Actual source code: shell.c

petsc-master 2017-01-19
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  2: /*
  3:    This provides a simple shell for Fortran (and C programmers) to
  4:   create a very simple matrix class for use with KSP without coding
  5:   much of anything.
  6: */

  8:  #include <petsc/private/matimpl.h>

 10: struct _MatShellOps {
 11:   /*   0 */
 12:   PetscErrorCode (*mult)(Mat,Vec,Vec);
 13:   /*   5 */
 14:   PetscErrorCode (*multtranspose)(Mat,Vec,Vec);
 15:   /*  10 */
 16:   /*  15 */
 17:   PetscErrorCode (*getdiagonal)(Mat,Vec);
 18:   /*  20 */
 19:   /*  24 */
 20:   /*  29 */
 21:   /*  34 */
 22:   /*  39 */
 23:   PetscErrorCode (*copy)(Mat,Mat,MatStructure);
 24:   /*  44 */
 25:   PetscErrorCode (*diagonalset)(Mat,Vec,InsertMode);
 26:   /*  49 */
 27:   /*  54 */
 28:   /*  59 */
 29:   PetscErrorCode (*destroy)(Mat);
 30:   /*  64 */
 31:   /*  69 */
 32:   /*  74 */
 33:   /*  79 */
 34:   /*  84 */
 35:   /*  89 */
 36:   /*  94 */
 37:   /*  99 */
 38:   /* 104 */
 39:   /* 109 */
 40:   /* 114 */
 41:   /* 119 */
 42:   /* 124 */
 43:   /* 129 */
 44:   /* 134 */
 45:   /* 139 */
 46:   /* 144 */
 47: };

 49: typedef struct {
 50:   struct _MatShellOps ops[1];

 52:   PetscScalar vscale,vshift;
 53:   Vec         dshift;
 54:   Vec         left,right;
 55:   Vec         dshift_owned,left_owned,right_owned;
 56:   Vec         left_work,right_work;
 57:   Vec         left_add_work,right_add_work;
 58:   PetscBool   usingscaled;
 59:   void        *ctx;
 60: } Mat_Shell;
 61: /*
 62:  The most general expression for the matrix is

 64:  S = L (a A + B) R

 66:  where
 67:  A is the matrix defined by the user's function
 68:  a is a scalar multiple
 69:  L is left scaling
 70:  R is right scaling
 71:  B is a diagonal shift defined by
 72:    diag(dshift) if the vector dshift is non-NULL
 73:    vscale*identity otherwise

 75:  The following identities apply:

 77:  Scale by c:
 78:   c [L (a A + B) R] = L [(a c) A + c B] R

 80:  Shift by c:
 81:   [L (a A + B) R] + c = L [a A + (B + c Linv Rinv)] R

 83:  Diagonal scaling is achieved by simply multiplying with existing L and R vectors

 85:  In the data structure:

 87:  vscale=1.0  means no special scaling will be applied
 88:  dshift=NULL means a constant diagonal shift (fall back to vshift)
 89:  vshift=0.0  means no constant diagonal shift, note that vshift is only used if dshift is NULL
 90: */

 92: static PetscErrorCode MatMult_Shell(Mat,Vec,Vec);
 93: static PetscErrorCode MatMultTranspose_Shell(Mat,Vec,Vec);
 94: static PetscErrorCode MatGetDiagonal_Shell(Mat,Vec);
 95: static PetscErrorCode MatCopy_Shell(Mat,Mat,MatStructure);

 97: static PetscErrorCode MatShellUseScaledMethods(Mat Y)
 98: {
 99:   Mat_Shell *shell = (Mat_Shell*)Y->data;

102:   if (shell->usingscaled) return(0);
103:   shell->ops->mult  = Y->ops->mult;
104:   Y->ops->mult = MatMult_Shell;
105:   if (Y->ops->multtranspose) {
106:     shell->ops->multtranspose  = Y->ops->multtranspose;
107:     Y->ops->multtranspose = MatMultTranspose_Shell;
108:   }
109:   if (Y->ops->getdiagonal) {
110:     shell->ops->getdiagonal  = Y->ops->getdiagonal;
111:     Y->ops->getdiagonal = MatGetDiagonal_Shell;
112:   }
113:   if (Y->ops->copy) {
114:     shell->ops->copy  = Y->ops->copy;
115:     Y->ops->copy = MatCopy_Shell;
116:   }
117:   shell->usingscaled = PETSC_TRUE;
118:   return(0);
119: }

121: static PetscErrorCode MatShellPreScaleLeft(Mat A,Vec x,Vec *xx)
122: {
123:   Mat_Shell      *shell = (Mat_Shell*)A->data;

127:   *xx = NULL;
128:   if (!shell->left) {
129:     *xx = x;
130:   } else {
131:     if (!shell->left_work) {VecDuplicate(shell->left,&shell->left_work);}
132:     VecPointwiseMult(shell->left_work,x,shell->left);
133:     *xx  = shell->left_work;
134:   }
135:   return(0);
136: }

138: static PetscErrorCode MatShellPreScaleRight(Mat A,Vec x,Vec *xx)
139: {
140:   Mat_Shell      *shell = (Mat_Shell*)A->data;

144:   *xx = NULL;
145:   if (!shell->right) {
146:     *xx = x;
147:   } else {
148:     if (!shell->right_work) {VecDuplicate(shell->right,&shell->right_work);}
149:     VecPointwiseMult(shell->right_work,x,shell->right);
150:     *xx  = shell->right_work;
151:   }
152:   return(0);
153: }

155: static PetscErrorCode MatShellPostScaleLeft(Mat A,Vec x)
156: {
157:   Mat_Shell      *shell = (Mat_Shell*)A->data;

161:   if (shell->left) {VecPointwiseMult(x,x,shell->left);}
162:   return(0);
163: }

165: static PetscErrorCode MatShellPostScaleRight(Mat A,Vec x)
166: {
167:   Mat_Shell      *shell = (Mat_Shell*)A->data;

171:   if (shell->right) {VecPointwiseMult(x,x,shell->right);}
172:   return(0);
173: }

175: static PetscErrorCode MatShellShiftAndScale(Mat A,Vec X,Vec Y)
176: {
177:   Mat_Shell      *shell = (Mat_Shell*)A->data;

181:   if (shell->dshift) {          /* get arrays because there is no VecPointwiseMultAdd() */
182:     PetscInt          i,m;
183:     const PetscScalar *x,*d;
184:     PetscScalar       *y;
185:     VecGetLocalSize(X,&m);
186:     VecGetArrayRead(shell->dshift,&d);
187:     VecGetArrayRead(X,&x);
188:     VecGetArray(Y,&y);
189:     for (i=0; i<m; i++) y[i] = shell->vscale*y[i] + d[i]*x[i];
190:     VecRestoreArrayRead(shell->dshift,&d);
191:     VecRestoreArrayRead(X,&x);
192:     VecRestoreArray(Y,&y);
193:   } else if (PetscAbsScalar(shell->vshift) != 0) {
194:     VecAXPBY(Y,shell->vshift,shell->vscale,X);
195:   } else if (shell->vscale != 1.0) {
196:     VecScale(Y,shell->vscale);
197:   }
198:   return(0);
199: }

201: /*@
202:     MatShellGetContext - Returns the user-provided context associated with a shell matrix.

204:     Not Collective

206:     Input Parameter:
207: .   mat - the matrix, should have been created with MatCreateShell()

209:     Output Parameter:
210: .   ctx - the user provided context

212:     Level: advanced

214:    Fortran Notes: To use this from Fortran you must write a Fortran interface definition for this
215:     function that tells Fortran the Fortran derived data type that you are passing in as the ctx argument.

217: .keywords: matrix, shell, get, context

219: .seealso: MatCreateShell(), MatShellSetOperation(), MatShellSetContext()
220: @*/
221: PetscErrorCode  MatShellGetContext(Mat mat,void *ctx)
222: {
224:   PetscBool      flg;

229:   PetscObjectTypeCompare((PetscObject)mat,MATSHELL,&flg);
230:   if (flg) *(void**)ctx = ((Mat_Shell*)(mat->data))->ctx;
231:   else SETERRQ(PetscObjectComm((PetscObject)mat),PETSC_ERR_SUP,"Cannot get context from non-shell matrix");
232:   return(0);
233: }

235: PetscErrorCode MatDestroy_Shell(Mat mat)
236: {
238:   Mat_Shell      *shell = (Mat_Shell*)mat->data;

241:   if (shell->ops->destroy) {
242:     (*shell->ops->destroy)(mat);
243:   }
244:   VecDestroy(&shell->left_owned);
245:   VecDestroy(&shell->right_owned);
246:   VecDestroy(&shell->dshift_owned);
247:   VecDestroy(&shell->left_work);
248:   VecDestroy(&shell->right_work);
249:   VecDestroy(&shell->left_add_work);
250:   VecDestroy(&shell->right_add_work);
251:   PetscFree(mat->data);
252:   return(0);
253: }

255: PetscErrorCode MatCopy_Shell(Mat A,Mat B,MatStructure str)
256: {
257:   Mat_Shell       *shellA = (Mat_Shell*)A->data,*shellB = (Mat_Shell*)B->data;
258:   PetscBool       matflg,shellflg;
259:   PetscErrorCode  ierr;

262:   PetscObjectTypeCompare((PetscObject)B,MATSHELL,&matflg);
263:   if(!matflg) { SETERRQ(PetscObjectComm((PetscObject)A),PETSC_ERR_ARG_NOTSAMETYPE,"Output matrix must be a MATSHELL"); }

265:   MatShellUseScaledMethods(B);
266:   PetscMemcmp(A->ops,B->ops,sizeof(struct _MatOps),&matflg);
267:   PetscMemcmp(shellA->ops,shellB->ops,sizeof(struct _MatShellOps),&shellflg);
268:   if (!matflg || !shellflg) { SETERRQ(PetscObjectComm((PetscObject)A),PETSC_ERR_ARG_INCOMP,"Matrices cannot be copied because they have different operations"); }

270:   (*shellA->ops->copy)(A,B,str);
271:   shellB->vscale = shellA->vscale;
272:   shellB->vshift = shellA->vshift;
273:   if (shellA->dshift_owned) {
274:     if (!shellB->dshift_owned) {
275:       VecDuplicate(shellA->dshift_owned,&shellB->dshift_owned);
276:     }
277:     VecCopy(shellA->dshift_owned,shellB->dshift_owned);
278:     shellB->dshift = shellB->dshift_owned;
279:   } else {
280:     shellB->dshift = NULL;
281:   }
282:   if (shellA->left_owned) {
283:     if (!shellB->left_owned) {
284:       VecDuplicate(shellA->left_owned,&shellB->left_owned);
285:     }
286:     VecCopy(shellA->left_owned,shellB->left_owned);
287:     shellB->left = shellB->left_owned;
288:   } else {
289:     shellB->left = NULL;
290:   }
291:   if (shellA->right_owned) {
292:     if (!shellB->right_owned) {
293:       VecDuplicate(shellA->right_owned,&shellB->right_owned);
294:     }
295:     VecCopy(shellA->right_owned,shellB->right_owned);
296:     shellB->right = shellB->right_owned;
297:   } else {
298:     shellB->right = NULL;
299:   }
300:   return(0);
301: }

303: PetscErrorCode MatMult_Shell(Mat A,Vec x,Vec y)
304: {
305:   Mat_Shell        *shell = (Mat_Shell*)A->data;
306:   PetscErrorCode   ierr;
307:   Vec              xx;
308:   PetscObjectState instate,outstate;

311:   MatShellPreScaleRight(A,x,&xx);
312:   PetscObjectStateGet((PetscObject)y, &instate);
313:   (*shell->ops->mult)(A,xx,y);
314:   PetscObjectStateGet((PetscObject)y, &outstate);
315:   if (instate == outstate) {
316:     /* increase the state of the output vector since the user did not update its state themself as should have been done */
317:     PetscObjectStateIncrease((PetscObject)y);
318:   }
319:   MatShellShiftAndScale(A,xx,y);
320:   MatShellPostScaleLeft(A,y);
321:   return(0);
322: }

324: PetscErrorCode MatMultAdd_Shell(Mat A,Vec x,Vec y,Vec z)
325: {
326:   Mat_Shell      *shell = (Mat_Shell*)A->data;

330:   if (y == z) {
331:     if (!shell->right_add_work) {VecDuplicate(z,&shell->right_add_work);}
332:     MatMult(A,x,shell->right_add_work);
333:     VecAXPY(z,1.0,shell->right_add_work);
334:   } else {
335:     MatMult(A,x,z);
336:     VecAXPY(z,1.0,y);
337:   }
338:   return(0);
339: }

341: PetscErrorCode MatMultTranspose_Shell(Mat A,Vec x,Vec y)
342: {
343:   Mat_Shell        *shell = (Mat_Shell*)A->data;
344:   PetscErrorCode   ierr;
345:   Vec              xx;
346:   PetscObjectState instate,outstate;

349:   MatShellPreScaleLeft(A,x,&xx);
350:   PetscObjectStateGet((PetscObject)y, &instate);
351:   (*shell->ops->multtranspose)(A,xx,y);
352:   PetscObjectStateGet((PetscObject)y, &outstate);
353:   if (instate == outstate) {
354:     /* increase the state of the output vector since the user did not update its state themself as should have been done */
355:     PetscObjectStateIncrease((PetscObject)y);
356:   }
357:   MatShellShiftAndScale(A,xx,y);
358:   MatShellPostScaleRight(A,y);
359:   return(0);
360: }

362: PetscErrorCode MatMultTransposeAdd_Shell(Mat A,Vec x,Vec y,Vec z)
363: {
364:   Mat_Shell      *shell = (Mat_Shell*)A->data;

368:   if (y == z) {
369:     if (!shell->left_add_work) {VecDuplicate(z,&shell->left_add_work);}
370:     MatMultTranspose(A,x,shell->left_add_work);
371:     VecWAXPY(z,1.0,shell->left_add_work,y);
372:   } else {
373:     MatMultTranspose(A,x,z);
374:     VecAXPY(z,1.0,y);
375:   }
376:   return(0);
377: }

379: PetscErrorCode MatGetDiagonal_Shell(Mat A,Vec v)
380: {
381:   Mat_Shell      *shell = (Mat_Shell*)A->data;

385:   (*shell->ops->getdiagonal)(A,v);
386:   VecScale(v,shell->vscale);
387:   if (shell->dshift) {
388:     VecPointwiseMult(v,v,shell->dshift);
389:   } else {
390:     VecShift(v,shell->vshift);
391:   }
392:   if (shell->left)  {VecPointwiseMult(v,v,shell->left);}
393:   if (shell->right) {VecPointwiseMult(v,v,shell->right);}
394:   return(0);
395: }

397: PetscErrorCode MatShift_Shell(Mat Y,PetscScalar a)
398: {
399:   Mat_Shell      *shell = (Mat_Shell*)Y->data;

403:   if (shell->left || shell->right || shell->dshift) {
404:     if (!shell->dshift) {
405:       if (!shell->dshift_owned) {VecDuplicate(shell->left ? shell->left : shell->right, &shell->dshift_owned);}
406:       shell->dshift = shell->dshift_owned;
407:       VecSet(shell->dshift,shell->vshift+a);
408:     } else {VecScale(shell->dshift,a);}
409:     if (shell->left)  {VecPointwiseDivide(shell->dshift,shell->dshift,shell->left);}
410:     if (shell->right) {VecPointwiseDivide(shell->dshift,shell->dshift,shell->right);}
411:   } else shell->vshift += a;
412:   MatShellUseScaledMethods(Y);
413:   return(0);
414: }

416: PetscErrorCode MatDiagonalSet_Shell(Mat A,Vec D,InsertMode ins)
417: {
418:   Mat_Shell      *shell = (Mat_Shell*)A->data;

422:   if (shell->vscale != 1.0 || shell->left || shell->right) {
423:     SETERRQ(PetscObjectComm((PetscObject)A),PETSC_ERR_ARG_WRONGSTATE, "Operation not supported on scaled matrix");
424:   }

426:   if (shell->ops->diagonalset) {
427:     (*shell->ops->diagonalset)(A,D,ins);
428:   }
429:   shell->vshift = 0.0;
430:   if (shell->dshift) { VecZeroEntries(shell->dshift); }
431:   return(0);
432: }

434: PetscErrorCode MatScale_Shell(Mat Y,PetscScalar a)
435: {
436:   Mat_Shell      *shell = (Mat_Shell*)Y->data;

440:   shell->vscale *= a;
441:   if (shell->dshift) {
442:     VecScale(shell->dshift,a);
443:   } else shell->vshift *= a;
444:   MatShellUseScaledMethods(Y);
445:   return(0);
446: }

448: static PetscErrorCode MatDiagonalScale_Shell(Mat Y,Vec left,Vec right)
449: {
450:   Mat_Shell      *shell = (Mat_Shell*)Y->data;

454:   if (left) {
455:     if (!shell->left_owned) {VecDuplicate(left,&shell->left_owned);}
456:     if (shell->left) {
457:       VecPointwiseMult(shell->left,shell->left,left);
458:     } else {
459:       shell->left = shell->left_owned;
460:       VecCopy(left,shell->left);
461:     }
462:   }
463:   if (right) {
464:     if (!shell->right_owned) {VecDuplicate(right,&shell->right_owned);}
465:     if (shell->right) {
466:       VecPointwiseMult(shell->right,shell->right,right);
467:     } else {
468:       shell->right = shell->right_owned;
469:       VecCopy(right,shell->right);
470:     }
471:   }
472:   MatShellUseScaledMethods(Y);
473:   return(0);
474: }

476: PetscErrorCode MatAssemblyEnd_Shell(Mat Y,MatAssemblyType t)
477: {
478:   Mat_Shell *shell = (Mat_Shell*)Y->data;

481:   if (t == MAT_FINAL_ASSEMBLY) {
482:     shell->vshift = 0.0;
483:     shell->vscale = 1.0;
484:     shell->dshift = NULL;
485:     shell->left   = NULL;
486:     shell->right  = NULL;
487:     if (shell->ops->mult) {
488:       Y->ops->mult = shell->ops->mult;
489:       shell->ops->mult  = NULL;
490:     }
491:     if (shell->ops->multtranspose) {
492:       Y->ops->multtranspose = shell->ops->multtranspose;
493:       shell->ops->multtranspose = NULL;
494:     }
495:     if (shell->ops->getdiagonal) {
496:       Y->ops->getdiagonal = shell->ops->getdiagonal;
497:       shell->ops->getdiagonal = NULL;
498:     }
499:     if (shell->ops->copy) {
500:       Y->ops->copy = shell->ops->copy;
501:       shell->ops->copy = NULL;
502:     }
503:     shell->usingscaled = PETSC_FALSE;
504:   }
505:   return(0);
506: }

508: PETSC_INTERN PetscErrorCode MatConvert_Shell(Mat, MatType,MatReuse,Mat*);

510: static PetscErrorCode MatMissingDiagonal_Shell(Mat A,PetscBool  *missing,PetscInt *d)
511: {
513:   *missing = PETSC_FALSE;
514:   return(0);
515: }

517: static struct _MatOps MatOps_Values = {0,
518:                                        0,
519:                                        0,
520:                                        0,
521:                                 /* 4*/ 0,
522:                                        0,
523:                                        0,
524:                                        0,
525:                                        0,
526:                                        0,
527:                                 /*10*/ 0,
528:                                        0,
529:                                        0,
530:                                        0,
531:                                        0,
532:                                 /*15*/ 0,
533:                                        0,
534:                                        0,
535:                                        MatDiagonalScale_Shell,
536:                                        0,
537:                                 /*20*/ 0,
538:                                        MatAssemblyEnd_Shell,
539:                                        0,
540:                                        0,
541:                                 /*24*/ 0,
542:                                        0,
543:                                        0,
544:                                        0,
545:                                        0,
546:                                 /*29*/ 0,
547:                                        0,
548:                                        0,
549:                                        0,
550:                                        0,
551:                                 /*34*/ 0,
552:                                        0,
553:                                        0,
554:                                        0,
555:                                        0,
556:                                 /*39*/ 0,
557:                                        0,
558:                                        0,
559:                                        0,
560:                                        0,
561:                                 /*44*/ 0,
562:                                        MatScale_Shell,
563:                                        MatShift_Shell,
564:                                        MatDiagonalSet_Shell,
565:                                        0,
566:                                 /*49*/ 0,
567:                                        0,
568:                                        0,
569:                                        0,
570:                                        0,
571:                                 /*54*/ 0,
572:                                        0,
573:                                        0,
574:                                        0,
575:                                        0,
576:                                 /*59*/ 0,
577:                                        MatDestroy_Shell,
578:                                        0,
579:                                        0,
580:                                        0,
581:                                 /*64*/ 0,
582:                                        0,
583:                                        0,
584:                                        0,
585:                                        0,
586:                                 /*69*/ 0,
587:                                        0,
588:                                        MatConvert_Shell,
589:                                        0,
590:                                        0,
591:                                 /*74*/ 0,
592:                                        0,
593:                                        0,
594:                                        0,
595:                                        0,
596:                                 /*79*/ 0,
597:                                        0,
598:                                        0,
599:                                        0,
600:                                        0,
601:                                 /*84*/ 0,
602:                                        0,
603:                                        0,
604:                                        0,
605:                                        0,
606:                                 /*89*/ 0,
607:                                        0,
608:                                        0,
609:                                        0,
610:                                        0,
611:                                 /*94*/ 0,
612:                                        0,
613:                                        0,
614:                                        0,
615:                                        0,
616:                                 /*99*/ 0,
617:                                        0,
618:                                        0,
619:                                        0,
620:                                        0,
621:                                /*104*/ 0,
622:                                        0,
623:                                        0,
624:                                        0,
625:                                        0,
626:                                /*109*/ 0,
627:                                        0,
628:                                        0,
629:                                        0,
630:                                        MatMissingDiagonal_Shell,
631:                                /*114*/ 0,
632:                                        0,
633:                                        0,
634:                                        0,
635:                                        0,
636:                                /*119*/ 0,
637:                                        0,
638:                                        0,
639:                                        0,
640:                                        0,
641:                                /*124*/ 0,
642:                                        0,
643:                                        0,
644:                                        0,
645:                                        0,
646:                                /*129*/ 0,
647:                                        0,
648:                                        0,
649:                                        0,
650:                                        0,
651:                                /*134*/ 0,
652:                                        0,
653:                                        0,
654:                                        0,
655:                                        0,
656:                                /*139*/ 0,
657:                                        0,
658:                                        0
659: };

661: /*MC
662:    MATSHELL - MATSHELL = "shell" - A matrix type to be used to define your own matrix type -- perhaps matrix free.

664:   Level: advanced

666: .seealso: MatCreateShell
667: M*/

669: PETSC_EXTERN PetscErrorCode MatCreate_Shell(Mat A)
670: {
671:   Mat_Shell      *b;

675:   PetscMemcpy(A->ops,&MatOps_Values,sizeof(struct _MatOps));

677:   PetscNewLog(A,&b);
678:   A->data = (void*)b;

680:   PetscLayoutSetUp(A->rmap);
681:   PetscLayoutSetUp(A->cmap);

683:   b->ctx           = 0;
684:   b->vshift        = 0.0;
685:   b->vscale        = 1.0;
686:   A->assembled     = PETSC_TRUE;
687:   A->preallocated  = PETSC_FALSE;

689:   PetscObjectChangeTypeName((PetscObject)A,MATSHELL);
690:   return(0);
691: }

693: /*@C
694:    MatCreateShell - Creates a new matrix class for use with a user-defined
695:    private data storage format.

697:   Collective on MPI_Comm

699:    Input Parameters:
700: +  comm - MPI communicator
701: .  m - number of local rows (must be given)
702: .  n - number of local columns (must be given)
703: .  M - number of global rows (may be PETSC_DETERMINE)
704: .  N - number of global columns (may be PETSC_DETERMINE)
705: -  ctx - pointer to data needed by the shell matrix routines

707:    Output Parameter:
708: .  A - the matrix

710:    Level: advanced

712:   Usage:
713: $    extern int mult(Mat,Vec,Vec);
714: $    MatCreateShell(comm,m,n,M,N,ctx,&mat);
715: $    MatShellSetOperation(mat,MATOP_MULT,(void(*)(void))mult);
716: $    [ Use matrix for operations that have been set ]
717: $    MatDestroy(mat);

719:    Notes:
720:    The shell matrix type is intended to provide a simple class to use
721:    with KSP (such as, for use with matrix-free methods). You should not
722:    use the shell type if you plan to define a complete matrix class.

724:    Fortran Notes: To use this from Fortran with a ctx you must write an interface definition for this
725:     function and for MatShellGetContext() that tells Fortran the Fortran derived data type you are passing
726:     in as the ctx argument.

728:    PETSc requires that matrices and vectors being used for certain
729:    operations are partitioned accordingly.  For example, when
730:    creating a shell matrix, A, that supports parallel matrix-vector
731:    products using MatMult(A,x,y) the user should set the number
732:    of local matrix rows to be the number of local elements of the
733:    corresponding result vector, y. Note that this is information is
734:    required for use of the matrix interface routines, even though
735:    the shell matrix may not actually be physically partitioned.
736:    For example,

738: $
739: $     Vec x, y
740: $     extern int mult(Mat,Vec,Vec);
741: $     Mat A
742: $
743: $     VecCreateMPI(comm,PETSC_DECIDE,M,&y);
744: $     VecCreateMPI(comm,PETSC_DECIDE,N,&x);
745: $     VecGetLocalSize(y,&m);
746: $     VecGetLocalSize(x,&n);
747: $     MatCreateShell(comm,m,n,M,N,ctx,&A);
748: $     MatShellSetOperation(mat,MATOP_MULT,(void(*)(void))mult);
749: $     MatMult(A,x,y);
750: $     MatDestroy(A);
751: $     VecDestroy(y); VecDestroy(x);
752: $

754: .keywords: matrix, shell, create

756: .seealso: MatShellSetOperation(), MatHasOperation(), MatShellGetContext(), MatShellSetContext()
757: @*/
758: PetscErrorCode  MatCreateShell(MPI_Comm comm,PetscInt m,PetscInt n,PetscInt M,PetscInt N,void *ctx,Mat *A)
759: {

763:   MatCreate(comm,A);
764:   MatSetSizes(*A,m,n,M,N);
765:   MatSetType(*A,MATSHELL);
766:   MatShellSetContext(*A,ctx);
767:   MatSetUp(*A);
768:   return(0);
769: }

771: /*@
772:     MatShellSetContext - sets the context for a shell matrix

774:    Logically Collective on Mat

776:     Input Parameters:
777: +   mat - the shell matrix
778: -   ctx - the context

780:    Level: advanced

782:    Fortran Notes: To use this from Fortran you must write a Fortran interface definition for this
783:     function that tells Fortran the Fortran derived data type that you are passing in as the ctx argument.

785: .seealso: MatCreateShell(), MatShellGetContext(), MatShellGetOperation()
786: @*/
787: PetscErrorCode  MatShellSetContext(Mat mat,void *ctx)
788: {
789:   Mat_Shell      *shell = (Mat_Shell*)mat->data;
791:   PetscBool      flg;

795:   PetscObjectTypeCompare((PetscObject)mat,MATSHELL,&flg);
796:   if (flg) {
797:     shell->ctx = ctx;
798:   } else SETERRQ(PetscObjectComm((PetscObject)mat),PETSC_ERR_SUP,"Cannot attach context to non-shell matrix");
799:   return(0);
800: }

802: /*@C
803:     MatShellSetOperation - Allows user to set a matrix operation for
804:                            a shell matrix.

806:    Logically Collective on Mat

808:     Input Parameters:
809: +   mat - the shell matrix
810: .   op - the name of the operation
811: -   f - the function that provides the operation.

813:    Level: advanced

815:     Usage:
816: $      extern PetscErrorCode usermult(Mat,Vec,Vec);
817: $      MatCreateShell(comm,m,n,M,N,ctx,&A);
818: $      MatShellSetOperation(A,MATOP_MULT,(void(*)(void))usermult);

820:     Notes:
821:     See the file include/petscmat.h for a complete list of matrix
822:     operations, which all have the form MATOP_<OPERATION>, where
823:     <OPERATION> is the name (in all capital letters) of the
824:     user interface routine (e.g., MatMult() -> MATOP_MULT).

826:     All user-provided functions (execept for MATOP_DESTROY) should have the same calling
827:     sequence as the usual matrix interface routines, since they
828:     are intended to be accessed via the usual matrix interface
829:     routines, e.g.,
830: $       MatMult(Mat,Vec,Vec) -> usermult(Mat,Vec,Vec)

832:     In particular each function MUST return an error code of 0 on success and
833:     nonzero on failure.

835:     Within each user-defined routine, the user should call
836:     MatShellGetContext() to obtain the user-defined context that was
837:     set by MatCreateShell().

839:     Fortran Notes: For MatCreateVecs() the user code should check if the input left or right matrix is -1 and in that case not
840:        generate a matrix. See src/mat/examples/tests/ex120f.F

842: .keywords: matrix, shell, set, operation

844: .seealso: MatCreateShell(), MatShellGetContext(), MatShellGetOperation(), MatShellSetContext()
845: @*/
846: PetscErrorCode  MatShellSetOperation(Mat mat,MatOperation op,void (*f)(void))
847: {
849:   PetscBool      flg;

853:   switch (op) {
854:   case MATOP_DESTROY:
855:     PetscObjectTypeCompare((PetscObject)mat,MATSHELL,&flg);
856:     if (flg) {
857:       Mat_Shell *shell = (Mat_Shell*)mat->data;
858:       shell->ops->destroy = (PetscErrorCode (*)(Mat))f;
859:     } else mat->ops->destroy = (PetscErrorCode (*)(Mat))f;
860:     break;
861:   case MATOP_DIAGONAL_SET:
862:     PetscObjectTypeCompare((PetscObject)mat,MATSHELL,&flg);
863:     if (flg) {
864:       Mat_Shell *shell = (Mat_Shell*)mat->data;
865:       shell->ops->diagonalset = (PetscErrorCode (*)(Mat,Vec,InsertMode))f;
866:     } else {
867:       mat->ops->diagonalset = (PetscErrorCode (*)(Mat,Vec,InsertMode))f;
868:     }
869:     break;
870:   case MATOP_VIEW:
871:     mat->ops->view = (PetscErrorCode (*)(Mat,PetscViewer))f;
872:     break;
873:   case MATOP_MULT:
874:     mat->ops->mult = (PetscErrorCode (*)(Mat,Vec,Vec))f;
875:     if (!mat->ops->multadd) mat->ops->multadd = MatMultAdd_Shell;
876:     break;
877:   case MATOP_MULT_TRANSPOSE:
878:     mat->ops->multtranspose = (PetscErrorCode (*)(Mat,Vec,Vec))f;
879:     if (!mat->ops->multtransposeadd) mat->ops->multtransposeadd = MatMultTransposeAdd_Shell;
880:     break;
881:   default:
882:     (((void(**)(void))mat->ops)[op]) = f;
883:   }
884:   return(0);
885: }

887: /*@C
888:     MatShellGetOperation - Gets a matrix function for a shell matrix.

890:     Not Collective

892:     Input Parameters:
893: +   mat - the shell matrix
894: -   op - the name of the operation

896:     Output Parameter:
897: .   f - the function that provides the operation.

899:     Level: advanced

901:     Notes:
902:     See the file include/petscmat.h for a complete list of matrix
903:     operations, which all have the form MATOP_<OPERATION>, where
904:     <OPERATION> is the name (in all capital letters) of the
905:     user interface routine (e.g., MatMult() -> MATOP_MULT).

907:     All user-provided functions have the same calling
908:     sequence as the usual matrix interface routines, since they
909:     are intended to be accessed via the usual matrix interface
910:     routines, e.g.,
911: $       MatMult(Mat,Vec,Vec) -> usermult(Mat,Vec,Vec)

913:     Within each user-defined routine, the user should call
914:     MatShellGetContext() to obtain the user-defined context that was
915:     set by MatCreateShell().

917: .keywords: matrix, shell, set, operation

919: .seealso: MatCreateShell(), MatShellGetContext(), MatShellSetOperation(), MatShellSetContext()
920: @*/
921: PetscErrorCode  MatShellGetOperation(Mat mat,MatOperation op,void(**f)(void))
922: {
924:   PetscBool      flg;

928:   switch (op) {
929:   case MATOP_DESTROY:
930:     PetscObjectTypeCompare((PetscObject)mat,MATSHELL,&flg);
931:     if (flg) {
932:       Mat_Shell *shell = (Mat_Shell*)mat->data;
933:       *f = (void (*)(void))shell->ops->destroy;
934:     } else {
935:       *f = (void (*)(void))mat->ops->destroy;
936:     }
937:     break;
938:   case MATOP_DIAGONAL_SET:
939:     PetscObjectTypeCompare((PetscObject)mat,MATSHELL,&flg);
940:     if (flg) {
941:       Mat_Shell *shell = (Mat_Shell*)mat->data;
942:       *f = (void (*)(void))shell->ops->diagonalset;
943:     } else {
944:       *f = (void (*)(void))mat->ops->diagonalset;
945:     }
946:     break;
947:   case MATOP_VIEW:
948:     *f = (void (*)(void))mat->ops->view;
949:     break;
950:   default:
951:     *f = (((void (**)(void))mat->ops)[op]);
952:   }
953:   return(0);
954: }