB()
767: @*/
768: PetscErrorCode  PCApplyBAorABTranspose(PC pc,PCSide side,Vec x,Vec y,Vec work)
769: {

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

786:   if (pc->setupcalled < 2) {
787:     PCSetUp(pc);
788:   }

790:   if (side == PC_RIGHT) {
791:     PCApplyTranspose(pc,x,work);
792:     MatMultTranspose(pc->mat,work,y);
793:   } else if (side == PC_LEFT) {
794:     MatMultTranspose(pc->mat,x,work);
795:     PCApplyTranspose(pc,work,y);
796:   }
797:   /* add support for PC_SYMMETRIC */
798:   if (pc->erroriffailure) {VecValidValues(y,4,PETSC_FALSE);}
799:   return(0);
800: }

802: /* -------------------------------------------------------------------------------*/

806: /*@
807:    PCApplyRichardsonExists - Determines whether a particular preconditioner has a
808:    built-in fast application of Richardson's method.

810:    Not Collective

812:    Input Parameter:
813: .  pc - the preconditioner

815:    Output Parameter:
816: .  exists - PETSC_TRUE or PETSC_FALSE

818:    Level: developer

820: .keywords: PC, apply, Richardson, exists

822: .seealso: PCApplyRichardson()
823: @*/
824: PetscErrorCode  PCApplyRichardsonExists(PC pc,PetscBool  *exists)
825: {
829:   if (pc->ops->applyrichardson) *exists = PETSC_TRUE;
830:   else *exists = PETSC_FALSE;
831:   return(0);
832: }

836: /*@
837:    PCApplyRichardson - Applies several steps of Richardson iteration with
838:    the particular preconditioner. This routine is usually used by the
839:    Krylov solvers and not the application code directly.

841:    Collective on PC

843:    Input Parameters:
844: +  pc  - the preconditioner context
845: .  b   - the right hand side
846: .  w   - one work vector
847: .  rtol - relative decrease in residual norm convergence criteria
848: .  abstol - absolute residual norm convergence criteria
849: .  dtol - divergence residual norm increase criteria
850: .  its - the number of iterations to apply.
851: -  guesszero - if the input x contains nonzero initial guess

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

858:    Notes:
859:    Most preconditioners do not support this function. Use the command
860:    PCApplyRichardsonExists() to determine if one does.

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

865:    Level: developer

867: .keywords: PC, apply, Richardson

869: .seealso: PCApplyRichardsonExists()
870: @*/
871: PetscErrorCode  PCApplyRichardson(PC pc,Vec b,Vec y,Vec w,PetscReal rtol,PetscReal abstol, PetscReal dtol,PetscInt its,PetscBool guesszero,PetscInt *outits,PCRichardsonConvergedReason *reason)
872: {

880:   if (b == y) SETERRQ(PetscObjectComm((PetscObject)pc),PETSC_ERR_ARG_IDN,"b and y must be different vectors");
881:   if (pc->setupcalled < 2) {
882:     PCSetUp(pc);
883:   }
884:   if (!pc->ops->applyrichardson) SETERRQ(PetscObjectComm((PetscObject)pc),PETSC_ERR_SUP,"PC does not have apply richardson");
885:   (*pc->ops->applyrichardson)(pc,b,y,w,rtol,abstol,dtol,its,guesszero,outits,reason);
886:   return(0);
887: }

891: /*@
892:    PCGetSetUpFailedReason - Gets the reason a PCSetUp() failed or 0 if it did not fail

894:    Logically Collective on PC

896:    Input Parameter:
897: .  pc - the preconditioner context

899:    Output Parameter:
900: .  reason - the reason it failed, currently only -1 

902:    Level: advanced

904: .keywords: PC, setup

906: .seealso: PCCreate(), PCApply(), PCDestroy()
907: @*/
908: PetscErrorCode  PCGetSetUpFailedReason(PC pc,PetscInt *reason)
909: {
911:   if (pc->setupcalled < 0) *reason = pc->setupcalled;
912:   else *reason = 0;
913:   return(0);
914: }


917: /*
918:       a setupcall of 0 indicates never setup,
919:                      1 indicates has been previously setup
920:                     -1 indicates a PCSetUp() was attempted and failed
921: */
924: /*@
925:    PCSetUp - Prepares for the use of a preconditioner.

927:    Collective on PC

929:    Input Parameter:
930: .  pc - the preconditioner context

932:    Level: developer

934: .keywords: PC, setup

936: .seealso: PCCreate(), PCApply(), PCDestroy()
937: @*/
938: PetscErrorCode  PCSetUp(PC pc)
939: {
940:   PetscErrorCode   ierr;
941:   const char       *def;
942:   PetscObjectState matstate, matnonzerostate;

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

948:   if (pc->setupcalled && pc->reusepreconditioner) {
949:     PetscInfo(pc,"Leaving PC with identical preconditioner since reuse preconditioner is set\n");
950:     return(0);
951:   }

953:   PetscObjectStateGet((PetscObject)pc->pmat,&matstate);
954:   MatGetNonzeroState(pc->pmat,&matnonzerostate);
955:   if (!pc->setupcalled) {
956:     PetscInfo(pc,"Setting up PC for first time\n");
957:     pc->flag        = DIFFERENT_NONZERO_PATTERN;
958:   } else if (matstate == pc->matstate) {
959:     PetscInfo(pc,"Leaving PC with identical preconditioner since operator is unchanged\n");
960:     return(0);
961:   } else {
962:     if (matnonzerostate > pc->matnonzerostate) {
963:        PetscInfo(pc,"Setting up PC with different nonzero pattern\n");
964:        pc->flag            = DIFFERENT_NONZERO_PATTERN;
965:     } else {
966:       PetscInfo(pc,"Setting up PC with same nonzero pattern\n");
967:       pc->flag            = SAME_NONZERO_PATTERN;
968:     }
969:   }
970:   pc->matstate        = matstate;
971:   pc->matnonzerostate = matnonzerostate;

973:   if (!((PetscObject)pc)->type_name) {
974:     PCGetDefaultType_Private(pc,&def);
975:     PCSetType(pc,def);
976:   }

978:   MatSetErrorIfFPE(pc->pmat,pc->erroriffailure);
979:   MatSetErrorIfFPE(pc->mat,pc->erroriffailure);
980:   PetscLogEventBegin(PC_SetUp,pc,0,0,0);
981:   if (pc->ops->setup) {
982:     (*pc->ops->setup)(pc);
983:   }
984:   PetscLogEventEnd(PC_SetUp,pc,0,0,0);
985:   if (!pc->setupcalled) pc->setupcalled = 1;
986:   return(0);
987: }

991: /*@
992:    PCSetUpOnBlocks - Sets up the preconditioner for each block in
993:    the block Jacobi, block Gauss-Seidel, and overlapping Schwarz
994:    methods.

996:    Collective on PC

998:    Input Parameters:
999: .  pc - the preconditioner context

1001:    Level: developer

1003: .keywords: PC, setup, blocks

1005: .seealso: PCCreate(), PCApply(), PCDestroy(), PCSetUp()
1006: @*/
1007: PetscErrorCode  PCSetUpOnBlocks(PC pc)
1008: {

1013:   if (!pc->ops->setuponblocks) return(0);
1014:   PetscLogEventBegin(PC_SetUpOnBlocks,pc,0,0,0);
1015:   (*pc->ops->setuponblocks)(pc);
1016:   PetscLogEventEnd(PC_SetUpOnBlocks,pc,0,0,0);
1017:   return(0);
1018: }

1022: /*@C
1023:    PCSetModifySubMatrices - Sets a user-defined routine for modifying the
1024:    submatrices that arise within certain subdomain-based preconditioners.
1025:    The basic submatrices are extracted from the preconditioner matrix as
1026:    usual; the user can then alter these (for example, to set different boundary
1027:    conditions for each submatrix) before they are used for the local solves.

1029:    Logically Collective on PC

1031:    Input Parameters:
1032: +  pc - the preconditioner context
1033: .  func - routine for modifying the submatrices
1034: -  ctx - optional user-defined context (may be null)

1036:    Calling sequence of func:
1037: $     func (PC pc,PetscInt nsub,IS *row,IS *col,Mat *submat,void *ctx);

1039: .  row - an array of index sets that contain the global row numbers
1040:          that comprise each local submatrix
1041: .  col - an array of index sets that contain the global column numbers
1042:          that comprise each local submatrix
1043: .  submat - array of local submatrices
1044: -  ctx - optional user-defined context for private data for the
1045:          user-defined func routine (may be null)

1047:    Notes:
1048:    PCSetModifySubMatrices() MUST be called before KSPSetUp() and
1049:    KSPSolve().

1051:    A routine set by PCSetModifySubMatrices() is currently called within
1052:    the block Jacobi (PCBJACOBI) and additive Schwarz (PCASM)
1053:    preconditioners.  All other preconditioners ignore this routine.

1055:    Level: advanced

1057: .keywords: PC, set, modify, submatrices

1059: .seealso: PCModifySubMatrices(), PCASMGetSubMatrices()
1060: @*/
1061: PetscErrorCode  PCSetModifySubMatrices(PC pc,PetscErrorCode (*func)(PC,PetscInt,const IS[],const IS[],Mat[],void*),void *ctx)
1062: {
1065:   pc->modifysubmatrices  = func;
1066:   pc->modifysubmatricesP = ctx;
1067:   return(0);
1068: }

1072: /*@C
1073:    PCModifySubMatrices - Calls an optional user-defined routine within
1074:    certain preconditioners if one has been set with PCSetModifySubMarices().

1076:    Collective on PC

1078:    Input Parameters:
1079: +  pc - the preconditioner context
1080: .  nsub - the number of local submatrices
1081: .  row - an array of index sets that contain the global row numbers
1082:          that comprise each local submatrix
1083: .  col - an array of index sets that contain the global column numbers
1084:          that comprise each local submatrix
1085: .  submat - array of local submatrices
1086: -  ctx - optional user-defined context for private data for the
1087:          user-defined routine (may be null)

1089:    Output Parameter:
1090: .  submat - array of local submatrices (the entries of which may
1091:             have been modified)

1093:    Notes:
1094:    The user should NOT generally call this routine, as it will
1095:    automatically be called within certain preconditioners (currently
1096:    block Jacobi, additive Schwarz) if set.

1098:    The basic submatrices are extracted from the preconditioner matrix
1099:    as usual; the user can then alter these (for example, to set different
1100:    boundary conditions for each submatrix) before they are used for the
1101:    local solves.

1103:    Level: developer

1105: .keywords: PC, modify, submatrices

1107: .seealso: PCSetModifySubMatrices()
1108: @*/
1109: PetscErrorCode  PCModifySubMatrices(PC pc,PetscInt nsub,const IS row[],const IS col[],Mat submat[],void *ctx)
1110: {

1115:   if (!pc->modifysubmatrices) return(0);
1116:   PetscLogEventBegin(PC_ModifySubMatrices,pc,0,0,0);
1117:   (*pc->modifysubmatrices)(pc,nsub,row,col,submat,ctx);
1118:   PetscLogEventEnd(PC_ModifySubMatrices,pc,0,0,0);
1119:   return(0);
1120: }

1124: /*@
1125:    PCSetOperators - Sets the matrix associated with the linear system and
1126:    a (possibly) different one associated with the preconditioner.

1128:    Logically Collective on PC and Mat

1130:    Input Parameters:
1131: +  pc - the preconditioner context
1132: .  Amat - the matrix that defines the linear system
1133: -  Pmat - the matrix to be used in constructing the preconditioner, usually the same as Amat.

1135:    Notes:
1136:     Passing a NULL for Amat or Pmat removes the matrix that is currently used.

1138:     If you wish to replace either Amat or Pmat but leave the other one untouched then
1139:     first call KSPGetOperators() to get the one you wish to keep, call PetscObjectReference()
1140:     on it and then pass it back in in your call to KSPSetOperators().

1142:    More Notes about Repeated Solution of Linear Systems:
1143:    PETSc does NOT reset the matrix entries of either Amat or Pmat
1144:    to zero after a linear solve; the user is completely responsible for
1145:    matrix assembly.  See the routine MatZeroEntries() if desiring to
1146:    zero all elements of a matrix.

1148:    Level: intermediate

1150: .keywords: PC, set, operators, matrix, linear system

1152: .seealso: PCGetOperators(), MatZeroEntries()
1153:  @*/
1154: PetscErrorCode  PCSetOperators(PC pc,Mat Amat,Mat Pmat)
1155: {
1156:   PetscErrorCode   ierr;
1157:   PetscInt         m1,n1,m2,n2;

1165:   if (pc->setupcalled && pc->mat && pc->pmat && Amat && Pmat) {
1166:     MatGetLocalSize(Amat,&m1,&n1);
1167:     MatGetLocalSize(pc->mat,&m2,&n2);
1168:     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);
1169:     MatGetLocalSize(Pmat,&m1,&n1);
1170:     MatGetLocalSize(pc->pmat,&m2,&n2);
1171:     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);
1172:   }

1174:   if (Pmat != pc->pmat) {
1175:     /* changing the operator that defines the preconditioner thus reneed to clear current states so new preconditioner is built */
1176:     pc->matnonzerostate = -1;
1177:     pc->matstate        = -1;
1178:   }

1180:   /* reference first in case the matrices are the same */
1181:   if (Amat) {PetscObjectReference((PetscObject)Amat);}
1182:   MatDestroy(&pc->mat);
1183:   if (Pmat) {PetscObjectReference((PetscObject)Pmat);}
1184:   MatDestroy(&pc->pmat);
1185:   pc->mat  = Amat;
1186:   pc->pmat = Pmat;
1187:   return(0);
1188: }

1192: /*@
1193:    PCSetReusePreconditioner - reuse the current preconditioner even if the operator in the preconditioner has changed.

1195:    Logically Collective on PC

1197:    Input Parameters:
1198: +  pc - the preconditioner context
1199: -  flag - PETSC_TRUE do not compute a new preconditioner, PETSC_FALSE do compute a new preconditioner

1201:     Level: intermediate

1203: .seealso: PCGetOperators(), MatZeroEntries(), PCGetReusePreconditioner(), KSPSetReusePreconditioner()
1204:  @*/
1205: PetscErrorCode  PCSetReusePreconditioner(PC pc,PetscBool flag)
1206: {
1209:   pc->reusepreconditioner = flag;
1210:   return(0);
1211: }

1215: /*@
1216:    PCGetReusePreconditioner - Determines if the PC reuses the current preconditioner even if the operator in the preconditioner has changed.

1218:    Not Collective

1220:    Input Parameter:
1221: .  pc - the preconditioner context

1223:    Output Parameter:
1224: .  flag - PETSC_TRUE do not compute a new preconditioner, PETSC_FALSE do compute a new preconditioner

1226:    Level: intermediate

1228: .seealso: PCGetOperators(), MatZeroEntries(), PCSetReusePreconditioner()
1229:  @*/
1230: PetscErrorCode  PCGetReusePreconditioner(PC pc,PetscBool *flag)
1231: {
1234:   *flag = pc->reusepreconditioner;
1235:   return(0);
1236: }

1240: /*@C
1241:    PCGetOperators - Gets the matrix associated with the linear system and
1242:    possibly a different one associated with the preconditioner.

1244:    Not collective, though parallel Mats are returned if the PC is parallel

1246:    Input Parameter:
1247: .  pc - the preconditioner context

1249:    Output Parameters:
1250: +  Amat - the matrix defining the linear system
1251: -  Pmat - the matrix from which the preconditioner is constructed, usually the same as Amat.

1253:    Level: intermediate

1255:    Notes: Does not increase the reference count of the matrices, so you should not destroy them

1257:    Alternative usage: If the operators have NOT been set with KSP/PCSetOperators() then the operators
1258:       are created in PC and returned to the user. In this case, if both operators
1259:       mat and pmat are requested, two DIFFERENT operators will be returned. If
1260:       only one is requested both operators in the PC will be the same (i.e. as
1261:       if one had called KSP/PCSetOperators() with the same argument for both Mats).
1262:       The user must set the sizes of the returned matrices and their type etc just
1263:       as if the user created them with MatCreate(). For example,

1265: $         KSP/PCGetOperators(ksp/pc,&Amat,NULL); is equivalent to
1266: $           set size, type, etc of Amat

1268: $         MatCreate(comm,&mat);
1269: $         KSP/PCSetOperators(ksp/pc,Amat,Amat);
1270: $         PetscObjectDereference((PetscObject)mat);
1271: $           set size, type, etc of Amat

1273:      and

1275: $         KSP/PCGetOperators(ksp/pc,&Amat,&Pmat); is equivalent to
1276: $           set size, type, etc of Amat and Pmat

1278: $         MatCreate(comm,&Amat);
1279: $         MatCreate(comm,&Pmat);
1280: $         KSP/PCSetOperators(ksp/pc,Amat,Pmat);
1281: $         PetscObjectDereference((PetscObject)Amat);
1282: $         PetscObjectDereference((PetscObject)Pmat);
1283: $           set size, type, etc of Amat and Pmat

1285:     The rational for this support is so that when creating a TS, SNES, or KSP the hierarchy
1286:     of underlying objects (i.e. SNES, KSP, PC, Mat) and their livespans can be completely
1287:     managed by the top most level object (i.e. the TS, SNES, or KSP). Another way to look
1288:     at this is when you create a SNES you do not NEED to create a KSP and attach it to
1289:     the SNES object (the SNES object manages it for you). Similarly when you create a KSP
1290:     you do not need to attach a PC to it (the KSP object manages the PC object for you).
1291:     Thus, why should YOU have to create the Mat and attach it to the SNES/KSP/PC, when
1292:     it can be created for you?


1295: .keywords: PC, get, operators, matrix, linear system

1297: .seealso: PCSetOperators(), KSPGetOperators(), KSPSetOperators(), PCGetOperatorsSet()
1298: @*/
1299: PetscErrorCode  PCGetOperators(PC pc,Mat *Amat,Mat *Pmat)
1300: {

1305:   if (Amat) {
1306:     if (!pc->mat) {
1307:       if (pc->pmat && !Pmat) {  /* Apmat has been set, but user did not request it, so use for Amat */
1308:         pc->mat = pc->pmat;
1309:         PetscObjectReference((PetscObject)pc->mat);
1310:       } else {                  /* both Amat and Pmat are empty */
1311:         MatCreate(PetscObjectComm((PetscObject)pc),&pc->mat);
1312:         if (!Pmat) { /* user did NOT request Pmat, so make same as Amat */
1313:           pc->pmat = pc->mat;
1314:           PetscObjectReference((PetscObject)pc->pmat);
1315:         }
1316:       }
1317:     }
1318:     *Amat = pc->mat;
1319:   }
1320:   if (Pmat) {
1321:     if (!pc->pmat) {
1322:       if (pc->mat && !Amat) {    /* Amat has been set but was not requested, so use for pmat */
1323:         pc->pmat = pc->mat;
1324:         PetscObjectReference((PetscObject)pc->pmat);
1325:       } else {
1326:         MatCreate(PetscObjectComm((PetscObject)pc),&pc->pmat);
1327:         if (!Amat) { /* user did NOT request Amat, so make same as Pmat */
1328:           pc->mat = pc->pmat;
1329:           PetscObjectReference((PetscObject)pc->mat);
1330:         }
1331:       }
1332:     }
1333:     *Pmat = pc->pmat;
1334:   }
1335:   return(0);
1336: }

1340: /*@C
1341:    PCGetOperatorsSet - Determines if the matrix associated with the linear system and
1342:    possibly a different one associated with the preconditioner have been set in the PC.

1344:    Not collective, though the results on all processes should be the same

1346:    Input Parameter:
1347: .  pc - the preconditioner context

1349:    Output Parameters:
1350: +  mat - the matrix associated with the linear system was set
1351: -  pmat - matrix associated with the preconditioner was set, usually the same

1353:    Level: intermediate

1355: .keywords: PC, get, operators, matrix, linear system

1357: .seealso: PCSetOperators(), KSPGetOperators(), KSPSetOperators(), PCGetOperators()
1358: @*/
1359: PetscErrorCode  PCGetOperatorsSet(PC pc,PetscBool  *mat,PetscBool  *pmat)
1360: {
1363:   if (mat) *mat = (pc->mat)  ? PETSC_TRUE : PETSC_FALSE;
1364:   if (pmat) *pmat = (pc->pmat) ? PETSC_TRUE : PETSC_FALSE;
1365:   return(0);
1366: }

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

1387: .keywords: PC, get, factored, matrix
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: }

1404: /*@C
1405:    PCSetOptionsPrefix - Sets the prefix used for searching for all
1406:    PC options in the database.

1408:    Logically Collective on PC

1410:    Input Parameters:
1411: +  pc - the preconditioner context
1412: -  prefix - the prefix string to prepend to all PC option requests

1414:    Notes:
1415:    A hyphen (-) must NOT be given at the beginning of the prefix name.
1416:    The first character of all runtime options is AUTOMATICALLY the
1417:    hyphen.

1419:    Level: advanced

1421: .keywords: PC, set, options, prefix, database

1423: .seealso: PCAppendOptionsPrefix(), PCGetOptionsPrefix()
1424: @*/
1425: PetscErrorCode  PCSetOptionsPrefix(PC pc,const char prefix[])
1426: {

1431:   PetscObjectSetOptionsPrefix((PetscObject)pc,prefix);
1432:   return(0);
1433: }

1437: /*@C
1438:    PCAppendOptionsPrefix - Appends to the prefix used for searching for all
1439:    PC options in the database.

1441:    Logically Collective on PC

1443:    Input Parameters:
1444: +  pc - the preconditioner context
1445: -  prefix - the prefix string to prepend to all PC option requests

1447:    Notes:
1448:    A hyphen (-) must NOT be given at the beginning of the prefix name.
1449:    The first character of all runtime options is AUTOMATICALLY the
1450:    hyphen.

1452:    Level: advanced

1454: .keywords: PC, append, options, prefix, database

1456: .seealso: PCSetOptionsPrefix(), PCGetOptionsPrefix()
1457: @*/
1458: PetscErrorCode  PCAppendOptionsPrefix(PC pc,const char prefix[])
1459: {

1464:   PetscObjectAppendOptionsPrefix((PetscObject)pc,prefix);
1465:   return(0);
1466: }

1470: /*@C
1471:    PCGetOptionsPrefix - Gets the prefix used for searching for all
1472:    PC options in the database.

1474:    Not Collective

1476:    Input Parameters:
1477: .  pc - the preconditioner context

1479:    Output Parameters:
1480: .  prefix - pointer to the prefix string used, is returned

1482:    Notes: On the fortran side, the user should pass in a string 'prifix' of
1483:    sufficient length to hold the prefix.

1485:    Level: advanced

1487: .keywords: PC, get, options, prefix, database

1489: .seealso: PCSetOptionsPrefix(), PCAppendOptionsPrefix()
1490: @*/
1491: PetscErrorCode  PCGetOptionsPrefix(PC pc,const char *prefix[])
1492: {

1498:   PetscObjectGetOptionsPrefix((PetscObject)pc,prefix);
1499:   return(0);
1500: }

1504: /*@
1505:    PCPreSolve - Optional pre-solve phase, intended for any
1506:    preconditioner-specific actions that must be performed before
1507:    the iterative solve itself.

1509:    Collective on PC

1511:    Input Parameters:
1512: +  pc - the preconditioner context
1513: -  ksp - the Krylov subspace context

1515:    Level: developer

1517:    Sample of Usage:
1518: .vb
1519:     PCPreSolve(pc,ksp);
1520:     KSPSolve(ksp,b,x);
1521:     PCPostSolve(pc,ksp);
1522: .ve

1524:    Notes:
1525:    The pre-solve phase is distinct from the PCSetUp() phase.

1527:    KSPSolve() calls this directly, so is rarely called by the user.

1529: .keywords: PC, pre-solve

1531: .seealso: PCPostSolve()
1532: @*/
1533: PetscErrorCode  PCPreSolve(PC pc,KSP ksp)
1534: {
1536:   Vec            x,rhs;

1541:   pc->presolvedone++;
1542:   if (pc->presolvedone > 2) SETERRQ(PetscObjectComm((PetscObject)pc),PETSC_ERR_SUP,"Cannot embed PCPreSolve() more than twice");
1543:   KSPGetSolution(ksp,&x);
1544:   KSPGetRhs(ksp,&rhs);

1546:   if (pc->ops->presolve) {
1547:     (*pc->ops->presolve)(pc,ksp,rhs,x);
1548:   }
1549:   return(0);
1550: }

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: .keywords: PC, post-solve

1579: .seealso: PCPreSolve(), KSPSolve()
1580: @*/
1581: PetscErrorCode  PCPostSolve(PC pc,KSP ksp)
1582: {
1584:   Vec            x,rhs;

1589:   pc->presolvedone--;
1590:   KSPGetSolution(ksp,&x);
1591:   KSPGetRhs(ksp,&rhs);
1592:   if (pc->ops->postsolve) {
1593:      (*pc->ops->postsolve)(pc,ksp,rhs,x);
1594:   }
1595:   return(0);
1596: }

1600: /*@C
1601:   PCLoad - Loads a PC that has been stored in binary  with PCView().

1603:   Collective on PetscViewer

1605:   Input Parameters:
1606: + newdm - the newly loaded PC, this needs to have been created with PCCreate() or
1607:            some related function before a call to PCLoad().
1608: - viewer - binary file viewer, obtained from PetscViewerBinaryOpen()

1610:    Level: intermediate

1612:   Notes:
1613:    The type is determined by the data in the file, any type set into the PC before this call is ignored.

1615:   Notes for advanced users:
1616:   Most users should not need to know the details of the binary storage
1617:   format, since PCLoad() and PCView() completely hide these details.
1618:   But for anyone who's interested, the standard binary matrix storage
1619:   format is
1620: .vb
1621:      has not yet been determined
1622: .ve

1624: .seealso: PetscViewerBinaryOpen(), PCView(), MatLoad(), VecLoad()
1625: @*/
1626: PetscErrorCode  PCLoad(PC newdm, PetscViewer viewer)
1627: {
1629:   PetscBool      isbinary;
1630:   PetscInt       classid;
1631:   char           type[256];

1636:   PetscObjectTypeCompare((PetscObject)viewer,PETSCVIEWERBINARY,&isbinary);
1637:   if (!isbinary) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_WRONG,"Invalid viewer; open viewer with PetscViewerBinaryOpen()");

1639:   PetscViewerBinaryRead(viewer,&classid,1,NULL,PETSC_INT);
1640:   if (classid != PC_FILE_CLASSID) SETERRQ(PetscObjectComm((PetscObject)newdm),PETSC_ERR_ARG_WRONG,"Not PC next in file");
1641:   PetscViewerBinaryRead(viewer,type,256,NULL,PETSC_CHAR);
1642:   PCSetType(newdm, type);
1643:   if (newdm->ops->load) {
1644:     (*newdm->ops->load)(newdm,viewer);
1645:   }
1646:   return(0);
1647: }

1649: #include <petscdraw.h>
1650: #if defined(PETSC_HAVE_SAWS)
1651: #include <petscviewersaws.h>
1652: #endif
1655: /*@C
1656:    PCView - Prints the PC data structure.

1658:    Collective on PC

1660:    Input Parameters:
1661: +  PC - the PC context
1662: -  viewer - optional visualization context

1664:    Note:
1665:    The available visualization contexts include
1666: +     PETSC_VIEWER_STDOUT_SELF - standard output (default)
1667: -     PETSC_VIEWER_STDOUT_WORLD - synchronized standard
1668:          output where only the first processor opens
1669:          the file.  All other processors send their
1670:          data to the first processor to print.

1672:    The user can open an alternative visualization contexts with
1673:    PetscViewerASCIIOpen() (output to a specified file).

1675:    Level: developer

1677: .keywords: PC, view

1679: .seealso: KSPView(), PetscViewerASCIIOpen()
1680: @*/
1681: PetscErrorCode  PCView(PC pc,PetscViewer viewer)
1682: {
1683:   PCType            cstr;
1684:   PetscErrorCode    ierr;
1685:   PetscBool         iascii,isstring,isbinary,isdraw;
1686:   PetscViewerFormat format;
1687: #if defined(PETSC_HAVE_SAWS)
1688:   PetscBool         issaws;
1689: #endif

1693:   if (!viewer) {
1694:     PetscViewerASCIIGetStdout(PetscObjectComm((PetscObject)pc),&viewer);
1695:   }

1699:   PetscObjectTypeCompare((PetscObject)viewer,PETSCVIEWERASCII,&iascii);
1700:   PetscObjectTypeCompare((PetscObject)viewer,PETSCVIEWERSTRING,&isstring);
1701:   PetscObjectTypeCompare((PetscObject)viewer,PETSCVIEWERBINARY,&isbinary);
1702:   PetscObjectTypeCompare((PetscObject)viewer,PETSCVIEWERDRAW,&isdraw);
1703: #if defined(PETSC_HAVE_SAWS)
1704:   PetscObjectTypeCompare((PetscObject)viewer,PETSCVIEWERSAWS,&issaws);
1705: #endif

1707:   if (iascii) {
1708:     PetscViewerGetFormat(viewer,&format);
1709:     PetscObjectPrintClassNamePrefixType((PetscObject)pc,viewer);
1710:     if (!pc->setupcalled) {
1711:       PetscViewerASCIIPrintf(viewer,"  PC has not been set up so information may be incomplete\n");
1712:     }
1713:     if (pc->ops->view) {
1714:       PetscViewerASCIIPushTab(viewer);
1715:       (*pc->ops->view)(pc,viewer);
1716:       PetscViewerASCIIPopTab(viewer);
1717:     }
1718:     if (pc->mat) {
1719:       PetscViewerPushFormat(viewer,PETSC_VIEWER_ASCII_INFO);
1720:       if (pc->pmat == pc->mat) {
1721:         PetscViewerASCIIPrintf(viewer,"  linear system matrix = precond matrix:\n");
1722:         PetscViewerASCIIPushTab(viewer);
1723:         MatView(pc->mat,viewer);
1724:         PetscViewerASCIIPopTab(viewer);
1725:       } else {
1726:         if (pc->pmat) {
1727:           PetscViewerASCIIPrintf(viewer,"  linear system matrix followed by preconditioner matrix:\n");
1728:         } else {
1729:           PetscViewerASCIIPrintf(viewer,"  linear system matrix:\n");
1730:         }
1731:         PetscViewerASCIIPushTab(viewer);
1732:         MatView(pc->mat,viewer);
1733:         if (pc->pmat) {MatView(pc->pmat,viewer);}
1734:         PetscViewerASCIIPopTab(viewer);
1735:       }
1736:       PetscViewerPopFormat(viewer);
1737:     }
1738:   } else if (isstring) {
1739:     PCGetType(pc,&cstr);
1740:     PetscViewerStringSPrintf(viewer," %-7.7s",cstr);
1741:     if (pc->ops->view) {(*pc->ops->view)(pc,viewer);}
1742:   } else if (isbinary) {
1743:     PetscInt    classid = PC_FILE_CLASSID;
1744:     MPI_Comm    comm;
1745:     PetscMPIInt rank;
1746:     char        type[256];

1748:     PetscObjectGetComm((PetscObject)pc,&comm);
1749:     MPI_Comm_rank(comm,&rank);
1750:     if (!rank) {
1751:       PetscViewerBinaryWrite(viewer,&classid,1,PETSC_INT,PETSC_FALSE);
1752:       PetscStrncpy(type,((PetscObject)pc)->type_name,256);
1753:       PetscViewerBinaryWrite(viewer,type,256,PETSC_CHAR,PETSC_FALSE);
1754:     }
1755:     if (pc->ops->view) {
1756:       (*pc->ops->view)(pc,viewer);
1757:     }
1758:   } else if (isdraw) {
1759:     PetscDraw draw;
1760:     char      str[25];
1761:     PetscReal x,y,bottom,h;
1762:     PetscInt  n;

1764:     PetscViewerDrawGetDraw(viewer,0,&draw);
1765:     PetscDrawGetCurrentPoint(draw,&x,&y);
1766:     if (pc->mat) {
1767:       MatGetSize(pc->mat,&n,NULL);
1768:       PetscSNPrintf(str,25,"PC: %s (%D)",((PetscObject)pc)->type_name,n);
1769:     } else {
1770:       PetscSNPrintf(str,25,"PC: %s",((PetscObject)pc)->type_name);
1771:     }
1772:     PetscDrawStringBoxed(draw,x,y,PETSC_DRAW_RED,PETSC_DRAW_BLACK,str,NULL,&h);
1773:     bottom = y - h;
1774:     PetscDrawPushCurrentPoint(draw,x,bottom);
1775:     if (pc->ops->view) {
1776:       (*pc->ops->view)(pc,viewer);
1777:     }
1778:     PetscDrawPopCurrentPoint(draw);
1779: #if defined(PETSC_HAVE_SAWS)
1780:   } else if (issaws) {
1781:     PetscMPIInt rank;

1783:     PetscObjectName((PetscObject)pc);
1784:     MPI_Comm_rank(PETSC_COMM_WORLD,&rank);
1785:     if (!((PetscObject)pc)->amsmem && !rank) {
1786:       PetscObjectViewSAWs((PetscObject)pc,viewer);
1787:     }
1788:     if (pc->mat) {MatView(pc->mat,viewer);}
1789:     if (pc->pmat && pc->pmat != pc->mat) {MatView(pc->pmat,viewer);}
1790: #endif
1791:   }
1792:   return(0);
1793: }


1798: /*@
1799:    PCSetInitialGuessNonzero - Tells the iterative solver that the
1800:    initial guess is nonzero; otherwise PC assumes the initial guess
1801:    is to be zero (and thus zeros it out before solving).

1803:    Logically Collective on PC

1805:    Input Parameters:
1806: +  pc - iterative context obtained from PCCreate()
1807: -  flg - PETSC_TRUE indicates the guess is non-zero, PETSC_FALSE indicates the guess is zero

1809:    Level: Developer

1811:    Notes:
1812:     This is a weird function. Since PC's are linear operators on the right hand side they
1813:     CANNOT use an initial guess. This function is for the "pass-through" preconditioners
1814:     PCKSP and PCREDUNDANT  and causes the inner KSP object to use the nonzero
1815:     initial guess. Not currently working for PCREDUNDANT, that has to be rewritten to use KSP.


1818: .keywords: PC, set, initial guess, nonzero

1820: .seealso: PCGetInitialGuessNonzero(), PCSetInitialGuessKnoll(), PCGetInitialGuessKnoll()
1821: @*/
1822: PetscErrorCode  PCSetInitialGuessNonzero(PC pc,PetscBool flg)
1823: {
1826:   pc->nonzero_guess = flg;
1827:   return(0);
1828: }

1832: /*@
1833:    PCGetInitialGuessNonzero - Determines if the iterative solver assumes that the
1834:    initial guess is nonzero; otherwise PC assumes the initial guess
1835:    is to be zero (and thus zeros it out before solving).

1837:    Logically Collective on PC

1839:    Input Parameter:
1840: .   pc - iterative context obtained from PCCreate()

1842:    Output Parameter:
1843: .  flg - PETSC_TRUE indicates the guess is non-zero, PETSC_FALSE indicates the guess is zero

1845:    Level: Developer

1847: .keywords: PC, set, initial guess, nonzero

1849: .seealso: PCGetInitialGuessNonzero(), PCSetInitialGuessKnoll(), PCGetInitialGuessKnoll(), PCSetInitialGuessNonzero()
1850: @*/
1851: PetscErrorCode  PCGetInitialGuessNonzero(PC pc,PetscBool *flg)
1852: {
1854:   *flg = pc->nonzero_guess;
1855:   return(0);
1856: }

1860: /*@C
1861:   PCRegister -  Adds a method to the preconditioner package.

1863:    Not collective

1865:    Input Parameters:
1866: +  name_solver - name of a new user-defined solver
1867: -  routine_create - routine to create method context

1869:    Notes:
1870:    PCRegister() may be called multiple times to add several user-defined preconditioners.

1872:    Sample usage:
1873: .vb
1874:    PCRegister("my_solver", MySolverCreate);
1875: .ve

1877:    Then, your solver can be chosen with the procedural interface via
1878: $     PCSetType(pc,"my_solver")
1879:    or at runtime via the option
1880: $     -pc_type my_solver

1882:    Level: advanced

1884: .keywords: PC, register

1886: .seealso: PCRegisterAll(), PCRegisterDestroy()
1887: @*/
1888: PetscErrorCode  PCRegister(const char sname[],PetscErrorCode (*function)(PC))
1889: {

1893:   PetscFunctionListAdd(&PCList,sname,function);
1894:   return(0);
1895: }

1899: /*@
1900:     PCComputeExplicitOperator - Computes the explicit preconditioned operator.

1902:     Collective on PC

1904:     Input Parameter:
1905: .   pc - the preconditioner object

1907:     Output Parameter:
1908: .   mat - the explict preconditioned operator

1910:     Notes:
1911:     This computation is done by applying the operators to columns of the
1912:     identity matrix.

1914:     Currently, this routine uses a dense matrix format when 1 processor
1915:     is used and a sparse format otherwise.  This routine is costly in general,
1916:     and is recommended for use only with relatively small systems.

1918:     Level: advanced

1920: .keywords: PC, compute, explicit, operator

1922: .seealso: KSPComputeExplicitOperator()

1924: @*/
1925: PetscErrorCode  PCComputeExplicitOperator(PC pc,Mat *mat)
1926: {
1927:   Vec            in,out;
1929:   PetscInt       i,M,m,*rows,start,end;
1930:   PetscMPIInt    size;
1931:   MPI_Comm       comm;
1932:   PetscScalar    *array,one = 1.0;


1938:   PetscObjectGetComm((PetscObject)pc,&comm);
1939:   MPI_Comm_size(comm,&size);

1941:   if (!pc->pmat) SETERRQ(PetscObjectComm((PetscObject)pc),PETSC_ERR_ORDER,"You must call KSPSetOperators() or PCSetOperators() before this call");
1942:   MatCreateVecs(pc->pmat,&in,0);
1943:   VecDuplicate(in,&out);
1944:   VecGetOwnershipRange(in,&start,&end);
1945:   VecGetSize(in,&M);
1946:   VecGetLocalSize(in,&m);
1947:   PetscMalloc1(m+1,&rows);
1948:   for (i=0; i<m; i++) rows[i] = start + i;

1950:   MatCreate(comm,mat);
1951:   MatSetSizes(*mat,m,m,M,M);
1952:   if (size == 1) {
1953:     MatSetType(*mat,MATSEQDENSE);
1954:     MatSeqDenseSetPreallocation(*mat,NULL);
1955:   } else {
1956:     MatSetType(*mat,MATMPIAIJ);
1957:     MatMPIAIJSetPreallocation(*mat,0,NULL,0,NULL);
1958:   }
1959:   MatSetOption(*mat,MAT_NEW_NONZERO_LOCATION_ERR,PETSC_FALSE);

1961:   for (i=0; i<M; i++) {

1963:     VecSet(in,0.0);
1964:     VecSetValues(in,1,&i,&one,INSERT_VALUES);
1965:     VecAssemblyBegin(in);
1966:     VecAssemblyEnd(in);

1968:     /* should fix, allowing user to choose side */
1969:     PCApply(pc,in,out);

1971:     VecGetArray(out,&array);
1972:     MatSetValues(*mat,m,rows,1,&i,array,INSERT_VALUES);
1973:     VecRestoreArray(out,&array);

1975:   }
1976:   PetscFree(rows);
1977:   VecDestroy(&out);
1978:   MatAssemblyBegin(*mat,MAT_FINAL_ASSEMBLY);
1979:   MatAssemblyEnd(*mat,MAT_FINAL_ASSEMBLY);
1980:   return(0);
1981: }

1985: /*@
1986:    PCSetCoordinates - sets the coordinates of all the nodes on the local process

1988:    Collective on PC

1990:    Input Parameters:
1991: +  pc - the solver context
1992: .  dim - the dimension of the coordinates 1, 2, or 3
1993: -  coords - the coordinates

1995:    Level: intermediate

1997:    Notes: coords is an array of the 3D coordinates for the nodes on
1998:    the local processor.  So if there are 108 equation on a processor
1999:    for a displacement finite element discretization of elasticity (so
2000:    that there are 36 = 108/3 nodes) then the array must have 108
2001:    double precision values (ie, 3 * 36).  These x y z coordinates
2002:    should be ordered for nodes 0 to N-1 like so: [ 0.x, 0.y, 0.z, 1.x,
2003:    ... , N-1.z ].

2005: .seealso: MatSetNearNullSpace
2006: @*/
2007: PetscErrorCode PCSetCoordinates(PC pc, PetscInt dim, PetscInt nloc, PetscReal *coords)
2008: {

2012:   PetscTryMethod(pc,"PCSetCoordinates_C",(PC,PetscInt,PetscInt,PetscReal*),(pc,dim,nloc,coords));
2013:   return(0);
2014: }