Actual source code: bjacobi.c

  1: #define PETSCKSP_DLL

  3: /*
  4:    Defines a block Jacobi preconditioner.
  5: */
 6:  #include private/matimpl.h
 7:  #include private/pcimpl.h
 8:  #include ../src/ksp/pc/impls/bjacobi/bjacobi.h

 10: static PetscErrorCode PCSetUp_BJacobi_Singleblock(PC,Mat,Mat);
 11: static PetscErrorCode PCSetUp_BJacobi_Multiblock(PC,Mat,Mat);

 15: static PetscErrorCode PCSetUp_BJacobi(PC pc)
 16: {
 17:   PC_BJacobi     *jac = (PC_BJacobi*)pc->data;
 18:   Mat            mat = pc->mat,pmat = pc->pmat;
 19:   PetscErrorCode ierr,(*f)(Mat,PetscTruth*,MatReuse,Mat*);
 20:   PetscInt       N,M,start,i,sum,end;
 21:   PetscInt       bs,i_start=-1,i_end=-1;
 22:   PetscMPIInt    rank,size;
 23:   const char     *pprefix,*mprefix;

 26:   MPI_Comm_rank(((PetscObject)pc)->comm,&rank);
 27:   MPI_Comm_size(((PetscObject)pc)->comm,&size);
 28:   MatGetLocalSize(pc->pmat,&M,&N);
 29:   MatGetBlockSize(pc->pmat,&bs);

 31:   /* ----------
 32:       Determines the number of blocks assigned to each processor 
 33:   */

 35:   /*   local block count  given */
 36:   if (jac->n_local > 0 && jac->n < 0) {
 37:     MPI_Allreduce(&jac->n_local,&jac->n,1,MPIU_INT,MPI_SUM,((PetscObject)pc)->comm);
 38:     if (jac->l_lens) { /* check that user set these correctly */
 39:       sum = 0;
 40:       for (i=0; i<jac->n_local; i++) {
 41:         if (jac->l_lens[i]/bs*bs !=jac->l_lens[i]) {
 42:           SETERRQ(PETSC_ERR_ARG_SIZ,"Mat blocksize doesn't match block Jacobi layout");
 43:         }
 44:         sum += jac->l_lens[i];
 45:       }
 46:       if (sum != M) SETERRQ(PETSC_ERR_ARG_SIZ,"Local lens sent incorrectly");
 47:     } else {
 48:       PetscMalloc(jac->n_local*sizeof(PetscInt),&jac->l_lens);
 49:       for (i=0; i<jac->n_local; i++) {
 50:         jac->l_lens[i] = bs*((M/bs)/jac->n_local + (((M/bs) % jac->n_local) > i));
 51:       }
 52:     }
 53:   } else if (jac->n > 0 && jac->n_local < 0) { /* global block count given */
 54:     /* global blocks given: determine which ones are local */
 55:     if (jac->g_lens) {
 56:       /* check if the g_lens is has valid entries */
 57:       for (i=0; i<jac->n; i++) {
 58:         if (!jac->g_lens[i]) SETERRQ(PETSC_ERR_ARG_SIZ,"Zero block not allowed");
 59:         if (jac->g_lens[i]/bs*bs != jac->g_lens[i]) {
 60:           SETERRQ(PETSC_ERR_ARG_SIZ,"Mat blocksize doesn't match block Jacobi layout");
 61:         }
 62:       }
 63:       if (size == 1) {
 64:         jac->n_local = jac->n;
 65:         PetscMalloc(jac->n_local*sizeof(PetscInt),&jac->l_lens);
 66:         PetscMemcpy(jac->l_lens,jac->g_lens,jac->n_local*sizeof(PetscInt));
 67:         /* check that user set these correctly */
 68:         sum = 0;
 69:         for (i=0; i<jac->n_local; i++) sum += jac->l_lens[i];
 70:         if (sum != M) SETERRQ(PETSC_ERR_ARG_SIZ,"Global lens sent incorrectly");
 71:       } else {
 72:         MatGetOwnershipRange(pc->pmat,&start,&end);
 73:         /* loop over blocks determing first one owned by me */
 74:         sum = 0;
 75:         for (i=0; i<jac->n+1; i++) {
 76:           if (sum == start) { i_start = i; goto start_1;}
 77:           if (i < jac->n) sum += jac->g_lens[i];
 78:         }
 79:         SETERRQ(PETSC_ERR_ARG_SIZ,"Block sizes\n\
 80:                    used in PCBJacobiSetTotalBlocks()\n\
 81:                    are not compatible with parallel matrix layout");
 82:  start_1:
 83:         for (i=i_start; i<jac->n+1; i++) {
 84:           if (sum == end) { i_end = i; goto end_1; }
 85:           if (i < jac->n) sum += jac->g_lens[i];
 86:         }
 87:         SETERRQ(PETSC_ERR_ARG_SIZ,"Block sizes\n\
 88:                       used in PCBJacobiSetTotalBlocks()\n\
 89:                       are not compatible with parallel matrix layout");
 90:  end_1:
 91:         jac->n_local = i_end - i_start;
 92:         PetscMalloc(jac->n_local*sizeof(PetscInt),&jac->l_lens);
 93:         PetscMemcpy(jac->l_lens,jac->g_lens+i_start,jac->n_local*sizeof(PetscInt));
 94:       }
 95:     } else { /* no global blocks given, determine then using default layout */
 96:       jac->n_local = jac->n/size + ((jac->n % size) > rank);
 97:       PetscMalloc(jac->n_local*sizeof(PetscInt),&jac->l_lens);
 98:       for (i=0; i<jac->n_local; i++) {
 99:         jac->l_lens[i] = ((M/bs)/jac->n_local + (((M/bs) % jac->n_local) > i))*bs;
100:         if (!jac->l_lens[i]) SETERRQ(PETSC_ERR_ARG_SIZ,"Too many blocks given");
101:       }
102:     }
103:   } else if (jac->n < 0 && jac->n_local < 0) { /* no blocks given */
104:     jac->n         = size;
105:     jac->n_local   = 1;
106:     PetscMalloc(sizeof(PetscInt),&jac->l_lens);
107:     jac->l_lens[0] = M;
108:   }
109:   if (jac->n_local < 1) SETERRQ(PETSC_ERR_ARG_OUTOFRANGE,"Number of blocks is less than number of processors");

111:   MPI_Comm_size(((PetscObject)pc)->comm,&size);
112:   PetscObjectQueryFunction((PetscObject)pc->mat,"MatGetDiagonalBlock_C",(void (**)(void))&f);
113:   if (size == 1 && !f) {
114:     mat  = pc->mat;
115:     pmat = pc->pmat;
116:   } else {
117:     PetscTruth iscopy;
118:     MatReuse   scall;

120:     if (jac->use_true_local) {
121:       scall = MAT_INITIAL_MATRIX;
122:       if (pc->setupcalled) {
123:         if (pc->flag == SAME_NONZERO_PATTERN) {
124:           if (jac->tp_mat) {
125:             scall = MAT_REUSE_MATRIX;
126:             mat   = jac->tp_mat;
127:           }
128:         } else {
129:           if (jac->tp_mat)  {
130:             MatDestroy(jac->tp_mat);
131:           }
132:         }
133:       }
134:       if (!f) {
135:         SETERRQ(PETSC_ERR_SUP,"This matrix does not support getting diagonal block");
136:       }
137:       (*f)(pc->mat,&iscopy,scall,&mat);
138:       /* make submatrix have same prefix as entire matrix */
139:       PetscObjectGetOptionsPrefix((PetscObject)pc->mat,&mprefix);
140:       PetscObjectSetOptionsPrefix((PetscObject)mat,mprefix);
141:       if (iscopy) {
142:         jac->tp_mat = mat;
143:       }
144:     }
145:     if (pc->pmat != pc->mat || !jac->use_true_local) {
146:       scall = MAT_INITIAL_MATRIX;
147:       if (pc->setupcalled) {
148:         if (pc->flag == SAME_NONZERO_PATTERN) {
149:           if (jac->tp_pmat) {
150:             scall = MAT_REUSE_MATRIX;
151:             pmat   = jac->tp_pmat;
152:           }
153:         } else {
154:           if (jac->tp_pmat)  {
155:             MatDestroy(jac->tp_pmat);
156:           }
157:         }
158:       }
159:       PetscObjectQueryFunction((PetscObject)pc->pmat,"MatGetDiagonalBlock_C",(void (**)(void))&f);
160:       if (!f) {
161:         const char *type;
162:         PetscObjectGetType((PetscObject) pc->pmat,&type);
163:         SETERRQ1(PETSC_ERR_SUP,"This matrix type, %s, does not support getting diagonal block", type);
164:       }
165:       (*f)(pc->pmat,&iscopy,scall,&pmat);
166:       /* make submatrix have same prefix as entire matrix */
167:       PetscObjectGetOptionsPrefix((PetscObject)pc->pmat,&pprefix);
168:       PetscObjectSetOptionsPrefix((PetscObject)pmat,pprefix);
169:       if (iscopy) {
170:         jac->tp_pmat = pmat;
171:       }
172:     } else {
173:       pmat = mat;
174:     }
175:   }

177:   /* ------
178:      Setup code depends on the number of blocks 
179:   */
180:   if (jac->n_local == 1) {
181:     PCSetUp_BJacobi_Singleblock(pc,mat,pmat);
182:   } else {
183:     PCSetUp_BJacobi_Multiblock(pc,mat,pmat);
184:   }
185:   return(0);
186: }

188: /* Default destroy, if it has never been setup */
191: static PetscErrorCode PCDestroy_BJacobi(PC pc)
192: {
193:   PC_BJacobi     *jac = (PC_BJacobi*)pc->data;

197:   PetscFree(jac->g_lens);
198:   PetscFree(jac->l_lens);
199:   PetscFree(jac);
200:   return(0);
201: }


206: static PetscErrorCode PCSetFromOptions_BJacobi(PC pc)
207: {
208:   PC_BJacobi     *jac = (PC_BJacobi*)pc->data;
210:   PetscInt       blocks;
211:   PetscTruth     flg;

214:   PetscOptionsHead("Block Jacobi options");
215:     PetscOptionsInt("-pc_bjacobi_blocks","Total number of blocks","PCBJacobiSetTotalBlocks",jac->n,&blocks,&flg);
216:     if (flg) {
217:       PCBJacobiSetTotalBlocks(pc,blocks,PETSC_NULL);
218:     }
219:     PetscOptionsName("-pc_bjacobi_truelocal","Use the true matrix, not preconditioner matrix to define matrix vector product in sub-problems","PCBJacobiSetUseTrueLocal",&flg);
220:     if (flg) {
221:       PCBJacobiSetUseTrueLocal(pc);
222:     }
223:   PetscOptionsTail();
224:   return(0);
225: }

229: static PetscErrorCode PCView_BJacobi(PC pc,PetscViewer viewer)
230: {
231:   PC_BJacobi     *jac = (PC_BJacobi*)pc->data;
233:   PetscMPIInt    rank;
234:   PetscInt       i;
235:   PetscTruth     iascii,isstring;
236:   PetscViewer    sviewer;

239:   PetscTypeCompare((PetscObject)viewer,PETSC_VIEWER_ASCII,&iascii);
240:   PetscTypeCompare((PetscObject)viewer,PETSC_VIEWER_STRING,&isstring);
241:   if (iascii) {
242:     if (jac->use_true_local) {
243:       PetscViewerASCIIPrintf(viewer,"  block Jacobi: using true local matrix, number of blocks = %D\n",jac->n);
244:     }
245:     PetscViewerASCIIPrintf(viewer,"  block Jacobi: number of blocks = %D\n",jac->n);
246:     MPI_Comm_rank(((PetscObject)pc)->comm,&rank);
247:     if (jac->same_local_solves) {
248:       PetscViewerASCIIPrintf(viewer,"  Local solve is same for all blocks, in the following KSP and PC objects:\n");
249:       PetscViewerGetSingleton(viewer,&sviewer);
250:       if (!rank && jac->ksp) {
251:         PetscViewerASCIIPushTab(viewer);
252:         KSPView(jac->ksp[0],sviewer);
253:         PetscViewerASCIIPopTab(viewer);
254:       }
255:       PetscViewerRestoreSingleton(viewer,&sviewer);
256:     } else {
257:       PetscInt n_global;
258:       MPI_Allreduce(&jac->n_local,&n_global,1,MPIU_INT,MPI_MAX,((PetscObject)pc)->comm);
259:       PetscViewerASCIIPrintf(viewer,"  Local solve info for each block is in the following KSP and PC objects:\n");
260:       PetscViewerASCIISynchronizedPrintf(viewer,"[%d] number of local blocks = %D, first local block number = %D\n",
261:                    rank,jac->n_local,jac->first_local);
262:       PetscViewerASCIIPushTab(viewer);
263:       for (i=0; i<n_global; i++) {
264:         PetscViewerGetSingleton(viewer,&sviewer);
265:         if (i < jac->n_local) {
266:           PetscViewerASCIISynchronizedPrintf(viewer,"[%d] local block number %D\n",rank,i);
267:           KSPView(jac->ksp[i],sviewer);
268:           PetscViewerASCIISynchronizedPrintf(viewer,"- - - - - - - - - - - - - - - - - -\n");
269:         }
270:         PetscViewerRestoreSingleton(viewer,&sviewer);
271:       }
272:       PetscViewerASCIIPopTab(viewer);
273:       PetscViewerFlush(viewer);
274:     }
275:   } else if (isstring) {
276:     PetscViewerStringSPrintf(viewer," blks=%D",jac->n);
277:     PetscViewerGetSingleton(viewer,&sviewer);
278:     if (jac->ksp) {KSPView(jac->ksp[0],sviewer);}
279:     PetscViewerRestoreSingleton(viewer,&sviewer);
280:   } else {
281:     SETERRQ1(PETSC_ERR_SUP,"Viewer type %s not supported for block Jacobi",((PetscObject)viewer)->type_name);
282:   }
283:   return(0);
284: }

286: /* -------------------------------------------------------------------------------------*/

291: PetscErrorCode  PCBJacobiSetUseTrueLocal_BJacobi(PC pc)
292: {
293:   PC_BJacobi   *jac;

296:   jac                 = (PC_BJacobi*)pc->data;
297:   jac->use_true_local = PETSC_TRUE;
298:   return(0);
299: }

305: PetscErrorCode  PCBJacobiGetSubKSP_BJacobi(PC pc,PetscInt *n_local,PetscInt *first_local,KSP **ksp)
306: {
307:   PC_BJacobi   *jac = (PC_BJacobi*)pc->data;;

310:   if (!pc->setupcalled) SETERRQ(PETSC_ERR_ARG_WRONGSTATE,"Must call KSPSetUp() or PCSetUp() first");

312:   if (n_local)     *n_local     = jac->n_local;
313:   if (first_local) *first_local = jac->first_local;
314:   *ksp                          = jac->ksp;
315:   jac->same_local_solves        = PETSC_FALSE; /* Assume that local solves are now different;
316:                                                   not necessarily true though!  This flag is 
317:                                                   used only for PCView_BJacobi() */
318:   return(0);
319: }

325: PetscErrorCode  PCBJacobiSetTotalBlocks_BJacobi(PC pc,PetscInt blocks,PetscInt *lens)
326: {
327:   PC_BJacobi     *jac = (PC_BJacobi*)pc->data;


332:   if (pc->setupcalled > 0 && jac->n!=blocks) SETERRQ(PETSC_ERR_ORDER,"Cannot alter number of blocks after PCSetUp()/KSPSetUp() has been called");
333:   jac->n = blocks;
334:   if (!lens) {
335:     jac->g_lens = 0;
336:   } else {
337:     PetscMalloc(blocks*sizeof(PetscInt),&jac->g_lens);
338:     PetscLogObjectMemory(pc,blocks*sizeof(PetscInt));
339:     PetscMemcpy(jac->g_lens,lens,blocks*sizeof(PetscInt));
340:   }
341:   return(0);
342: }

348: PetscErrorCode  PCBJacobiGetTotalBlocks_BJacobi(PC pc, PetscInt *blocks, const PetscInt *lens[])
349: {
350:   PC_BJacobi *jac = (PC_BJacobi*) pc->data;

353:   *blocks = jac->n;
354:   if (lens) *lens = jac->g_lens;
355:   return(0);
356: }

362: PetscErrorCode  PCBJacobiSetLocalBlocks_BJacobi(PC pc,PetscInt blocks,const PetscInt lens[])
363: {
364:   PC_BJacobi     *jac;

368:   jac = (PC_BJacobi*)pc->data;

370:   jac->n_local = blocks;
371:   if (!lens) {
372:     jac->l_lens = 0;
373:   } else {
374:     PetscMalloc(blocks*sizeof(PetscInt),&jac->l_lens);
375:     PetscLogObjectMemory(pc,blocks*sizeof(PetscInt));
376:     PetscMemcpy(jac->l_lens,lens,blocks*sizeof(PetscInt));
377:   }
378:   return(0);
379: }

385: PetscErrorCode  PCBJacobiGetLocalBlocks_BJacobi(PC pc, PetscInt *blocks, const PetscInt *lens[])
386: {
387:   PC_BJacobi *jac = (PC_BJacobi*) pc->data;

390:   *blocks = jac->n_local;
391:   if (lens) *lens = jac->l_lens;
392:   return(0);
393: }

396: /* -------------------------------------------------------------------------------------*/

400: /*@
401:    PCBJacobiSetUseTrueLocal - Sets a flag to indicate that the block 
402:    problem is associated with the linear system matrix instead of the
403:    default (where it is associated with the preconditioning matrix).
404:    That is, if the local system is solved iteratively then it iterates
405:    on the block from the matrix using the block from the preconditioner
406:    as the preconditioner for the local block.

408:    Collective on PC

410:    Input Parameters:
411: .  pc - the preconditioner context

413:    Options Database Key:
414: .  -pc_bjacobi_truelocal - Activates PCBJacobiSetUseTrueLocal()

416:    Notes:
417:    For the common case in which the preconditioning and linear 
418:    system matrices are identical, this routine is unnecessary.

420:    Level: intermediate

422: .keywords:  block, Jacobi, set, true, local, flag

424: .seealso: PCSetOperators(), PCBJacobiSetLocalBlocks()
425: @*/
426: PetscErrorCode  PCBJacobiSetUseTrueLocal(PC pc)
427: {
428:   PetscErrorCode ierr,(*f)(PC);

432:   PetscObjectQueryFunction((PetscObject)pc,"PCBJacobiSetUseTrueLocal_C",(void (**)(void))&f);
433:   if (f) {
434:     (*f)(pc);
435:   }

437:   return(0);
438: }

442: /*@C
443:    PCBJacobiGetSubKSP - Gets the local KSP contexts for all blocks on
444:    this processor.
445:    
446:    Note Collective

448:    Input Parameter:
449: .  pc - the preconditioner context

451:    Output Parameters:
452: +  n_local - the number of blocks on this processor, or PETSC_NULL
453: .  first_local - the global number of the first block on this processor, or PETSC_NULL
454: -  ksp - the array of KSP contexts

456:    Notes:  
457:    After PCBJacobiGetSubKSP() the array of KSP contexts is not to be freed.
458:    
459:    Currently for some matrix implementations only 1 block per processor 
460:    is supported.
461:    
462:    You must call KSPSetUp() or PCSetUp() before calling PCBJacobiGetSubKSP().

464:    Level: advanced

466: .keywords:  block, Jacobi, get, sub, KSP, context

468: .seealso: PCBJacobiGetSubKSP()
469: @*/
470: PetscErrorCode  PCBJacobiGetSubKSP(PC pc,PetscInt *n_local,PetscInt *first_local,KSP *ksp[])
471: {
472:   PetscErrorCode ierr,(*f)(PC,PetscInt *,PetscInt *,KSP **);

476:   PetscObjectQueryFunction((PetscObject)pc,"PCBJacobiGetSubKSP_C",(void (**)(void))&f);
477:   if (f) {
478:     (*f)(pc,n_local,first_local,ksp);
479:   } else {
480:     SETERRQ(PETSC_ERR_ARG_WRONG,"Cannot get subsolvers for this preconditioner");
481:   }
482:   return(0);
483: }

487: /*@
488:    PCBJacobiSetTotalBlocks - Sets the global number of blocks for the block
489:    Jacobi preconditioner.

491:    Collective on PC

493:    Input Parameters:
494: +  pc - the preconditioner context
495: .  blocks - the number of blocks
496: -  lens - [optional] integer array containing the size of each block

498:    Options Database Key:
499: .  -pc_bjacobi_blocks <blocks> - Sets the number of global blocks

501:    Notes:  
502:    Currently only a limited number of blocking configurations are supported.
503:    All processors sharing the PC must call this routine with the same data.

505:    Level: intermediate

507: .keywords:  set, number, Jacobi, global, total, blocks

509: .seealso: PCBJacobiSetUseTrueLocal(), PCBJacobiSetLocalBlocks()
510: @*/
511: PetscErrorCode  PCBJacobiSetTotalBlocks(PC pc,PetscInt blocks,const PetscInt lens[])
512: {
513:   PetscErrorCode ierr,(*f)(PC,PetscInt,const PetscInt[]);

517:   if (blocks <= 0) SETERRQ(PETSC_ERR_ARG_OUTOFRANGE,"Must have positive blocks");
518:   PetscObjectQueryFunction((PetscObject)pc,"PCBJacobiSetTotalBlocks_C",(void (**)(void))&f);
519:   if (f) {
520:     (*f)(pc,blocks,lens);
521:   }
522:   return(0);
523: }

527: /*@C
528:    PCBJacobiGetTotalBlocks - Gets the global number of blocks for the block
529:    Jacobi preconditioner.

531:    Collective on PC

533:    Input Parameter:
534: .  pc - the preconditioner context

536:    Output parameters:
537: +  blocks - the number of blocks
538: -  lens - integer array containing the size of each block

540:    Level: intermediate

542: .keywords:  get, number, Jacobi, global, total, blocks

544: .seealso: PCBJacobiSetUseTrueLocal(), PCBJacobiGetLocalBlocks()
545: @*/
546: PetscErrorCode  PCBJacobiGetTotalBlocks(PC pc, PetscInt *blocks, const PetscInt *lens[])
547: {
548:   PetscErrorCode ierr,(*f)(PC,PetscInt*, const PetscInt *[]);

553:   PetscObjectQueryFunction((PetscObject)pc,"PCBJacobiGetTotalBlocks_C",(void (**)(void))&f);
554:   if (f) {
555:     (*f)(pc,blocks,lens);
556:   }
557:   return(0);
558: }
559: 
562: /*@
563:    PCBJacobiSetLocalBlocks - Sets the local number of blocks for the block
564:    Jacobi preconditioner.

566:    Not Collective

568:    Input Parameters:
569: +  pc - the preconditioner context
570: .  blocks - the number of blocks
571: -  lens - [optional] integer array containing size of each block

573:    Note:  
574:    Currently only a limited number of blocking configurations are supported.

576:    Level: intermediate

578: .keywords: PC, set, number, Jacobi, local, blocks

580: .seealso: PCBJacobiSetUseTrueLocal(), PCBJacobiSetTotalBlocks()
581: @*/
582: PetscErrorCode  PCBJacobiSetLocalBlocks(PC pc,PetscInt blocks,const PetscInt lens[])
583: {
584:   PetscErrorCode ierr,(*f)(PC,PetscInt,const PetscInt []);

588:   if (blocks < 0) SETERRQ(PETSC_ERR_ARG_OUTOFRANGE,"Must have nonegative blocks");
589:   PetscObjectQueryFunction((PetscObject)pc,"PCBJacobiSetLocalBlocks_C",(void (**)(void))&f);
590:   if (f) {
591:     (*f)(pc,blocks,lens);
592:   }
593:   return(0);
594: }
595: 
598: /*@C
599:    PCBJacobiGetLocalBlocks - Gets the local number of blocks for the block
600:    Jacobi preconditioner.

602:    Not Collective

604:    Input Parameters:
605: +  pc - the preconditioner context
606: .  blocks - the number of blocks
607: -  lens - [optional] integer array containing size of each block

609:    Note:  
610:    Currently only a limited number of blocking configurations are supported.

612:    Level: intermediate

614: .keywords: PC, get, number, Jacobi, local, blocks

616: .seealso: PCBJacobiSetUseTrueLocal(), PCBJacobiGetTotalBlocks()
617: @*/
618: PetscErrorCode  PCBJacobiGetLocalBlocks(PC pc, PetscInt *blocks, const PetscInt *lens[])
619: {
620:   PetscErrorCode ierr,(*f)(PC,PetscInt*, const PetscInt *[]);

625:   PetscObjectQueryFunction((PetscObject)pc,"PCBJacobiGetLocalBlocks_C",(void (**)(void))&f);
626:   if (f) {
627:     (*f)(pc,blocks,lens);
628:   }
629:   return(0);
630: }

632: /* -----------------------------------------------------------------------------------*/

634: /*MC
635:    PCBJACOBI - Use block Jacobi preconditioning, each block is (approximately) solved with 
636:            its own KSP object.

638:    Options Database Keys:
639: .  -pc_bjacobi_truelocal - Activates PCBJacobiSetUseTrueLocal()

641:    Notes: Each processor can have one or more blocks, but a block cannot be shared by more
642:      than one processor. Defaults to one block per processor.

644:      To set options on the solvers for each block append -sub_ to all the KSP, KSP, and PC
645:         options database keys. For example, -sub_pc_type ilu -sub_pc_factor_levels 1 -sub_ksp_type preonly
646:         
647:      To set the options on the solvers separate for each block call PCBJacobiGetSubKSP()
648:          and set the options directly on the resulting KSP object (you can access its PC
649:          KSPGetPC())

651:    Level: beginner

653:    Concepts: block Jacobi

655: .seealso:  PCCreate(), PCSetType(), PCType (for list of available types), PC,
656:            PCASM, PCBJacobiSetUseTrueLocal(), PCBJacobiGetSubKSP(), PCBJacobiSetTotalBlocks(),
657:            PCBJacobiSetLocalBlocks(), PCSetModifySubmatrices()
658: M*/

663: PetscErrorCode  PCCreate_BJacobi(PC pc)
664: {
666:   PetscMPIInt    rank;
667:   PC_BJacobi     *jac;

670:   PetscNewLog(pc,PC_BJacobi,&jac);
671:   MPI_Comm_rank(((PetscObject)pc)->comm,&rank);
672:   pc->ops->apply              = 0;
673:   pc->ops->applytranspose     = 0;
674:   pc->ops->setup              = PCSetUp_BJacobi;
675:   pc->ops->destroy            = PCDestroy_BJacobi;
676:   pc->ops->setfromoptions     = PCSetFromOptions_BJacobi;
677:   pc->ops->view               = PCView_BJacobi;
678:   pc->ops->applyrichardson    = 0;

680:   pc->data               = (void*)jac;
681:   jac->n                 = -1;
682:   jac->n_local           = -1;
683:   jac->first_local       = rank;
684:   jac->ksp              = 0;
685:   jac->use_true_local    = PETSC_FALSE;
686:   jac->same_local_solves = PETSC_TRUE;
687:   jac->g_lens            = 0;
688:   jac->l_lens            = 0;
689:   jac->tp_mat            = 0;
690:   jac->tp_pmat           = 0;

692:   PetscObjectComposeFunctionDynamic((PetscObject)pc,"PCBJacobiSetUseTrueLocal_C",
693:                     "PCBJacobiSetUseTrueLocal_BJacobi",
694:                     PCBJacobiSetUseTrueLocal_BJacobi);
695:   PetscObjectComposeFunctionDynamic((PetscObject)pc,"PCBJacobiGetSubKSP_C","PCBJacobiGetSubKSP_BJacobi",
696:                     PCBJacobiGetSubKSP_BJacobi);
697:   PetscObjectComposeFunctionDynamic((PetscObject)pc,"PCBJacobiSetTotalBlocks_C","PCBJacobiSetTotalBlocks_BJacobi",
698:                     PCBJacobiSetTotalBlocks_BJacobi);
699:   PetscObjectComposeFunctionDynamic((PetscObject)pc,"PCBJacobiGetTotalBlocks_C","PCBJacobiGetTotalBlocks_BJacobi",
700:                     PCBJacobiGetTotalBlocks_BJacobi);
701:   PetscObjectComposeFunctionDynamic((PetscObject)pc,"PCBJacobiSetLocalBlocks_C","PCBJacobiSetLocalBlocks_BJacobi",
702:                     PCBJacobiSetLocalBlocks_BJacobi);
703:   PetscObjectComposeFunctionDynamic((PetscObject)pc,"PCBJacobiGetLocalBlocks_C","PCBJacobiGetLocalBlocks_BJacobi",
704:                     PCBJacobiGetLocalBlocks_BJacobi);

706:   return(0);
707: }

710: /* --------------------------------------------------------------------------------------------*/
711: /*
712:         These are for a single block per processor; works for AIJ, BAIJ; Seq and MPI
713: */
716: PetscErrorCode PCDestroy_BJacobi_Singleblock(PC pc)
717: {
718:   PC_BJacobi             *jac = (PC_BJacobi*)pc->data;
719:   PC_BJacobi_Singleblock *bjac = (PC_BJacobi_Singleblock*)jac->data;
720:   PetscErrorCode         ierr;

723:   /*
724:         If the on processor block had to be generated via a MatGetDiagonalBlock()
725:      that creates a copy, this frees the space
726:   */
727:   if (jac->tp_mat) {
728:     MatDestroy(jac->tp_mat);
729:   }
730:   if (jac->tp_pmat) {
731:     MatDestroy(jac->tp_pmat);
732:   }

734:   KSPDestroy(jac->ksp[0]);
735:   PetscFree(jac->ksp);
736:   VecDestroy(bjac->x);
737:   VecDestroy(bjac->y);
738:   PetscFree(jac->l_lens);
739:   PetscFree(jac->g_lens);
740:   PetscFree(bjac);
741:   PetscFree(jac);
742:   return(0);
743: }

747: PetscErrorCode PCSetUpOnBlocks_BJacobi_Singleblock(PC pc)
748: {
750:   PC_BJacobi     *jac = (PC_BJacobi*)pc->data;

753:   KSPSetUp(jac->ksp[0]);
754:   return(0);
755: }

759: PetscErrorCode PCApply_BJacobi_Singleblock(PC pc,Vec x,Vec y)
760: {
761:   PetscErrorCode         ierr;
762:   PC_BJacobi             *jac = (PC_BJacobi*)pc->data;
763:   PC_BJacobi_Singleblock *bjac = (PC_BJacobi_Singleblock*)jac->data;
764:   PetscScalar            *x_array,*y_array;

767:   /* 
768:       The VecPlaceArray() is to avoid having to copy the 
769:     y vector into the bjac->x vector. The reason for 
770:     the bjac->x vector is that we need a sequential vector
771:     for the sequential solve.
772:   */
773:   VecGetArray(x,&x_array);
774:   VecGetArray(y,&y_array);
775:   VecPlaceArray(bjac->x,x_array);
776:   VecPlaceArray(bjac->y,y_array);
777:   KSPSolve(jac->ksp[0],bjac->x,bjac->y);
778:   VecResetArray(bjac->x);
779:   VecResetArray(bjac->y);
780:   VecRestoreArray(x,&x_array);
781:   VecRestoreArray(y,&y_array);
782:   return(0);
783: }

787: PetscErrorCode PCApplySymmetricLeft_BJacobi_Singleblock(PC pc,Vec x,Vec y)
788: {
789:   PetscErrorCode         ierr;
790:   PC_BJacobi             *jac = (PC_BJacobi*)pc->data;
791:   PC_BJacobi_Singleblock *bjac = (PC_BJacobi_Singleblock*)jac->data;
792:   PetscScalar            *x_array,*y_array;
793:   PC                     subpc;

796:   /* 
797:       The VecPlaceArray() is to avoid having to copy the 
798:     y vector into the bjac->x vector. The reason for 
799:     the bjac->x vector is that we need a sequential vector
800:     for the sequential solve.
801:   */
802:   VecGetArray(x,&x_array);
803:   VecGetArray(y,&y_array);
804:   VecPlaceArray(bjac->x,x_array);
805:   VecPlaceArray(bjac->y,y_array);

807:   /* apply the symmetric left portion of the inner PC operator */
808:   /* note this by-passes the inner KSP and its options completely */

810:   KSPGetPC(jac->ksp[0],&subpc);
811:   PCApplySymmetricLeft(subpc,bjac->x,bjac->y);
812:   VecResetArray(bjac->x);
813:   VecResetArray(bjac->y);

815:   VecRestoreArray(x,&x_array);
816:   VecRestoreArray(y,&y_array);
817:   return(0);
818: }

822: PetscErrorCode PCApplySymmetricRight_BJacobi_Singleblock(PC pc,Vec x,Vec y)
823: {
824:   PetscErrorCode         ierr;
825:   PC_BJacobi             *jac = (PC_BJacobi*)pc->data;
826:   PC_BJacobi_Singleblock *bjac = (PC_BJacobi_Singleblock*)jac->data;
827:   PetscScalar            *x_array,*y_array;
828:   PC                     subpc;

831:   /* 
832:       The VecPlaceArray() is to avoid having to copy the 
833:     y vector into the bjac->x vector. The reason for 
834:     the bjac->x vector is that we need a sequential vector
835:     for the sequential solve.
836:   */
837:   VecGetArray(x,&x_array);
838:   VecGetArray(y,&y_array);
839:   VecPlaceArray(bjac->x,x_array);
840:   VecPlaceArray(bjac->y,y_array);

842:   /* apply the symmetric right portion of the inner PC operator */
843:   /* note this by-passes the inner KSP and its options completely */

845:   KSPGetPC(jac->ksp[0],&subpc);
846:   PCApplySymmetricRight(subpc,bjac->x,bjac->y);

848:   VecRestoreArray(x,&x_array);
849:   VecRestoreArray(y,&y_array);
850:   return(0);
851: }

855: PetscErrorCode PCApplyTranspose_BJacobi_Singleblock(PC pc,Vec x,Vec y)
856: {
857:   PetscErrorCode         ierr;
858:   PC_BJacobi             *jac = (PC_BJacobi*)pc->data;
859:   PC_BJacobi_Singleblock *bjac = (PC_BJacobi_Singleblock*)jac->data;
860:   PetscScalar            *x_array,*y_array;

863:   /* 
864:       The VecPlaceArray() is to avoid having to copy the 
865:     y vector into the bjac->x vector. The reason for 
866:     the bjac->x vector is that we need a sequential vector
867:     for the sequential solve.
868:   */
869:   VecGetArray(x,&x_array);
870:   VecGetArray(y,&y_array);
871:   VecPlaceArray(bjac->x,x_array);
872:   VecPlaceArray(bjac->y,y_array);
873:   KSPSolveTranspose(jac->ksp[0],bjac->x,bjac->y);
874:   VecResetArray(bjac->x);
875:   VecResetArray(bjac->y);
876:   VecRestoreArray(x,&x_array);
877:   VecRestoreArray(y,&y_array);
878:   return(0);
879: }

883: static PetscErrorCode PCSetUp_BJacobi_Singleblock(PC pc,Mat mat,Mat pmat)
884: {
885:   PC_BJacobi             *jac = (PC_BJacobi*)pc->data;
886:   PetscErrorCode         ierr;
887:   PetscInt               m;
888:   KSP                    ksp;
889:   Vec                    x,y;
890:   PC_BJacobi_Singleblock *bjac;
891:   PetscTruth             wasSetup;


895:   /* set default direct solver with no Krylov method */
896:   if (!pc->setupcalled) {
897:     const char *prefix;
898:     wasSetup = PETSC_FALSE;
899:     KSPCreate(PETSC_COMM_SELF,&ksp);
900:     PetscObjectIncrementTabLevel((PetscObject)ksp,(PetscObject)pc,1);
901:     PetscLogObjectParent(pc,ksp);
902:     KSPSetType(ksp,KSPPREONLY);
903:     PCGetOptionsPrefix(pc,&prefix);
904:     KSPSetOptionsPrefix(ksp,prefix);
905:     KSPAppendOptionsPrefix(ksp,"sub_");
906:     /*
907:       The reason we need to generate these vectors is to serve 
908:       as the right-hand side and solution vector for the solve on the 
909:       block. We do not need to allocate space for the vectors since
910:       that is provided via VecPlaceArray() just before the call to 
911:       KSPSolve() on the block.
912:     */
913:     MatGetSize(pmat,&m,&m);
914:     VecCreateSeqWithArray(PETSC_COMM_SELF,m,PETSC_NULL,&x);
915:     VecCreateSeqWithArray(PETSC_COMM_SELF,m,PETSC_NULL,&y);
916:     PetscLogObjectParent(pc,x);
917:     PetscLogObjectParent(pc,y);

919:     pc->ops->destroy             = PCDestroy_BJacobi_Singleblock;
920:     pc->ops->apply               = PCApply_BJacobi_Singleblock;
921:     pc->ops->applysymmetricleft  = PCApplySymmetricLeft_BJacobi_Singleblock;
922:     pc->ops->applysymmetricright = PCApplySymmetricRight_BJacobi_Singleblock;
923:     pc->ops->applytranspose      = PCApplyTranspose_BJacobi_Singleblock;
924:     pc->ops->setuponblocks       = PCSetUpOnBlocks_BJacobi_Singleblock;

926:     PetscNewLog(pc,PC_BJacobi_Singleblock,&bjac);
927:     bjac->x      = x;
928:     bjac->y      = y;

930:     PetscMalloc(sizeof(KSP),&jac->ksp);
931:     jac->ksp[0] = ksp;
932:     jac->data    = (void*)bjac;
933:   } else {
934:     wasSetup = PETSC_TRUE;
935:     ksp = jac->ksp[0];
936:     bjac = (PC_BJacobi_Singleblock *)jac->data;
937:   }
938:   if (jac->use_true_local) {
939:     KSPSetOperators(ksp,mat,pmat,pc->flag);
940:   }  else {
941:     KSPSetOperators(ksp,pmat,pmat,pc->flag);
942:   }
943:   if (!wasSetup && pc->setfromoptionscalled) {
944:     KSPSetFromOptions(ksp);
945:   }
946:   return(0);
947: }

949: /* ---------------------------------------------------------------------------------------------*/

953: PetscErrorCode PCDestroy_BJacobi_Multiblock(PC pc)
954: {
955:   PC_BJacobi            *jac = (PC_BJacobi*)pc->data;
956:   PC_BJacobi_Multiblock *bjac = (PC_BJacobi_Multiblock*)jac->data;
957:   PetscErrorCode        ierr;
958:   PetscInt              i;

961:   MatDestroyMatrices(jac->n_local,&bjac->pmat);
962:   if (jac->use_true_local) {
963:     MatDestroyMatrices(jac->n_local,&bjac->mat);
964:   }

966:   /*
967:         If the on processor block had to be generated via a MatGetDiagonalBlock()
968:      that creates a copy, this frees the space
969:   */
970:   if (jac->tp_mat) {
971:     MatDestroy(jac->tp_mat);
972:   }
973:   if (jac->tp_pmat) {
974:     MatDestroy(jac->tp_pmat);
975:   }

977:   for (i=0; i<jac->n_local; i++) {
978:     KSPDestroy(jac->ksp[i]);
979:     VecDestroy(bjac->x[i]);
980:     VecDestroy(bjac->y[i]);
981:     ISDestroy(bjac->is[i]);
982:   }
983:   PetscFree(jac->ksp);
984:   PetscFree2(bjac->x,bjac->y);
985:   PetscFree(bjac->starts);
986:   PetscFree(bjac->is);
987:   PetscFree(bjac);
988:   PetscFree(jac->l_lens);
989:   PetscFree(jac->g_lens);
990:   PetscFree(jac);
991:   return(0);
992: }

996: PetscErrorCode PCSetUpOnBlocks_BJacobi_Multiblock(PC pc)
997: {
998:   PC_BJacobi     *jac = (PC_BJacobi*)pc->data;
1000:   PetscInt       i,n_local = jac->n_local;

1003:   for (i=0; i<n_local; i++) {
1004:     KSPSetUp(jac->ksp[i]);
1005:   }
1006:   return(0);
1007: }

1009: /*
1010:       Preconditioner for block Jacobi 
1011: */
1014: PetscErrorCode PCApply_BJacobi_Multiblock(PC pc,Vec x,Vec y)
1015: {
1016:   PC_BJacobi            *jac = (PC_BJacobi*)pc->data;
1017:   PetscErrorCode        ierr;
1018:   PetscInt              i,n_local = jac->n_local;
1019:   PC_BJacobi_Multiblock *bjac = (PC_BJacobi_Multiblock*)jac->data;
1020:   PetscScalar           *xin,*yin;

1023:   VecGetArray(x,&xin);
1024:   VecGetArray(y,&yin);
1025:   for (i=0; i<n_local; i++) {
1026:     /* 
1027:        To avoid copying the subvector from x into a workspace we instead 
1028:        make the workspace vector array point to the subpart of the array of
1029:        the global vector.
1030:     */
1031:     VecPlaceArray(bjac->x[i],xin+bjac->starts[i]);
1032:     VecPlaceArray(bjac->y[i],yin+bjac->starts[i]);

1034:     PetscLogEventBegin(PC_SetUpOnBlocks,jac->ksp[i],bjac->x[i],bjac->y[i],0);
1035:     KSPSolve(jac->ksp[i],bjac->x[i],bjac->y[i]);
1036:     PetscLogEventEnd(PC_SetUpOnBlocks,jac->ksp[i],bjac->x[i],bjac->y[i],0);

1038:     VecResetArray(bjac->x[i]);
1039:     VecResetArray(bjac->y[i]);
1040:   }
1041:   VecRestoreArray(x,&xin);
1042:   VecRestoreArray(y,&yin);
1043:   return(0);
1044: }

1046: /*
1047:       Preconditioner for block Jacobi 
1048: */
1051: PetscErrorCode PCApplyTranspose_BJacobi_Multiblock(PC pc,Vec x,Vec y)
1052: {
1053:   PC_BJacobi            *jac = (PC_BJacobi*)pc->data;
1054:   PetscErrorCode        ierr;
1055:   PetscInt              i,n_local = jac->n_local;
1056:   PC_BJacobi_Multiblock *bjac = (PC_BJacobi_Multiblock*)jac->data;
1057:   PetscScalar           *xin,*yin;

1060:   VecGetArray(x,&xin);
1061:   VecGetArray(y,&yin);
1062:   for (i=0; i<n_local; i++) {
1063:     /* 
1064:        To avoid copying the subvector from x into a workspace we instead 
1065:        make the workspace vector array point to the subpart of the array of
1066:        the global vector.
1067:     */
1068:     VecPlaceArray(bjac->x[i],xin+bjac->starts[i]);
1069:     VecPlaceArray(bjac->y[i],yin+bjac->starts[i]);

1071:     PetscLogEventBegin(PC_ApplyTransposeOnBlocks,jac->ksp[i],bjac->x[i],bjac->y[i],0);
1072:     KSPSolveTranspose(jac->ksp[i],bjac->x[i],bjac->y[i]);
1073:     PetscLogEventEnd(PC_ApplyTransposeOnBlocks,jac->ksp[i],bjac->x[i],bjac->y[i],0);
1074:   }
1075:   VecRestoreArray(x,&xin);
1076:   VecRestoreArray(y,&yin);
1077:   return(0);
1078: }

1082: static PetscErrorCode PCSetUp_BJacobi_Multiblock(PC pc,Mat mat,Mat pmat)
1083: {
1084:   PC_BJacobi             *jac = (PC_BJacobi*)pc->data;
1085:   PetscErrorCode         ierr;
1086:   PetscInt               m,n_local,N,M,start,i;
1087:   const char             *prefix,*pprefix,*mprefix;
1088:   KSP                    ksp;
1089:   Vec                    x,y;
1090:   PC_BJacobi_Multiblock  *bjac = (PC_BJacobi_Multiblock*)jac->data;
1091:   PC                     subpc;
1092:   IS                     is;
1093:   MatReuse               scall = MAT_REUSE_MATRIX;

1096:   MatGetLocalSize(pc->pmat,&M,&N);

1098:   n_local = jac->n_local;

1100:   if (jac->use_true_local) {
1101:     PetscTruth same;
1102:     PetscTypeCompare((PetscObject)mat,((PetscObject)pmat)->type_name,&same);
1103:     if (!same) SETERRQ(PETSC_ERR_ARG_INCOMP,"Matrices not of same type");
1104:   }

1106:   if (!pc->setupcalled) {
1107:     scall                  = MAT_INITIAL_MATRIX;
1108:     pc->ops->destroy       = PCDestroy_BJacobi_Multiblock;
1109:     pc->ops->apply         = PCApply_BJacobi_Multiblock;
1110:     pc->ops->applytranspose= PCApplyTranspose_BJacobi_Multiblock;
1111:     pc->ops->setuponblocks = PCSetUpOnBlocks_BJacobi_Multiblock;

1113:     PetscNewLog(pc,PC_BJacobi_Multiblock,&bjac);
1114:     PetscMalloc(n_local*sizeof(KSP),&jac->ksp);
1115:     PetscLogObjectMemory(pc,sizeof(n_local*sizeof(KSP)));
1116:     PetscMalloc2(n_local,Vec,&bjac->x,n_local,Vec,&bjac->y);
1117:     PetscMalloc(n_local*sizeof(PetscScalar),&bjac->starts);
1118:     PetscLogObjectMemory(pc,sizeof(n_local*sizeof(PetscScalar)));
1119: 
1120:     jac->data    = (void*)bjac;
1121:     PetscMalloc(n_local*sizeof(IS),&bjac->is);
1122:     PetscLogObjectMemory(pc,sizeof(n_local*sizeof(IS)));

1124:     start = 0;
1125:     for (i=0; i<n_local; i++) {
1126:       KSPCreate(PETSC_COMM_SELF,&ksp);
1127:       PetscObjectIncrementTabLevel((PetscObject)ksp,(PetscObject)pc,1);
1128:       PetscLogObjectParent(pc,ksp);
1129:       KSPSetType(ksp,KSPPREONLY);
1130:       KSPGetPC(ksp,&subpc);
1131:       PCGetOptionsPrefix(pc,&prefix);
1132:       KSPSetOptionsPrefix(ksp,prefix);
1133:       KSPAppendOptionsPrefix(ksp,"sub_");

1135:       m = jac->l_lens[i];

1137:       /*
1138:       The reason we need to generate these vectors is to serve 
1139:       as the right-hand side and solution vector for the solve on the 
1140:       block. We do not need to allocate space for the vectors since
1141:       that is provided via VecPlaceArray() just before the call to 
1142:       KSPSolve() on the block.

1144:       */
1145:       VecCreateSeq(PETSC_COMM_SELF,m,&x);
1146:       VecCreateSeqWithArray(PETSC_COMM_SELF,m,PETSC_NULL,&y);
1147:       PetscLogObjectParent(pc,x);
1148:       PetscLogObjectParent(pc,y);
1149:       bjac->x[i]      = x;
1150:       bjac->y[i]      = y;
1151:       bjac->starts[i] = start;
1152:       jac->ksp[i]    = ksp;

1154:       ISCreateStride(PETSC_COMM_SELF,m,start,1,&is);
1155:       bjac->is[i] = is;
1156:       PetscLogObjectParent(pc,is);

1158:       start += m;
1159:     }
1160:   } else {
1161:     bjac = (PC_BJacobi_Multiblock*)jac->data;
1162:     /* 
1163:        Destroy the blocks from the previous iteration
1164:     */
1165:     if (pc->flag == DIFFERENT_NONZERO_PATTERN) {
1166:       MatDestroyMatrices(n_local,&bjac->pmat);
1167:       if (jac->use_true_local) {
1168:         MatDestroyMatrices(n_local,&bjac->mat);
1169:       }
1170:       scall = MAT_INITIAL_MATRIX;
1171:     }
1172:   }

1174:   MatGetSubMatrices(pmat,n_local,bjac->is,bjac->is,scall,&bjac->pmat);
1175:   if (jac->use_true_local) {
1176:     PetscObjectGetOptionsPrefix((PetscObject)mat,&mprefix);
1177:     MatGetSubMatrices(mat,n_local,bjac->is,bjac->is,scall,&bjac->mat);
1178:   }
1179:   /* Return control to the user so that the submatrices can be modified (e.g., to apply
1180:      different boundary conditions for the submatrices than for the global problem) */
1181:   PCModifySubMatrices(pc,n_local,bjac->is,bjac->is,bjac->pmat,pc->modifysubmatricesP);

1183:   PetscObjectGetOptionsPrefix((PetscObject)pmat,&pprefix);
1184:   for (i=0; i<n_local; i++) {
1185:     PetscLogObjectParent(pc,bjac->pmat[i]);
1186:     PetscObjectSetOptionsPrefix((PetscObject)bjac->pmat[i],pprefix);
1187:     if (jac->use_true_local) {
1188:       PetscLogObjectParent(pc,bjac->mat[i]);
1189:       PetscObjectSetOptionsPrefix((PetscObject)bjac->mat[i],mprefix);
1190:       KSPSetOperators(jac->ksp[i],bjac->mat[i],bjac->pmat[i],pc->flag);
1191:     } else {
1192:       KSPSetOperators(jac->ksp[i],bjac->pmat[i],bjac->pmat[i],pc->flag);
1193:     }
1194:     if(pc->setfromoptionscalled){
1195:       KSPSetFromOptions(jac->ksp[i]);
1196:     }
1197:   }
1198:   return(0);
1199: }