Actual source code: stag1d.c

petsc-master 2020-07-05
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  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 faces, edges, 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/point/node/0-cell
 16: . dof1 - number of degrees of freedom per element/edge/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: {
 42:   PetscMPIInt    size;

 45:   MPI_Comm_size(comm,&size);
 46:   DMCreate(comm,dm);
 47:   DMSetDimension(*dm,1);
 48:   DMStagInitialize(bndx,DM_BOUNDARY_NONE,DM_BOUNDARY_NONE,M,0,0,size,0,0,dof0,dof1,0,0,stencilType,stencilWidth,lx,NULL,NULL,*dm);
 49:   return(0);
 50: }

 52: PETSC_INTERN PetscErrorCode DMStagSetUniformCoordinatesExplicit_1d(DM dm,PetscReal xmin,PetscReal xmax)
 53: {
 55:   DM_Stag        *stagCoord;
 56:   DM             dmCoord;
 57:   Vec            coordLocal,coord;
 58:   PetscReal      h,min;
 59:   PetscScalar    **arr;
 60:   PetscInt       ind,start,n,nExtra,s;
 61:   PetscInt       ileft,ielement;

 64:   DMGetCoordinateDM(dm, &dmCoord);
 65:   stagCoord = (DM_Stag*) dmCoord->data;
 66:   for (s=0; s<2; ++s) {
 67:     if (stagCoord->dof[s] !=0 && stagCoord->dof[s] != 1) SETERRQ2(PetscObjectComm((PetscObject)dm),PETSC_ERR_PLIB,"Coordinate DM in 1 dimensions must have 0 or 1 dof on each stratum, but stratum %d has %d dof",s,stagCoord->dof[s]);
 68:   }
 69:   DMGetLocalVector(dmCoord,&coordLocal);

 71:   DMStagVecGetArray(dmCoord,coordLocal,&arr);
 72:   if (stagCoord->dof[0]) {
 73:     DMStagGetLocationSlot(dmCoord,DMSTAG_LEFT,0,&ileft);
 74:   }
 75:   if (stagCoord->dof[1]) {
 76:     DMStagGetLocationSlot(dmCoord,DMSTAG_ELEMENT,0,&ielement);
 77:   }
 78:   DMStagGetCorners(dmCoord,&start,NULL,NULL,&n,NULL,NULL,&nExtra,NULL,NULL);

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

 83:   for(ind=start; ind<start + n + nExtra; ++ind) {
 84:     if (stagCoord->dof[0]) {
 85:       const PetscReal off = 0.0;
 86:         arr[ind][ileft] = min + ((PetscReal)ind + off) * h;
 87:     }
 88:     if (stagCoord->dof[1]) {
 89:       const PetscReal off = 0.5;
 90:         arr[ind][ielement] = min + ((PetscReal)ind + off) * h;
 91:     }
 92:   }
 93:   DMStagVecRestoreArray(dmCoord,coordLocal,&arr);
 94:   DMCreateGlobalVector(dmCoord,&coord);
 95:   DMLocalToGlobalBegin(dmCoord,coordLocal,INSERT_VALUES,coord);
 96:   DMLocalToGlobalEnd(dmCoord,coordLocal,INSERT_VALUES,coord);
 97:   DMSetCoordinates(dm,coord);
 98:   PetscLogObjectParent((PetscObject)dm,(PetscObject)coord);
 99:   VecDestroy(&coord);
100:   DMRestoreLocalVector(dmCoord,&coordLocal);
101:   return(0);
102: }

104: /* Helper functions used in DMSetUp_Stag() */
105: static PetscErrorCode DMStagComputeLocationOffsets_1d(DM);

107: PETSC_INTERN PetscErrorCode DMSetUp_Stag_1d(DM dm)
108: {
109:   PetscErrorCode  ierr;
110:   DM_Stag * const stag = (DM_Stag*)dm->data;
111:   PetscMPIInt     size,rank;
112:   MPI_Comm        comm;
113:   PetscInt        j;

116:   PetscObjectGetComm((PetscObject)dm,&comm);
117:   MPI_Comm_size(comm,&size);
118:   MPI_Comm_rank(comm,&rank);

120:   /* Check Global size */
121:   if (stag->N[0] < 1) SETERRQ1(comm,PETSC_ERR_ARG_OUTOFRANGE,"Global grid size of %D < 1 specified",stag->N[0]);

123:   /* Local sizes */
124:   if (stag->N[0] < size) SETERRQ2(comm,PETSC_ERR_ARG_OUTOFRANGE,"More ranks (%d) than elements (%D) specified",size,stag->N[0]);
125:   if (!stag->l[0]) {
126:     /* Divide equally, giving an extra elements to higher ranks */
127:     PetscMalloc1(stag->nRanks[0],&stag->l[0]);
128:     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);
129:   }
130:   {
131:     PetscInt Nchk = 0;
132:     for (j=0; j<size; ++j) Nchk += stag->l[0][j];
133:     if (Nchk != stag->N[0]) SETERRQ2(comm,PETSC_ERR_ARG_OUTOFRANGE,"Sum of specified local sizes (%D) is not equal to global size (%D)",Nchk,stag->N[0]);
134:   }
135:   stag->n[0] = stag->l[0][rank];

137:   /* Rank (trivial in 1d) */
138:   stag->rank[0]      = rank;
139:   stag->firstRank[0] = (PetscBool)(rank == 0);
140:   stag->lastRank[0]  = (PetscBool)(rank == size-1);

142:   /* Local (unghosted) numbers of entries */
143:   stag->entriesPerElement = stag->dof[0] + stag->dof[1];
144:   switch (stag->boundaryType[0]) {
145:     case DM_BOUNDARY_NONE:
146:     case DM_BOUNDARY_GHOSTED:  stag->entries = stag->n[0] * stag->entriesPerElement + (stag->lastRank[0] ?  stag->dof[0] : 0); break;
147:     case DM_BOUNDARY_PERIODIC: stag->entries = stag->n[0] * stag->entriesPerElement;                                           break;
148:     default: SETERRQ1(PETSC_COMM_WORLD,PETSC_ERR_SUP,"Unsupported x boundary type %s",DMBoundaryTypes[stag->boundaryType[0]]);
149:   }

151:   /* Starting element */
152:   stag->start[0] = 0;
153:   for(j=0; j<stag->rank[0]; ++j) stag->start[0] += stag->l[0][j];

155:   /* Local/ghosted size and starting element */
156:   switch (stag->boundaryType[0]) {
157:     case DM_BOUNDARY_NONE :
158:       switch (stag->stencilType) {
159:         case DMSTAG_STENCIL_NONE : /* Only dummy cells on the right */
160:           stag->startGhost[0] = stag->start[0];
161:           stag->nGhost[0]     = stag->n[0] + (stag->lastRank[0] ? 1 : 0);
162:           break;
163:         case DMSTAG_STENCIL_STAR :
164:         case DMSTAG_STENCIL_BOX :
165:           stag->startGhost[0] = stag->firstRank[0] ? stag->start[0]: stag->start[0] - stag->stencilWidth;
166:           stag->nGhost[0] = stag->n[0];
167:           stag->nGhost[0] += stag->firstRank[0] ? 0 : stag->stencilWidth;
168:           stag->nGhost[0] += stag->lastRank[0]  ? 1 : stag->stencilWidth;
169:           break;
170:         default :
171:           SETERRQ1(PETSC_COMM_WORLD,PETSC_ERR_SUP,"Unrecognized ghost stencil type %d",stag->stencilType);
172:       }
173:       break;
174:     case DM_BOUNDARY_GHOSTED:
175:       switch (stag->stencilType) {
176:         case DMSTAG_STENCIL_NONE :
177:           stag->startGhost[0] = stag->start[0];
178:           stag->nGhost[0]     = stag->n[0] + (stag->lastRank[0] ? 1 : 0);
179:           break;
180:         case DMSTAG_STENCIL_STAR :
181:         case DMSTAG_STENCIL_BOX :
182:           stag->startGhost[0] = stag->start[0] - stag->stencilWidth; /* This value may be negative */
183:           stag->nGhost[0]     = stag->n[0] + 2*stag->stencilWidth + (stag->lastRank[0] && stag->stencilWidth == 0 ? 1 : 0);
184:           break;
185:         default :
186:           SETERRQ1(PETSC_COMM_WORLD,PETSC_ERR_SUP,"Unrecognized ghost stencil type %d",stag->stencilType);
187:       }
188:       break;
189:     case DM_BOUNDARY_PERIODIC:
190:       switch (stag->stencilType) {
191:         case DMSTAG_STENCIL_NONE :
192:           stag->startGhost[0] = stag->start[0];
193:           stag->nGhost[0]     = stag->n[0];
194:           break;
195:         case DMSTAG_STENCIL_STAR :
196:         case DMSTAG_STENCIL_BOX :
197:           stag->startGhost[0] = stag->start[0] - stag->stencilWidth; /* This value may be negative */
198:           stag->nGhost[0]     = stag->n[0] + 2*stag->stencilWidth;
199:           break;
200:         default :
201:           SETERRQ1(PETSC_COMM_WORLD,PETSC_ERR_SUP,"Unrecognized ghost stencil type %d",stag->stencilType);
202:       }
203:       break;
204:     default :
205:       SETERRQ1(PETSC_COMM_WORLD,PETSC_ERR_SUP,"Unsupported x boundary type %s",DMBoundaryTypes[stag->boundaryType[0]]);
206:   }

208:   /* Total size of ghosted/local represention */
209:   stag->entriesGhost = stag->nGhost[0]*stag->entriesPerElement;

211:   /* Define neighbors */
212:   PetscMalloc1(3,&stag->neighbors);
213:   if (stag->firstRank[0]) {
214:     switch (stag->boundaryType[0]) {
215:       case DM_BOUNDARY_GHOSTED:
216:       case DM_BOUNDARY_NONE:     stag->neighbors[0] = -1;                break;
217:       case DM_BOUNDARY_PERIODIC: stag->neighbors[0] = stag->nRanks[0]-1; break;
218:       default : SETERRQ1(PETSC_COMM_WORLD,PETSC_ERR_SUP,"Unsupported x boundary type %s",DMBoundaryTypes[stag->boundaryType[0]]);
219:     }
220:   } else {
221:     stag->neighbors[0] = stag->rank[0]-1;
222:   }
223:   stag->neighbors[1] = stag->rank[0];
224:   if (stag->lastRank[0]) {
225:     switch (stag->boundaryType[0]) {
226:       case DM_BOUNDARY_GHOSTED:
227:       case DM_BOUNDARY_NONE:     stag->neighbors[2] = -1;                break;
228:       case DM_BOUNDARY_PERIODIC: stag->neighbors[2] = 0;                 break;
229:       default : SETERRQ1(PETSC_COMM_WORLD,PETSC_ERR_SUP,"Unsupported x boundary type %s",DMBoundaryTypes[stag->boundaryType[0]]);
230:     }
231:   } else {
232:     stag->neighbors[2] = stag->rank[0]+1;
233:   }

235:   if (stag->n[0] < stag->stencilWidth) {
236:     SETERRQ2(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);
237:   }

239:   /* Create global->local VecScatter and ISLocalToGlobalMapping */
240:   {
241:     PetscInt *idxLocal,*idxGlobal,*idxGlobalAll;
242:     PetscInt i,iLocal,d,entriesToTransferTotal,ghostOffsetStart,ghostOffsetEnd,nNonDummyGhost;
243:     IS       isLocal,isGlobal;

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

252:     /* Compute the number of non-dummy entries in the local representation
253:        This is equal to the number of non-dummy elements in the local (ghosted) representation,
254:        plus some extra entries on the right boundary on the last rank*/
255:     switch (stag->boundaryType[0]) {
256:       case DM_BOUNDARY_GHOSTED:
257:       case DM_BOUNDARY_NONE:
258:         entriesToTransferTotal = nNonDummyGhost * stag->entriesPerElement + (stag->lastRank[0] ? stag->dof[0] : 0);
259:         break;
260:       case DM_BOUNDARY_PERIODIC:
261:         entriesToTransferTotal = stag->entriesGhost; /* No dummy points */
262:         break;
263:       default :
264:         SETERRQ1(PETSC_COMM_WORLD,PETSC_ERR_SUP,"Unsupported x boundary type %s",DMBoundaryTypes[stag->boundaryType[0]]);
265:     }

267:     PetscMalloc1(entriesToTransferTotal,&idxLocal);
268:     PetscMalloc1(entriesToTransferTotal,&idxGlobal);
269:     PetscMalloc1(stag->entriesGhost,&idxGlobalAll);
270:     if (stag->boundaryType[0] == DM_BOUNDARY_NONE) {
271:       PetscInt count = 0,countAll = 0;
272:       /* Left ghost points and native points */
273:       for (i=stag->startGhost[0], iLocal=0; iLocal<nNonDummyGhost; ++i,++iLocal) {
274:         for (d=0; d<stag->entriesPerElement; ++d,++count,++countAll) {
275:           idxLocal [count]       = iLocal * stag->entriesPerElement + d;
276:           idxGlobal[count]       = i      * stag->entriesPerElement + d;
277:           idxGlobalAll[countAll] = i      * stag->entriesPerElement + d;
278:         }
279:       }
280:       /* Ghost points on the right
281:          Special case for last (partial dummy) element on the last rank */
282:       if (stag->lastRank[0] ) {
283:         i      = stag->N[0];
284:         iLocal = (stag->nGhost[0]-ghostOffsetEnd);
285:         /* Only vertex (0-cell) dofs in global representation */
286:         for (d=0; d<stag->dof[0]; ++d,++count,++countAll) {
287:           idxGlobal[count]       = i      * stag->entriesPerElement + d;
288:           idxLocal [count]       = iLocal * stag->entriesPerElement + d;
289:           idxGlobalAll[countAll] = i      * stag->entriesPerElement + d;
290:         }
291:         for (d=stag->dof[0]; d<stag->entriesPerElement; ++d,++countAll) { /* Additional dummy entries */
292:           idxGlobalAll[countAll] = -1;
293:         }
294:       }
295:     } else if (stag->boundaryType[0] == DM_BOUNDARY_PERIODIC) {
296:       PetscInt count = 0,iLocal = 0; /* No dummy points, so idxGlobal and idxGlobalAll are identical */
297:       const PetscInt iMin = stag->firstRank[0] ? stag->start[0] : stag->startGhost[0];
298:       const PetscInt iMax = stag->lastRank[0] ? stag->startGhost[0] + stag->nGhost[0] - stag->stencilWidth : stag->startGhost[0] + stag->nGhost[0];
299:       /* Ghost points on the left */
300:       if (stag->firstRank[0]) {
301:         for (i=stag->N[0]-stag->stencilWidth; iLocal<stag->stencilWidth; ++i,++iLocal) {
302:           for (d=0; d<stag->entriesPerElement; ++d,++count) {
303:             idxGlobal[count] = i      * stag->entriesPerElement + d;
304:             idxLocal [count] = iLocal * stag->entriesPerElement + d;
305:             idxGlobalAll[count] = idxGlobal[count];
306:           }
307:         }
308:       }
309:       /* Native points */
310:       for (i=iMin; i<iMax; ++i,++iLocal) {
311:         for (d=0; d<stag->entriesPerElement; ++d,++count) {
312:           idxGlobal[count] = i      * stag->entriesPerElement + d;
313:           idxLocal [count] = iLocal * stag->entriesPerElement + d;
314:           idxGlobalAll[count] = idxGlobal[count];
315:         }
316:       }
317:       /* Ghost points on the right */
318:       if (stag->lastRank[0]) {
319:         for (i=0; iLocal<stag->nGhost[0]; ++i,++iLocal) {
320:           for (d=0; d<stag->entriesPerElement; ++d,++count) {
321:             idxGlobal[count] = i      * stag->entriesPerElement + d;
322:             idxLocal [count] = iLocal * stag->entriesPerElement + d;
323:             idxGlobalAll[count] = idxGlobal[count];
324:           }
325:         }
326:       }
327:     } else if (stag->boundaryType[0] == DM_BOUNDARY_GHOSTED) {
328:       PetscInt count = 0,countAll = 0;
329:       /* Dummy elements on the left, on the first rank */
330:       if (stag->firstRank[0]) {
331:         for(iLocal=0; iLocal<ghostOffsetStart; ++iLocal) {
332:           /* Complete elements full of dummy entries */
333:           for (d=0; d<stag->entriesPerElement; ++d,++countAll) {
334:             idxGlobalAll[countAll] = -1;
335:           }
336:         }
337:         i = 0; /* nonDummy entries start with global entry 0 */
338:       } else {
339:         /* nonDummy entries start as usual */
340:         i = stag->startGhost[0];
341:         iLocal = 0;
342:       }

344:       /* non-Dummy entries */
345:       {
346:         PetscInt iLocalNonDummyMax = stag->firstRank[0] ? nNonDummyGhost + ghostOffsetStart : nNonDummyGhost;
347:         for (; iLocal<iLocalNonDummyMax; ++i,++iLocal) {
348:           for (d=0; d<stag->entriesPerElement; ++d,++count,++countAll) {
349:             idxLocal [count]       = iLocal * stag->entriesPerElement + d;
350:             idxGlobal[count]       = i      * stag->entriesPerElement + d;
351:             idxGlobalAll[countAll] = i      * stag->entriesPerElement + d;
352:           }
353:         }
354:       }

356:       /* (partial) dummy elements on the right, on the last rank */
357:       if (stag->lastRank[0]) {
358:         /* First one is partial dummy */
359:         i      = stag->N[0];
360:         iLocal = (stag->nGhost[0]-ghostOffsetEnd);
361:         for (d=0; d<stag->dof[0]; ++d,++count,++countAll) { /* Only vertex (0-cell) dofs in global representation */
362:           idxLocal [count]       = iLocal * stag->entriesPerElement + d;
363:           idxGlobal[count]       = i      * stag->entriesPerElement + d;
364:           idxGlobalAll[countAll] = i      * stag->entriesPerElement + d;
365:         }
366:         for (d=stag->dof[0]; d<stag->entriesPerElement; ++d,++countAll) { /* Additional dummy entries */
367:           idxGlobalAll[countAll] = -1;
368:         }
369:         for (iLocal = stag->nGhost[0] - ghostOffsetEnd + 1; iLocal < stag->nGhost[0]; ++iLocal) {
370:           /* Additional dummy elements */
371:           for (d=0; d<stag->entriesPerElement; ++d,++countAll) {
372:             idxGlobalAll[countAll] = -1;
373:           }
374:         }
375:       }
376:     } else SETERRQ1(PETSC_COMM_WORLD,PETSC_ERR_SUP,"Unsupported x boundary type %s",DMBoundaryTypes[stag->boundaryType[0]]);

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

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

384:     /* Create stag->gtol, which doesn't include dummy entries */
385:     {
386:       Vec local,global;
387:       VecCreateMPIWithArray(PetscObjectComm((PetscObject)dm),1,stag->entries,PETSC_DECIDE,NULL,&global);
388:       VecCreateSeqWithArray(PETSC_COMM_SELF,stag->entriesPerElement,stag->entriesGhost,NULL,&local);
389:       VecScatterCreate(global,isGlobal,local,isLocal,&stag->gtol);
390:       VecDestroy(&global);
391:       VecDestroy(&local);
392:     }

394:     /* In special cases, create a dedicated injective local-to-global map */
395:     if (stag->boundaryType[0] == DM_BOUNDARY_PERIODIC && stag->nRanks[0] == 1) {
396:       DMStagPopulateLocalToGlobalInjective(dm);
397:     }

399:     /* Destroy ISs */
400:     ISDestroy(&isLocal);
401:     ISDestroy(&isGlobal);

403:     /* Create local-to-global map (transferring pointer ownership) */
404:     ISLocalToGlobalMappingCreate(comm,1,stag->entriesGhost,idxGlobalAll,PETSC_OWN_POINTER,&dm->ltogmap);
405:     PetscLogObjectParent((PetscObject)dm,(PetscObject)dm->ltogmap);
406:   }

408:   /* Precompute location offsets */
409:   DMStagComputeLocationOffsets_1d(dm);

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

414:  return(0);
415: }

417: static PetscErrorCode DMStagComputeLocationOffsets_1d(DM dm)
418: {
419:   PetscErrorCode  ierr;
420:   DM_Stag * const stag = (DM_Stag*)dm->data;
421:   const PetscInt  epe = stag->entriesPerElement;

424:   PetscMalloc1(DMSTAG_NUMBER_LOCATIONS,&stag->locationOffsets);
425:   stag->locationOffsets[DMSTAG_LEFT]    = 0;
426:   stag->locationOffsets[DMSTAG_ELEMENT] = stag->locationOffsets[DMSTAG_LEFT] + stag->dof[0];
427:   stag->locationOffsets[DMSTAG_RIGHT]   = stag->locationOffsets[DMSTAG_LEFT] + epe;
428:   return(0);
429: }

431: PETSC_INTERN PetscErrorCode DMStagPopulateLocalToGlobalInjective_1d(DM dm)
432: {
433:   PetscErrorCode  ierr;
434:   DM_Stag * const stag = (DM_Stag*)dm->data;
435:   PetscInt        *idxLocal,*idxGlobal;
436:   PetscInt        i,iLocal,d,count;
437:   IS              isLocal,isGlobal;

440:   PetscMalloc1(stag->entries,&idxLocal);
441:   PetscMalloc1(stag->entries,&idxGlobal);
442:   count = 0;
443:   iLocal = stag->start[0]-stag->startGhost[0];
444:   for (i=stag->start[0]; i<stag->start[0]+stag->n[0]; ++i,++iLocal) {
445:     for (d=0; d<stag->entriesPerElement; ++d,++count) {
446:       idxGlobal[count] = i      * stag->entriesPerElement + d;
447:       idxLocal [count] = iLocal * stag->entriesPerElement + d;
448:     }
449:   }
450:   if (stag->lastRank[0] && stag->boundaryType[0] != DM_BOUNDARY_PERIODIC) {
451:     i = stag->start[0]+stag->n[0];
452:     iLocal = stag->start[0]-stag->startGhost[0] + stag->n[0];
453:     for (d=0; d<stag->dof[0]; ++d,++count) {
454:       idxGlobal[count] = i      * stag->entriesPerElement + d;
455:       idxLocal [count] = iLocal * stag->entriesPerElement + d;
456:     }
457:   }
458:   ISCreateGeneral(PetscObjectComm((PetscObject)dm),stag->entries,idxLocal,PETSC_OWN_POINTER,&isLocal);
459:   ISCreateGeneral(PetscObjectComm((PetscObject)dm),stag->entries,idxGlobal,PETSC_OWN_POINTER,&isGlobal);
460:   {
461:     Vec local,global;
462:     VecCreateMPIWithArray(PetscObjectComm((PetscObject)dm),1,stag->entries,PETSC_DECIDE,NULL,&global);
463:     VecCreateSeqWithArray(PETSC_COMM_SELF,stag->entriesPerElement,stag->entriesGhost,NULL,&local);
464:     VecScatterCreate(local,isLocal,global,isGlobal,&stag->ltog_injective);
465:     VecDestroy(&global);
466:     VecDestroy(&local);
467:   }
468:   ISDestroy(&isLocal);
469:   ISDestroy(&isGlobal);
470:   return(0);
471: }