Actual source code: stag1d.c

  1: /*
  2:    Functions specific to the 1-dimensional implementation of DMStag
  3: */
  4: #include <petsc/private/dmstagimpl.h>

  6: /*@C
  7:   DMStagCreate1d - Create an object to manage data living on the elements and vertices of a parallelized regular 1D grid.

  9:   Collective

 11:   Input Parameters:
 12: + comm - MPI communicator
 13: . bndx - boundary type: DM_BOUNDARY_NONE, DM_BOUNDARY_PERIODIC, or DM_BOUNDARY_GHOSTED
 14: . M - global number of grid points
 15: . dof0 - number of degrees of freedom per vertex/0-cell
 16: . dof1 - number of degrees of freedom per element/1-cell
 17: . stencilType - ghost/halo region type: DMSTAG_STENCIL_BOX or DMSTAG_STENCIL_NONE
 18: . stencilWidth - width, in elements, of halo/ghost region
 19: - lx - array of local sizes, of length equal to the comm size, summing to M

 21:   Output Parameter:
 22: . dm - the new DMStag object

 24:   Options Database Keys:
 25: + -dm_view - calls DMViewFromOptions() a the conclusion of DMSetUp()
 26: . -stag_grid_x <nx> - number of elements in the x direction
 27: . -stag_ghost_stencil_width - width of ghost region, in elements
 28: - -stag_boundary_type_x <none,ghosted,periodic> - DMBoundaryType value

 30:   Notes:
 31:   You must call DMSetUp() after this call before using the DM.
 32:   If you wish to use the options database (see the keys above) to change values in the DMStag, you must call
 33:   DMSetFromOptions() after this function but before DMSetUp().

 35:   Level: beginner

 37: .seealso: DMSTAG, DMStagCreate2d(), DMStagCreate3d(), DMDestroy(), DMView(), DMCreateGlobalVector(), DMCreateLocalVector(), DMLocalToGlobalBegin(), DMDACreate1d()
 38: @*/
 39: PETSC_EXTERN PetscErrorCode DMStagCreate1d(MPI_Comm comm,DMBoundaryType bndx,PetscInt M,PetscInt dof0,PetscInt dof1,DMStagStencilType stencilType,PetscInt stencilWidth,const PetscInt lx[],DM* dm)
 40: {
 41:   PetscMPIInt    size;

 43:   MPI_Comm_size(comm,&size);
 44:   DMCreate(comm,dm);
 45:   DMSetDimension(*dm,1);
 46:   DMStagInitialize(bndx,DM_BOUNDARY_NONE,DM_BOUNDARY_NONE,M,0,0,size,0,0,dof0,dof1,0,0,stencilType,stencilWidth,lx,NULL,NULL,*dm);
 47:   return 0;
 48: }

 50: PETSC_INTERN PetscErrorCode DMStagSetUniformCoordinatesExplicit_1d(DM dm,PetscReal xmin,PetscReal xmax)
 51: {
 52:   DM_Stag        *stagCoord;
 53:   DM             dmCoord;
 54:   Vec            coordLocal;
 55:   PetscReal      h,min;
 56:   PetscScalar    **arr;
 57:   PetscInt       start_ghost,n_ghost,s;
 58:   PetscInt       ileft,ielement;

 60:   DMGetCoordinateDM(dm, &dmCoord);
 61:   stagCoord = (DM_Stag*) dmCoord->data;
 62:   for (s=0; s<2; ++s) {
 64:   }
 65:   DMCreateLocalVector(dmCoord,&coordLocal);

 67:   DMStagVecGetArray(dmCoord,coordLocal,&arr);
 68:   if (stagCoord->dof[0]) {
 69:     DMStagGetLocationSlot(dmCoord,DMSTAG_LEFT,0,&ileft);
 70:   }
 71:   if (stagCoord->dof[1]) {
 72:     DMStagGetLocationSlot(dmCoord,DMSTAG_ELEMENT,0,&ielement);
 73:   }
 74:   DMStagGetGhostCorners(dmCoord,&start_ghost,NULL,NULL,&n_ghost,NULL,NULL);

 76:   min = xmin;
 77:   h = (xmax-xmin)/stagCoord->N[0];

 79:   for (PetscInt ind=start_ghost; ind<start_ghost + n_ghost; ++ind) {
 80:     if (stagCoord->dof[0]) {
 81:       const PetscReal off = 0.0;
 82:         arr[ind][ileft] = min + ((PetscReal)ind + off) * h;
 83:     }
 84:     if (stagCoord->dof[1]) {
 85:       const PetscReal off = 0.5;
 86:         arr[ind][ielement] = min + ((PetscReal)ind + off) * h;
 87:     }
 88:   }
 89:   DMStagVecRestoreArray(dmCoord,coordLocal,&arr);
 90:   DMSetCoordinatesLocal(dm,coordLocal);
 91:   PetscLogObjectParent((PetscObject)dm,(PetscObject)coordLocal);
 92:   VecDestroy(&coordLocal);
 93:   return 0;
 94: }

 96: /* Helper functions used in DMSetUp_Stag() */
 97: static PetscErrorCode DMStagComputeLocationOffsets_1d(DM);

 99: PETSC_INTERN PetscErrorCode DMSetUp_Stag_1d(DM dm)
100: {
101:   DM_Stag * const stag = (DM_Stag*)dm->data;
102:   PetscMPIInt     size,rank;
103:   MPI_Comm        comm;
104:   PetscInt        j;

106:   PetscObjectGetComm((PetscObject)dm,&comm);
107:   MPI_Comm_size(comm,&size);
108:   MPI_Comm_rank(comm,&rank);

110:   /* Check Global size */

113:   /* Local sizes */
115:   if (!stag->l[0]) {
116:     /* Divide equally, giving an extra elements to higher ranks */
117:     PetscMalloc1(stag->nRanks[0],&stag->l[0]);
118:     for (j=0; j<stag->nRanks[0]; ++j) stag->l[0][j] = stag->N[0]/stag->nRanks[0] + (stag->N[0] % stag->nRanks[0] > j ? 1 : 0);
119:   }
120:   {
121:     PetscInt Nchk = 0;
122:     for (j=0; j<size; ++j) Nchk += stag->l[0][j];
124:   }
125:   stag->n[0] = stag->l[0][rank];

127:   /* Rank (trivial in 1d) */
128:   stag->rank[0]      = rank;
129:   stag->firstRank[0] = (PetscBool)(rank == 0);
130:   stag->lastRank[0]  = (PetscBool)(rank == size-1);

132:   /* Local (unghosted) numbers of entries */
133:   stag->entriesPerElement = stag->dof[0] + stag->dof[1];
134:   switch (stag->boundaryType[0]) {
135:     case DM_BOUNDARY_NONE:
136:     case DM_BOUNDARY_GHOSTED:  stag->entries = stag->n[0] * stag->entriesPerElement + (stag->lastRank[0] ?  stag->dof[0] : 0); break;
137:     case DM_BOUNDARY_PERIODIC: stag->entries = stag->n[0] * stag->entriesPerElement;                                           break;
138:     default: SETERRQ(PetscObjectComm((PetscObject)dm),PETSC_ERR_SUP,"Unsupported x boundary type %s",DMBoundaryTypes[stag->boundaryType[0]]);
139:   }

141:   /* Starting element */
142:   stag->start[0] = 0;
143:   for (j=0; j<stag->rank[0]; ++j) stag->start[0] += stag->l[0][j];

145:   /* Local/ghosted size and starting element */
146:   switch (stag->boundaryType[0]) {
147:     case DM_BOUNDARY_NONE :
148:       switch (stag->stencilType) {
149:         case DMSTAG_STENCIL_NONE : /* Only dummy cells on the right */
150:           stag->startGhost[0] = stag->start[0];
151:           stag->nGhost[0]     = stag->n[0] + (stag->lastRank[0] ? 1 : 0);
152:           break;
153:         case DMSTAG_STENCIL_STAR :
154:         case DMSTAG_STENCIL_BOX :
155:           stag->startGhost[0] = stag->firstRank[0] ? stag->start[0]: stag->start[0] - stag->stencilWidth;
156:           stag->nGhost[0] = stag->n[0];
157:           stag->nGhost[0] += stag->firstRank[0] ? 0 : stag->stencilWidth;
158:           stag->nGhost[0] += stag->lastRank[0]  ? 1 : stag->stencilWidth;
159:           break;
160:         default :
161:           SETERRQ(PetscObjectComm((PetscObject)dm),PETSC_ERR_SUP,"Unrecognized ghost stencil type %d",stag->stencilType);
162:       }
163:       break;
164:     case DM_BOUNDARY_GHOSTED:
165:       switch (stag->stencilType) {
166:         case DMSTAG_STENCIL_NONE :
167:           stag->startGhost[0] = stag->start[0];
168:           stag->nGhost[0]     = stag->n[0] + (stag->lastRank[0] ? 1 : 0);
169:           break;
170:         case DMSTAG_STENCIL_STAR :
171:         case DMSTAG_STENCIL_BOX :
172:           stag->startGhost[0] = stag->start[0] - stag->stencilWidth; /* This value may be negative */
173:           stag->nGhost[0]     = stag->n[0] + 2*stag->stencilWidth + (stag->lastRank[0] && stag->stencilWidth == 0 ? 1 : 0);
174:           break;
175:         default :
176:           SETERRQ(PetscObjectComm((PetscObject)dm),PETSC_ERR_SUP,"Unrecognized ghost stencil type %d",stag->stencilType);
177:       }
178:       break;
179:     case DM_BOUNDARY_PERIODIC:
180:       switch (stag->stencilType) {
181:         case DMSTAG_STENCIL_NONE :
182:           stag->startGhost[0] = stag->start[0];
183:           stag->nGhost[0]     = stag->n[0];
184:           break;
185:         case DMSTAG_STENCIL_STAR :
186:         case DMSTAG_STENCIL_BOX :
187:           stag->startGhost[0] = stag->start[0] - stag->stencilWidth; /* This value may be negative */
188:           stag->nGhost[0]     = stag->n[0] + 2*stag->stencilWidth;
189:           break;
190:         default :
191:           SETERRQ(PetscObjectComm((PetscObject)dm),PETSC_ERR_SUP,"Unrecognized ghost stencil type %d",stag->stencilType);
192:       }
193:       break;
194:     default :
195:       SETERRQ(PetscObjectComm((PetscObject)dm),PETSC_ERR_SUP,"Unsupported x boundary type %s",DMBoundaryTypes[stag->boundaryType[0]]);
196:   }

198:   /* Total size of ghosted/local representation */
199:   stag->entriesGhost = stag->nGhost[0]*stag->entriesPerElement;

201:   /* Define neighbors */
202:   PetscMalloc1(3,&stag->neighbors);
203:   if (stag->firstRank[0]) {
204:     switch (stag->boundaryType[0]) {
205:       case DM_BOUNDARY_GHOSTED:
206:       case DM_BOUNDARY_NONE:     stag->neighbors[0] = -1;                break;
207:       case DM_BOUNDARY_PERIODIC: stag->neighbors[0] = stag->nRanks[0]-1; break;
208:       default : SETERRQ(PetscObjectComm((PetscObject)dm),PETSC_ERR_SUP,"Unsupported x boundary type %s",DMBoundaryTypes[stag->boundaryType[0]]);
209:     }
210:   } else {
211:     stag->neighbors[0] = stag->rank[0]-1;
212:   }
213:   stag->neighbors[1] = stag->rank[0];
214:   if (stag->lastRank[0]) {
215:     switch (stag->boundaryType[0]) {
216:       case DM_BOUNDARY_GHOSTED:
217:       case DM_BOUNDARY_NONE:     stag->neighbors[2] = -1;                break;
218:       case DM_BOUNDARY_PERIODIC: stag->neighbors[2] = 0;                 break;
219:       default : SETERRQ(PetscObjectComm((PetscObject)dm),PETSC_ERR_SUP,"Unsupported x boundary type %s",DMBoundaryTypes[stag->boundaryType[0]]);
220:     }
221:   } else {
222:     stag->neighbors[2] = stag->rank[0]+1;
223:   }

225:   if (stag->n[0] < stag->stencilWidth) {
226:     SETERRQ(PETSC_COMM_SELF,PETSC_ERR_SUP,"DMStag 1d setup does not support local sizes (%d) smaller than the elementwise stencil width (%d)",stag->n[0],stag->stencilWidth);
227:   }

229:   /* Create global->local VecScatter and ISLocalToGlobalMapping */
230:   {
231:     PetscInt *idxLocal,*idxGlobal,*idxGlobalAll;
232:     PetscInt i,iLocal,d,entriesToTransferTotal,ghostOffsetStart,ghostOffsetEnd,nNonDummyGhost;
233:     IS       isLocal,isGlobal;

235:     /* The offset on the right (may not be equal to the stencil width, as we
236:        always have at least one ghost element, to account for the boundary
237:        point, and may with ghosted boundaries), and the number of non-dummy ghost elements */
238:     ghostOffsetStart = stag->start[0] - stag->startGhost[0];
239:     ghostOffsetEnd   = stag->startGhost[0]+stag->nGhost[0] - (stag->start[0]+stag->n[0]);
240:     nNonDummyGhost   = stag->nGhost[0] - (stag->lastRank[0] ? ghostOffsetEnd : 0) - (stag->firstRank[0] ? ghostOffsetStart : 0);

242:     /* Compute the number of non-dummy entries in the local representation
243:        This is equal to the number of non-dummy elements in the local (ghosted) representation,
244:        plus some extra entries on the right boundary on the last rank*/
245:     switch (stag->boundaryType[0]) {
246:       case DM_BOUNDARY_GHOSTED:
247:       case DM_BOUNDARY_NONE:
248:         entriesToTransferTotal = nNonDummyGhost * stag->entriesPerElement + (stag->lastRank[0] ? stag->dof[0] : 0);
249:         break;
250:       case DM_BOUNDARY_PERIODIC:
251:         entriesToTransferTotal = stag->entriesGhost; /* No dummy points */
252:         break;
253:       default :
254:         SETERRQ(PetscObjectComm((PetscObject)dm),PETSC_ERR_SUP,"Unsupported x boundary type %s",DMBoundaryTypes[stag->boundaryType[0]]);
255:     }

257:     PetscMalloc1(entriesToTransferTotal,&idxLocal);
258:     PetscMalloc1(entriesToTransferTotal,&idxGlobal);
259:     PetscMalloc1(stag->entriesGhost,&idxGlobalAll);
260:     if (stag->boundaryType[0] == DM_BOUNDARY_NONE) {
261:       PetscInt count = 0,countAll = 0;
262:       /* Left ghost points and native points */
263:       for (i=stag->startGhost[0], iLocal=0; iLocal<nNonDummyGhost; ++i,++iLocal) {
264:         for (d=0; d<stag->entriesPerElement; ++d,++count,++countAll) {
265:           idxLocal [count]       = iLocal * stag->entriesPerElement + d;
266:           idxGlobal[count]       = i      * stag->entriesPerElement + d;
267:           idxGlobalAll[countAll] = i      * stag->entriesPerElement + d;
268:         }
269:       }
270:       /* Ghost points on the right
271:          Special case for last (partial dummy) element on the last rank */
272:       if (stag->lastRank[0]) {
273:         i      = stag->N[0];
274:         iLocal = (stag->nGhost[0]-ghostOffsetEnd);
275:         /* Only vertex (0-cell) dofs in global representation */
276:         for (d=0; d<stag->dof[0]; ++d,++count,++countAll) {
277:           idxGlobal[count]       = i      * stag->entriesPerElement + d;
278:           idxLocal [count]       = iLocal * stag->entriesPerElement + d;
279:           idxGlobalAll[countAll] = i      * stag->entriesPerElement + d;
280:         }
281:         for (d=stag->dof[0]; d<stag->entriesPerElement; ++d,++countAll) { /* Additional dummy entries */
282:           idxGlobalAll[countAll] = -1;
283:         }
284:       }
285:     } else if (stag->boundaryType[0] == DM_BOUNDARY_PERIODIC) {
286:       PetscInt count = 0,iLocal = 0; /* No dummy points, so idxGlobal and idxGlobalAll are identical */
287:       const PetscInt iMin = stag->firstRank[0] ? stag->start[0] : stag->startGhost[0];
288:       const PetscInt iMax = stag->lastRank[0] ? stag->startGhost[0] + stag->nGhost[0] - stag->stencilWidth : stag->startGhost[0] + stag->nGhost[0];
289:       /* Ghost points on the left */
290:       if (stag->firstRank[0]) {
291:         for (i=stag->N[0]-stag->stencilWidth; iLocal<stag->stencilWidth; ++i,++iLocal) {
292:           for (d=0; d<stag->entriesPerElement; ++d,++count) {
293:             idxGlobal[count] = i      * stag->entriesPerElement + d;
294:             idxLocal [count] = iLocal * stag->entriesPerElement + d;
295:             idxGlobalAll[count] = idxGlobal[count];
296:           }
297:         }
298:       }
299:       /* Native points */
300:       for (i=iMin; i<iMax; ++i,++iLocal) {
301:         for (d=0; d<stag->entriesPerElement; ++d,++count) {
302:           idxGlobal[count] = i      * stag->entriesPerElement + d;
303:           idxLocal [count] = iLocal * stag->entriesPerElement + d;
304:           idxGlobalAll[count] = idxGlobal[count];
305:         }
306:       }
307:       /* Ghost points on the right */
308:       if (stag->lastRank[0]) {
309:         for (i=0; iLocal<stag->nGhost[0]; ++i,++iLocal) {
310:           for (d=0; d<stag->entriesPerElement; ++d,++count) {
311:             idxGlobal[count] = i      * stag->entriesPerElement + d;
312:             idxLocal [count] = iLocal * stag->entriesPerElement + d;
313:             idxGlobalAll[count] = idxGlobal[count];
314:           }
315:         }
316:       }
317:     } else if (stag->boundaryType[0] == DM_BOUNDARY_GHOSTED) {
318:       PetscInt count = 0,countAll = 0;
319:       /* Dummy elements on the left, on the first rank */
320:       if (stag->firstRank[0]) {
321:         for (iLocal=0; iLocal<ghostOffsetStart; ++iLocal) {
322:           /* Complete elements full of dummy entries */
323:           for (d=0; d<stag->entriesPerElement; ++d,++countAll) {
324:             idxGlobalAll[countAll] = -1;
325:           }
326:         }
327:         i = 0; /* nonDummy entries start with global entry 0 */
328:       } else {
329:         /* nonDummy entries start as usual */
330:         i = stag->startGhost[0];
331:         iLocal = 0;
332:       }

334:       /* non-Dummy entries */
335:       {
336:         PetscInt iLocalNonDummyMax = stag->firstRank[0] ? nNonDummyGhost + ghostOffsetStart : nNonDummyGhost;
337:         for (; iLocal<iLocalNonDummyMax; ++i,++iLocal) {
338:           for (d=0; d<stag->entriesPerElement; ++d,++count,++countAll) {
339:             idxLocal [count]       = iLocal * stag->entriesPerElement + d;
340:             idxGlobal[count]       = i      * stag->entriesPerElement + d;
341:             idxGlobalAll[countAll] = i      * stag->entriesPerElement + d;
342:           }
343:         }
344:       }

346:       /* (partial) dummy elements on the right, on the last rank */
347:       if (stag->lastRank[0]) {
348:         /* First one is partial dummy */
349:         i      = stag->N[0];
350:         iLocal = (stag->nGhost[0]-ghostOffsetEnd);
351:         for (d=0; d<stag->dof[0]; ++d,++count,++countAll) { /* Only vertex (0-cell) dofs in global representation */
352:           idxLocal [count]       = iLocal * stag->entriesPerElement + d;
353:           idxGlobal[count]       = i      * stag->entriesPerElement + d;
354:           idxGlobalAll[countAll] = i      * stag->entriesPerElement + d;
355:         }
356:         for (d=stag->dof[0]; d<stag->entriesPerElement; ++d,++countAll) { /* Additional dummy entries */
357:           idxGlobalAll[countAll] = -1;
358:         }
359:         for (iLocal = stag->nGhost[0] - ghostOffsetEnd + 1; iLocal < stag->nGhost[0]; ++iLocal) {
360:           /* Additional dummy elements */
361:           for (d=0; d<stag->entriesPerElement; ++d,++countAll) {
362:             idxGlobalAll[countAll] = -1;
363:           }
364:         }
365:       }
366:     } else SETERRQ(PetscObjectComm((PetscObject)dm),PETSC_ERR_SUP,"Unsupported x boundary type %s",DMBoundaryTypes[stag->boundaryType[0]]);

368:     /* Create Local IS (transferring pointer ownership) */
369:     ISCreateGeneral(PetscObjectComm((PetscObject)dm),entriesToTransferTotal,idxLocal,PETSC_OWN_POINTER,&isLocal);

371:     /* Create Global IS (transferring pointer ownership) */
372:     ISCreateGeneral(PetscObjectComm((PetscObject)dm),entriesToTransferTotal,idxGlobal,PETSC_OWN_POINTER,&isGlobal);

374:     /* Create stag->gtol, which doesn't include dummy entries */
375:     {
376:       Vec local,global;
377:       VecCreateMPIWithArray(PetscObjectComm((PetscObject)dm),1,stag->entries,PETSC_DECIDE,NULL,&global);
378:       VecCreateSeqWithArray(PETSC_COMM_SELF,stag->entriesPerElement,stag->entriesGhost,NULL,&local);
379:       VecScatterCreate(global,isGlobal,local,isLocal,&stag->gtol);
380:       VecDestroy(&global);
381:       VecDestroy(&local);
382:     }

384:     /* In special cases, create a dedicated injective local-to-global map */
385:     if (stag->boundaryType[0] == DM_BOUNDARY_PERIODIC && stag->nRanks[0] == 1) {
386:       DMStagPopulateLocalToGlobalInjective(dm);
387:     }

389:     /* Destroy ISs */
390:     ISDestroy(&isLocal);
391:     ISDestroy(&isGlobal);

393:     /* Create local-to-global map (transferring pointer ownership) */
394:     ISLocalToGlobalMappingCreate(comm,1,stag->entriesGhost,idxGlobalAll,PETSC_OWN_POINTER,&dm->ltogmap);
395:     PetscLogObjectParent((PetscObject)dm,(PetscObject)dm->ltogmap);
396:   }

398:   /* Precompute location offsets */
399:   DMStagComputeLocationOffsets_1d(dm);

401:   /* View from Options */
402:   DMViewFromOptions(dm,NULL,"-dm_view");

404:  return 0;
405: }

407: static PetscErrorCode DMStagComputeLocationOffsets_1d(DM dm)
408: {
409:   DM_Stag * const stag = (DM_Stag*)dm->data;
410:   const PetscInt  epe = stag->entriesPerElement;

412:   PetscMalloc1(DMSTAG_NUMBER_LOCATIONS,&stag->locationOffsets);
413:   stag->locationOffsets[DMSTAG_LEFT]    = 0;
414:   stag->locationOffsets[DMSTAG_ELEMENT] = stag->locationOffsets[DMSTAG_LEFT] + stag->dof[0];
415:   stag->locationOffsets[DMSTAG_RIGHT]   = stag->locationOffsets[DMSTAG_LEFT] + epe;
416:   return 0;
417: }

419: PETSC_INTERN PetscErrorCode DMStagPopulateLocalToGlobalInjective_1d(DM dm)
420: {
421:   DM_Stag * const stag = (DM_Stag*)dm->data;
422:   PetscInt        *idxLocal,*idxGlobal;
423:   PetscInt        i,iLocal,d,count;
424:   IS              isLocal,isGlobal;

426:   PetscMalloc1(stag->entries,&idxLocal);
427:   PetscMalloc1(stag->entries,&idxGlobal);
428:   count = 0;
429:   iLocal = stag->start[0]-stag->startGhost[0];
430:   for (i=stag->start[0]; i<stag->start[0]+stag->n[0]; ++i,++iLocal) {
431:     for (d=0; d<stag->entriesPerElement; ++d,++count) {
432:       idxGlobal[count] = i      * stag->entriesPerElement + d;
433:       idxLocal [count] = iLocal * stag->entriesPerElement + d;
434:     }
435:   }
436:   if (stag->lastRank[0] && stag->boundaryType[0] != DM_BOUNDARY_PERIODIC) {
437:     i = stag->start[0]+stag->n[0];
438:     iLocal = stag->start[0]-stag->startGhost[0] + stag->n[0];
439:     for (d=0; d<stag->dof[0]; ++d,++count) {
440:       idxGlobal[count] = i      * stag->entriesPerElement + d;
441:       idxLocal [count] = iLocal * stag->entriesPerElement + d;
442:     }
443:   }
444:   ISCreateGeneral(PetscObjectComm((PetscObject)dm),stag->entries,idxLocal,PETSC_OWN_POINTER,&isLocal);
445:   ISCreateGeneral(PetscObjectComm((PetscObject)dm),stag->entries,idxGlobal,PETSC_OWN_POINTER,&isGlobal);
446:   {
447:     Vec local,global;
448:     VecCreateMPIWithArray(PetscObjectComm((PetscObject)dm),1,stag->entries,PETSC_DECIDE,NULL,&global);
449:     VecCreateSeqWithArray(PETSC_COMM_SELF,stag->entriesPerElement,stag->entriesGhost,NULL,&local);
450:     VecScatterCreate(local,isLocal,global,isGlobal,&stag->ltog_injective);
451:     VecDestroy(&global);
452:     VecDestroy(&local);
453:   }
454:   ISDestroy(&isLocal);
455:   ISDestroy(&isGlobal);
456:   return 0;
457: }

459: PETSC_INTERN PetscErrorCode DMCreateMatrix_Stag_1D_AIJ_Assemble(DM dm,Mat A)
460: {
461:   DMStagStencilType stencil_type;
462:   PetscInt          dof[2],start,n,n_extra,stencil_width,N,epe;
463:   DMBoundaryType    boundary_type_x;

465:   DMStagGetDOF(dm,&dof[0],&dof[1],NULL,NULL);
466:   DMStagGetStencilType(dm,&stencil_type);
467:   DMStagGetStencilWidth(dm,&stencil_width);
468:   DMStagGetCorners(dm,&start,NULL,NULL,&n,NULL,NULL,&n_extra,NULL,NULL);
469:   DMStagGetGlobalSizes(dm,&N,NULL,NULL);
470:   DMStagGetEntriesPerElement(dm,&epe);
471:   DMStagGetBoundaryTypes(dm,&boundary_type_x,NULL,NULL);
472:   if (stencil_type == DMSTAG_STENCIL_NONE) {
473:     /* Couple all DOF at each location to each other */
474:     DMStagStencil *row_vertex,*row_element;

476:     PetscMalloc1(dof[0],&row_vertex);
477:     for (PetscInt c=0; c<dof[0]; ++c) {
478:       row_vertex[c].loc = DMSTAG_LEFT;
479:       row_vertex[c].c = c;
480:     }

482:     PetscMalloc1(dof[1],&row_element);
483:     for (PetscInt c=0; c<dof[1]; ++c) {
484:       row_element[c].loc = DMSTAG_ELEMENT;
485:       row_element[c].c = c;
486:     }

488:     for (PetscInt e=start; e<start+n+n_extra; ++e) {
489:       {
490:         for (PetscInt c=0; c<dof[0]; ++c){
491:           row_vertex[c].i = e;
492:         }
493:         DMStagMatSetValuesStencil(dm,A,dof[0],row_vertex,dof[0],row_vertex,NULL,INSERT_VALUES);
494:       }
495:       if (e < N) {
496:         for (PetscInt c=0; c<dof[1]; ++c) {
497:           row_element[c].i = e;
498:         }
499:         DMStagMatSetValuesStencil(dm,A,dof[1],row_element,dof[1],row_element,NULL,INSERT_VALUES);
500:       }
501:     }
502:     PetscFree(row_vertex);
503:     PetscFree(row_element);
504:   } else if (stencil_type == DMSTAG_STENCIL_STAR || stencil_type == DMSTAG_STENCIL_BOX) {
505:     DMStagStencil *col,*row;

507:     PetscMalloc1(epe,&row);
508:     {
509:       PetscInt nrows = 0;
510:       for (PetscInt c=0; c<dof[0]; ++c) {
511:         row[nrows].c = c;
512:         row[nrows].loc = DMSTAG_LEFT;
513:         ++nrows;
514:       }
515:       for (PetscInt c=0; c<dof[1]; ++c) {
516:         row[nrows].c = c;
517:         row[nrows].loc = DMSTAG_ELEMENT;
518:         ++nrows;
519:       }
520:     }
521:     PetscMalloc1(epe,&col);
522:     {
523:       PetscInt ncols = 0;
524:       for (PetscInt c=0; c<dof[0]; ++c) {
525:         col[ncols].c = c;
526:         col[ncols].loc = DMSTAG_LEFT;
527:         ++ncols;
528:       }
529:       for (PetscInt c=0; c<dof[1]; ++c) {
530:         col[ncols].c = c;
531:         col[ncols].loc = DMSTAG_ELEMENT;
532:         ++ncols;
533:       }
534:     }
535:     for (PetscInt e=start; e<start+n+n_extra; ++e) {
536:       for (PetscInt i=0; i<epe; ++i) {
537:         row[i].i = e;
538:       }
539:       for (PetscInt offset = -stencil_width; offset<=stencil_width; ++offset) {
540:         const PetscInt e_offset = e + offset;

542:         /* Only set values corresponding to elements which can have non-dummy entries,
543:            meaning those that map to unknowns in the global representation. In the periodic
544:            case, this is the entire stencil, but in all other cases, only includes a single
545:            "extra" element which is partially outside the physical domain (those points in the
546:            global representation */
547:         if (boundary_type_x == DM_BOUNDARY_PERIODIC || (e_offset < N+1 && e_offset >= 0)) {
548:           for (PetscInt i=0; i<epe; ++i) {
549:             col[i].i = e_offset;
550:           }
551:           DMStagMatSetValuesStencil(dm,A,epe,row,epe,col,NULL,INSERT_VALUES);
552:         }
553:       }
554:     }
555:     PetscFree(row);
556:     PetscFree(col);
557:   } else SETERRQ(PetscObjectComm((PetscObject)dm),PETSC_ERR_ARG_OUTOFRANGE,"Unsupported stencil type %s",DMStagStencilTypes[stencil_type]);
558:   MatAssemblyBegin(A,MAT_FINAL_ASSEMBLY);
559:   MatAssemblyEnd(A,MAT_FINAL_ASSEMBLY);
560:   return 0;
561: }