Actual source code: da2.c

petsc-3.9.4 2018-09-11
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  2:  #include <petsc/private/dmdaimpl.h>
  3:  #include <petscdraw.h>

  5: static PetscErrorCode DMView_DA_2d(DM da,PetscViewer viewer)
  6: {
  8:   PetscMPIInt    rank;
  9:   PetscBool      iascii,isdraw,isglvis,isbinary;
 10:   DM_DA          *dd = (DM_DA*)da->data;
 11: #if defined(PETSC_HAVE_MATLAB_ENGINE)
 12:   PetscBool ismatlab;
 13: #endif

 16:   MPI_Comm_rank(PetscObjectComm((PetscObject)da),&rank);

 18:   PetscObjectTypeCompare((PetscObject)viewer,PETSCVIEWERASCII,&iascii);
 19:   PetscObjectTypeCompare((PetscObject)viewer,PETSCVIEWERDRAW,&isdraw);
 20:   PetscObjectTypeCompare((PetscObject)viewer,PETSCVIEWERGLVIS,&isglvis);
 21:   PetscObjectTypeCompare((PetscObject)viewer,PETSCVIEWERBINARY,&isbinary);
 22: #if defined(PETSC_HAVE_MATLAB_ENGINE)
 23:   PetscObjectTypeCompare((PetscObject)viewer,PETSCVIEWERMATLAB,&ismatlab);
 24: #endif
 25:   if (iascii) {
 26:     PetscViewerFormat format;

 28:     PetscViewerGetFormat(viewer, &format);
 29:     if (format == PETSC_VIEWER_LOAD_BALANCE) {
 30:       PetscInt      i,nmax = 0,nmin = PETSC_MAX_INT,navg = 0,*nz,nzlocal;
 31:       DMDALocalInfo info;
 32:       PetscMPIInt   size;
 33:       MPI_Comm_size(PetscObjectComm((PetscObject)da),&size);
 34:       DMDAGetLocalInfo(da,&info);
 35:       nzlocal = info.xm*info.ym;
 36:       PetscMalloc1(size,&nz);
 37:       MPI_Allgather(&nzlocal,1,MPIU_INT,nz,1,MPIU_INT,PetscObjectComm((PetscObject)da));
 38:       for (i=0; i<(PetscInt)size; i++) {
 39:         nmax = PetscMax(nmax,nz[i]);
 40:         nmin = PetscMin(nmin,nz[i]);
 41:         navg += nz[i];
 42:       }
 43:       PetscFree(nz);
 44:       navg = navg/size;
 45:       PetscViewerASCIIPrintf(viewer,"  Load Balance - Grid Points: Min %D  avg %D  max %D\n",nmin,navg,nmax);
 46:       return(0);
 47:     }
 48:     if (format != PETSC_VIEWER_ASCII_VTK && format != PETSC_VIEWER_ASCII_VTK_CELL && format != PETSC_VIEWER_ASCII_GLVIS) {
 49:       DMDALocalInfo info;
 50:       DMDAGetLocalInfo(da,&info);
 51:       PetscViewerASCIIPushSynchronized(viewer);
 52:       PetscViewerASCIISynchronizedPrintf(viewer,"Processor [%d] M %D N %D m %D n %D w %D s %D\n",rank,dd->M,dd->N,dd->m,dd->n,dd->w,dd->s);
 53:       PetscViewerASCIISynchronizedPrintf(viewer,"X range of indices: %D %D, Y range of indices: %D %D\n",info.xs,info.xs+info.xm,info.ys,info.ys+info.ym);
 54:       PetscViewerFlush(viewer);
 55:       PetscViewerASCIIPopSynchronized(viewer);
 56:     } else if (format == PETSC_VIEWER_ASCII_GLVIS) {
 57:       DMView_DA_GLVis(da,viewer);
 58:     } else {
 59:       DMView_DA_VTK(da,viewer);
 60:     }
 61:   } else if (isdraw) {
 62:     PetscDraw      draw;
 63:     double         ymin = -1*dd->s-1,ymax = dd->N+dd->s;
 64:     double         xmin = -1*dd->s-1,xmax = dd->M+dd->s;
 65:     double         x,y;
 66:     PetscInt       base;
 67:     const PetscInt *idx;
 68:     char           node[10];
 69:     PetscBool      isnull;

 71:     PetscViewerDrawGetDraw(viewer,0,&draw);
 72:     PetscDrawIsNull(draw,&isnull);
 73:     if (isnull) return(0);

 75:     PetscDrawCheckResizedWindow(draw);
 76:     PetscDrawClear(draw);
 77:     PetscDrawSetCoordinates(draw,xmin,ymin,xmax,ymax);

 79:     PetscDrawCollectiveBegin(draw);
 80:     /* first processor draw all node lines */
 81:     if (!rank) {
 82:       ymin = 0.0; ymax = dd->N - 1;
 83:       for (xmin=0; xmin<dd->M; xmin++) {
 84:         PetscDrawLine(draw,xmin,ymin,xmin,ymax,PETSC_DRAW_BLACK);
 85:       }
 86:       xmin = 0.0; xmax = dd->M - 1;
 87:       for (ymin=0; ymin<dd->N; ymin++) {
 88:         PetscDrawLine(draw,xmin,ymin,xmax,ymin,PETSC_DRAW_BLACK);
 89:       }
 90:     }
 91:     PetscDrawCollectiveEnd(draw);
 92:     PetscDrawFlush(draw);
 93:     PetscDrawPause(draw);

 95:     PetscDrawCollectiveBegin(draw);
 96:     /* draw my box */
 97:     xmin = dd->xs/dd->w; xmax =(dd->xe-1)/dd->w; ymin = dd->ys; ymax = dd->ye - 1;
 98:     PetscDrawLine(draw,xmin,ymin,xmax,ymin,PETSC_DRAW_RED);
 99:     PetscDrawLine(draw,xmin,ymin,xmin,ymax,PETSC_DRAW_RED);
100:     PetscDrawLine(draw,xmin,ymax,xmax,ymax,PETSC_DRAW_RED);
101:     PetscDrawLine(draw,xmax,ymin,xmax,ymax,PETSC_DRAW_RED);
102:     /* put in numbers */
103:     base = (dd->base)/dd->w;
104:     for (y=ymin; y<=ymax; y++) {
105:       for (x=xmin; x<=xmax; x++) {
106:         PetscSNPrintf(node,sizeof(node),"%d",(int)base++);
107:         PetscDrawString(draw,x,y,PETSC_DRAW_BLACK,node);
108:       }
109:     }
110:     PetscDrawCollectiveEnd(draw);
111:     PetscDrawFlush(draw);
112:     PetscDrawPause(draw);

114:     PetscDrawCollectiveBegin(draw);
115:     /* overlay ghost numbers, useful for error checking */
116:     ISLocalToGlobalMappingGetBlockIndices(da->ltogmap,&idx);
117:     base = 0; xmin = dd->Xs; xmax = dd->Xe; ymin = dd->Ys; ymax = dd->Ye;
118:     for (y=ymin; y<ymax; y++) {
119:       for (x=xmin; x<xmax; x++) {
120:         if ((base % dd->w) == 0) {
121:           PetscSNPrintf(node,sizeof(node),"%d",(int)(idx[base/dd->w]));
122:           PetscDrawString(draw,x/dd->w,y,PETSC_DRAW_BLUE,node);
123:         }
124:         base++;
125:       }
126:     }
127:     ISLocalToGlobalMappingRestoreBlockIndices(da->ltogmap,&idx);
128:     PetscDrawCollectiveEnd(draw);
129:     PetscDrawFlush(draw);
130:     PetscDrawPause(draw);
131:     PetscDrawSave(draw);
132:   } else if (isglvis) {
133:     DMView_DA_GLVis(da,viewer);
134:   } else if (isbinary) {
135:     DMView_DA_Binary(da,viewer);
136: #if defined(PETSC_HAVE_MATLAB_ENGINE)
137:   } else if (ismatlab) {
138:     DMView_DA_Matlab(da,viewer);
139: #endif
140:   }
141:   return(0);
142: }

144: /*
145:       M is number of grid points
146:       m is number of processors

148: */
149: PetscErrorCode  DMDASplitComm2d(MPI_Comm comm,PetscInt M,PetscInt N,PetscInt sw,MPI_Comm *outcomm)
150: {
152:   PetscInt       m,n = 0,x = 0,y = 0;
153:   PetscMPIInt    size,csize,rank;

156:   MPI_Comm_size(comm,&size);
157:   MPI_Comm_rank(comm,&rank);

159:   csize = 4*size;
160:   do {
161:     if (csize % 4) SETERRQ4(PETSC_COMM_SELF,PETSC_ERR_ARG_INCOMP,"Cannot split communicator of size %d tried %d %D %D",size,csize,x,y);
162:     csize = csize/4;

164:     m = (PetscInt)(0.5 + PetscSqrtReal(((PetscReal)M)*((PetscReal)csize)/((PetscReal)N)));
165:     if (!m) m = 1;
166:     while (m > 0) {
167:       n = csize/m;
168:       if (m*n == csize) break;
169:       m--;
170:     }
171:     if (M > N && m < n) {PetscInt _m = m; m = n; n = _m;}

173:     x = M/m + ((M % m) > ((csize-1) % m));
174:     y = (N + (csize-1)/m)/n;
175:   } while ((x < 4 || y < 4) && csize > 1);
176:   if (size != csize) {
177:     MPI_Group   entire_group,sub_group;
178:     PetscMPIInt i,*groupies;

180:     MPI_Comm_group(comm,&entire_group);
181:     PetscMalloc1(csize,&groupies);
182:     for (i=0; i<csize; i++) {
183:       groupies[i] = (rank/csize)*csize + i;
184:     }
185:     MPI_Group_incl(entire_group,csize,groupies,&sub_group);
186:     PetscFree(groupies);
187:     MPI_Comm_create(comm,sub_group,outcomm);
188:     MPI_Group_free(&entire_group);
189:     MPI_Group_free(&sub_group);
190:     PetscInfo1(0,"DMDASplitComm2d:Creating redundant coarse problems of size %d\n",csize);
191:   } else {
192:     *outcomm = comm;
193:   }
194:   return(0);
195: }

197: #if defined(new)
198: /*
199:   DMDAGetDiagonal_MFFD - Gets the diagonal for a matrix free matrix where local
200:     function lives on a DMDA

202:         y ~= (F(u + ha) - F(u))/h,
203:   where F = nonlinear function, as set by SNESSetFunction()
204:         u = current iterate
205:         h = difference interval
206: */
207: PetscErrorCode DMDAGetDiagonal_MFFD(DM da,Vec U,Vec a)
208: {
209:   PetscScalar    h,*aa,*ww,v;
210:   PetscReal      epsilon = PETSC_SQRT_MACHINE_EPSILON,umin = 100.0*PETSC_SQRT_MACHINE_EPSILON;
212:   PetscInt       gI,nI;
213:   MatStencil     stencil;
214:   DMDALocalInfo  info;

217:   (*ctx->func)(0,U,a,ctx->funcctx);
218:   (*ctx->funcisetbase)(U,ctx->funcctx);

220:   VecGetArray(U,&ww);
221:   VecGetArray(a,&aa);

223:   nI = 0;
224:   h  = ww[gI];
225:   if (h == 0.0) h = 1.0;
226:   if (PetscAbsScalar(h) < umin && PetscRealPart(h) >= 0.0) h = umin;
227:   else if (PetscRealPart(h) < 0.0 && PetscAbsScalar(h) < umin) h = -umin;
228:   h *= epsilon;

230:   ww[gI] += h;
231:   (*ctx->funci)(i,w,&v,ctx->funcctx);
232:   aa[nI]  = (v - aa[nI])/h;
233:   ww[gI] -= h;
234:   nI++;

236:   VecRestoreArray(U,&ww);
237:   VecRestoreArray(a,&aa);
238:   return(0);
239: }
240: #endif

242: PetscErrorCode  DMSetUp_DA_2D(DM da)
243: {
244:   DM_DA            *dd = (DM_DA*)da->data;
245:   const PetscInt   M            = dd->M;
246:   const PetscInt   N            = dd->N;
247:   PetscInt         m            = dd->m;
248:   PetscInt         n            = dd->n;
249:   const PetscInt   dof          = dd->w;
250:   const PetscInt   s            = dd->s;
251:   DMBoundaryType   bx           = dd->bx;
252:   DMBoundaryType   by           = dd->by;
253:   DMDAStencilType  stencil_type = dd->stencil_type;
254:   PetscInt         *lx          = dd->lx;
255:   PetscInt         *ly          = dd->ly;
256:   MPI_Comm         comm;
257:   PetscMPIInt      rank,size;
258:   PetscInt         xs,xe,ys,ye,x,y,Xs,Xe,Ys,Ye,IXs,IXe,IYs,IYe;
259:   PetscInt         up,down,left,right,i,n0,n1,n2,n3,n5,n6,n7,n8,*idx,nn;
260:   PetscInt         xbase,*bases,*ldims,j,x_t,y_t,s_t,base,count;
261:   PetscInt         s_x,s_y; /* s proportionalized to w */
262:   PetscInt         sn0 = 0,sn2 = 0,sn6 = 0,sn8 = 0;
263:   Vec              local,global;
264:   VecScatter       gtol;
265:   IS               to,from;
266:   PetscErrorCode   ierr;

269:   if (stencil_type == DMDA_STENCIL_BOX && (bx == DM_BOUNDARY_MIRROR || by == DM_BOUNDARY_MIRROR)) SETERRQ(PetscObjectComm((PetscObject)da),PETSC_ERR_SUP,"Mirror boundary and box stencil");
270:   PetscObjectGetComm((PetscObject)da,&comm);
271: #if !defined(PETSC_USE_64BIT_INDICES)
272:   if (((PetscInt64) M)*((PetscInt64) N)*((PetscInt64) dof) > (PetscInt64) PETSC_MPI_INT_MAX) SETERRQ3(comm,PETSC_ERR_INT_OVERFLOW,"Mesh of %D by %D by %D (dof) is too large for 32 bit indices",M,N,dof);
273: #endif

275:   if (dof < 1) SETERRQ1(comm,PETSC_ERR_ARG_OUTOFRANGE,"Must have 1 or more degrees of freedom per node: %D",dof);
276:   if (s < 0) SETERRQ1(comm,PETSC_ERR_ARG_OUTOFRANGE,"Stencil width cannot be negative: %D",s);

278:   MPI_Comm_size(comm,&size);
279:   MPI_Comm_rank(comm,&rank);

281:   dd->p = 1;
282:   if (m != PETSC_DECIDE) {
283:     if (m < 1) SETERRQ1(comm,PETSC_ERR_ARG_OUTOFRANGE,"Non-positive number of processors in X direction: %D",m);
284:     else if (m > size) SETERRQ2(comm,PETSC_ERR_ARG_OUTOFRANGE,"Too many processors in X direction: %D %d",m,size);
285:   }
286:   if (n != PETSC_DECIDE) {
287:     if (n < 1) SETERRQ1(comm,PETSC_ERR_ARG_OUTOFRANGE,"Non-positive number of processors in Y direction: %D",n);
288:     else if (n > size) SETERRQ2(comm,PETSC_ERR_ARG_OUTOFRANGE,"Too many processors in Y direction: %D %d",n,size);
289:   }

291:   if (m == PETSC_DECIDE || n == PETSC_DECIDE) {
292:     if (n != PETSC_DECIDE) {
293:       m = size/n;
294:     } else if (m != PETSC_DECIDE) {
295:       n = size/m;
296:     } else {
297:       /* try for squarish distribution */
298:       m = (PetscInt)(0.5 + PetscSqrtReal(((PetscReal)M)*((PetscReal)size)/((PetscReal)N)));
299:       if (!m) m = 1;
300:       while (m > 0) {
301:         n = size/m;
302:         if (m*n == size) break;
303:         m--;
304:       }
305:       if (M > N && m < n) {PetscInt _m = m; m = n; n = _m;}
306:     }
307:     if (m*n != size) SETERRQ(comm,PETSC_ERR_PLIB,"Unable to create partition, check the size of the communicator and input m and n ");
308:   } else if (m*n != size) SETERRQ(comm,PETSC_ERR_ARG_OUTOFRANGE,"Given Bad partition");

310:   if (M < m) SETERRQ2(comm,PETSC_ERR_ARG_OUTOFRANGE,"Partition in x direction is too fine! %D %D",M,m);
311:   if (N < n) SETERRQ2(comm,PETSC_ERR_ARG_OUTOFRANGE,"Partition in y direction is too fine! %D %D",N,n);

313:   /*
314:      Determine locally owned region
315:      xs is the first local node number, x is the number of local nodes
316:   */
317:   if (!lx) {
318:     PetscMalloc1(m, &dd->lx);
319:     lx   = dd->lx;
320:     for (i=0; i<m; i++) {
321:       lx[i] = M/m + ((M % m) > i);
322:     }
323:   }
324:   x  = lx[rank % m];
325:   xs = 0;
326:   for (i=0; i<(rank % m); i++) {
327:     xs += lx[i];
328:   }
329: #if defined(PETSC_USE_DEBUG)
330:   left = xs;
331:   for (i=(rank % m); i<m; i++) {
332:     left += lx[i];
333:   }
334:   if (left != M) SETERRQ2(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"Sum of lx across processors not equal to M: %D %D",left,M);
335: #endif

337:   /*
338:      Determine locally owned region
339:      ys is the first local node number, y is the number of local nodes
340:   */
341:   if (!ly) {
342:     PetscMalloc1(n, &dd->ly);
343:     ly   = dd->ly;
344:     for (i=0; i<n; i++) {
345:       ly[i] = N/n + ((N % n) > i);
346:     }
347:   }
348:   y  = ly[rank/m];
349:   ys = 0;
350:   for (i=0; i<(rank/m); i++) {
351:     ys += ly[i];
352:   }
353: #if defined(PETSC_USE_DEBUG)
354:   left = ys;
355:   for (i=(rank/m); i<n; i++) {
356:     left += ly[i];
357:   }
358:   if (left != N) SETERRQ2(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"Sum of ly across processors not equal to N: %D %D",left,N);
359: #endif

361:   /*
362:    check if the scatter requires more than one process neighbor or wraps around
363:    the domain more than once
364:   */
365:   if ((x < s) && ((m > 1) || (bx == DM_BOUNDARY_PERIODIC))) SETERRQ2(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"Local x-width of domain x %D is smaller than stencil width s %D",x,s);
366:   if ((y < s) && ((n > 1) || (by == DM_BOUNDARY_PERIODIC))) SETERRQ2(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"Local y-width of domain y %D is smaller than stencil width s %D",y,s);
367:   xe = xs + x;
368:   ye = ys + y;

370:   /* determine ghost region (Xs) and region scattered into (IXs)  */
371:   if (xs-s > 0) {
372:     Xs = xs - s; IXs = xs - s;
373:   } else {
374:     if (bx) {
375:       Xs = xs - s;
376:     } else {
377:       Xs = 0;
378:     }
379:     IXs = 0;
380:   }
381:   if (xe+s <= M) {
382:     Xe = xe + s; IXe = xe + s;
383:   } else {
384:     if (bx) {
385:       Xs = xs - s; Xe = xe + s;
386:     } else {
387:       Xe = M;
388:     }
389:     IXe = M;
390:   }

392:   if (bx == DM_BOUNDARY_PERIODIC || bx == DM_BOUNDARY_MIRROR) {
393:     IXs = xs - s;
394:     IXe = xe + s;
395:     Xs  = xs - s;
396:     Xe  = xe + s;
397:   }

399:   if (ys-s > 0) {
400:     Ys = ys - s; IYs = ys - s;
401:   } else {
402:     if (by) {
403:       Ys = ys - s;
404:     } else {
405:       Ys = 0;
406:     }
407:     IYs = 0;
408:   }
409:   if (ye+s <= N) {
410:     Ye = ye + s; IYe = ye + s;
411:   } else {
412:     if (by) {
413:       Ye = ye + s;
414:     } else {
415:       Ye = N;
416:     }
417:     IYe = N;
418:   }

420:   if (by == DM_BOUNDARY_PERIODIC || by == DM_BOUNDARY_MIRROR) {
421:     IYs = ys - s;
422:     IYe = ye + s;
423:     Ys  = ys - s;
424:     Ye  = ye + s;
425:   }

427:   /* stencil length in each direction */
428:   s_x = s;
429:   s_y = s;

431:   /* determine starting point of each processor */
432:   nn       = x*y;
433:   PetscMalloc2(size+1,&bases,size,&ldims);
434:   MPI_Allgather(&nn,1,MPIU_INT,ldims,1,MPIU_INT,comm);
435:   bases[0] = 0;
436:   for (i=1; i<=size; i++) {
437:     bases[i] = ldims[i-1];
438:   }
439:   for (i=1; i<=size; i++) {
440:     bases[i] += bases[i-1];
441:   }
442:   base = bases[rank]*dof;

444:   /* allocate the base parallel and sequential vectors */
445:   dd->Nlocal = x*y*dof;
446:   VecCreateMPIWithArray(comm,dof,dd->Nlocal,PETSC_DECIDE,NULL,&global);
447:   dd->nlocal = (Xe-Xs)*(Ye-Ys)*dof;
448:   VecCreateSeqWithArray(PETSC_COMM_SELF,dof,dd->nlocal,NULL,&local);

450:   /* generate global to local vector scatter and local to global mapping*/

452:   /* global to local must include ghost points within the domain,
453:      but not ghost points outside the domain that aren't periodic */
454:   PetscMalloc1((IXe-IXs)*(IYe-IYs),&idx);
455:   if (stencil_type == DMDA_STENCIL_BOX) {
456:     left  = IXs - Xs; right = left + (IXe-IXs);
457:     down  = IYs - Ys; up = down + (IYe-IYs);
458:     count = 0;
459:     for (i=down; i<up; i++) {
460:       for (j=left; j<right; j++) {
461:         idx[count++] = j + i*(Xe-Xs);
462:       }
463:     }
464:     ISCreateBlock(comm,dof,count,idx,PETSC_OWN_POINTER,&to);

466:   } else {
467:     /* must drop into cross shape region */
468:     /*       ---------|
469:             |  top    |
470:          |---         ---| up
471:          |   middle      |
472:          |               |
473:          ----         ---- down
474:             | bottom  |
475:             -----------
476:          Xs xs        xe Xe */
477:     left  = xs - Xs; right = left + x;
478:     down  = ys - Ys; up = down + y;
479:     count = 0;
480:     /* bottom */
481:     for (i=(IYs-Ys); i<down; i++) {
482:       for (j=left; j<right; j++) {
483:         idx[count++] = j + i*(Xe-Xs);
484:       }
485:     }
486:     /* middle */
487:     for (i=down; i<up; i++) {
488:       for (j=(IXs-Xs); j<(IXe-Xs); j++) {
489:         idx[count++] = j + i*(Xe-Xs);
490:       }
491:     }
492:     /* top */
493:     for (i=up; i<up+IYe-ye; i++) {
494:       for (j=left; j<right; j++) {
495:         idx[count++] = j + i*(Xe-Xs);
496:       }
497:     }
498:     ISCreateBlock(comm,dof,count,idx,PETSC_OWN_POINTER,&to);
499:   }


502:   /* determine who lies on each side of us stored in    n6 n7 n8
503:                                                         n3    n5
504:                                                         n0 n1 n2
505:   */

507:   /* Assume the Non-Periodic Case */
508:   n1 = rank - m;
509:   if (rank % m) {
510:     n0 = n1 - 1;
511:   } else {
512:     n0 = -1;
513:   }
514:   if ((rank+1) % m) {
515:     n2 = n1 + 1;
516:     n5 = rank + 1;
517:     n8 = rank + m + 1; if (n8 >= m*n) n8 = -1;
518:   } else {
519:     n2 = -1; n5 = -1; n8 = -1;
520:   }
521:   if (rank % m) {
522:     n3 = rank - 1;
523:     n6 = n3 + m; if (n6 >= m*n) n6 = -1;
524:   } else {
525:     n3 = -1; n6 = -1;
526:   }
527:   n7 = rank + m; if (n7 >= m*n) n7 = -1;

529:   if (bx == DM_BOUNDARY_PERIODIC && by == DM_BOUNDARY_PERIODIC) {
530:     /* Modify for Periodic Cases */
531:     /* Handle all four corners */
532:     if ((n6 < 0) && (n7 < 0) && (n3 < 0)) n6 = m-1;
533:     if ((n8 < 0) && (n7 < 0) && (n5 < 0)) n8 = 0;
534:     if ((n2 < 0) && (n5 < 0) && (n1 < 0)) n2 = size-m;
535:     if ((n0 < 0) && (n3 < 0) && (n1 < 0)) n0 = size-1;

537:     /* Handle Top and Bottom Sides */
538:     if (n1 < 0) n1 = rank + m * (n-1);
539:     if (n7 < 0) n7 = rank - m * (n-1);
540:     if ((n3 >= 0) && (n0 < 0)) n0 = size - m + rank - 1;
541:     if ((n3 >= 0) && (n6 < 0)) n6 = (rank%m)-1;
542:     if ((n5 >= 0) && (n2 < 0)) n2 = size - m + rank + 1;
543:     if ((n5 >= 0) && (n8 < 0)) n8 = (rank%m)+1;

545:     /* Handle Left and Right Sides */
546:     if (n3 < 0) n3 = rank + (m-1);
547:     if (n5 < 0) n5 = rank - (m-1);
548:     if ((n1 >= 0) && (n0 < 0)) n0 = rank-1;
549:     if ((n1 >= 0) && (n2 < 0)) n2 = rank-2*m+1;
550:     if ((n7 >= 0) && (n6 < 0)) n6 = rank+2*m-1;
551:     if ((n7 >= 0) && (n8 < 0)) n8 = rank+1;
552:   } else if (by == DM_BOUNDARY_PERIODIC) {  /* Handle Top and Bottom Sides */
553:     if (n1 < 0) n1 = rank + m * (n-1);
554:     if (n7 < 0) n7 = rank - m * (n-1);
555:     if ((n3 >= 0) && (n0 < 0)) n0 = size - m + rank - 1;
556:     if ((n3 >= 0) && (n6 < 0)) n6 = (rank%m)-1;
557:     if ((n5 >= 0) && (n2 < 0)) n2 = size - m + rank + 1;
558:     if ((n5 >= 0) && (n8 < 0)) n8 = (rank%m)+1;
559:   } else if (bx == DM_BOUNDARY_PERIODIC) { /* Handle Left and Right Sides */
560:     if (n3 < 0) n3 = rank + (m-1);
561:     if (n5 < 0) n5 = rank - (m-1);
562:     if ((n1 >= 0) && (n0 < 0)) n0 = rank-1;
563:     if ((n1 >= 0) && (n2 < 0)) n2 = rank-2*m+1;
564:     if ((n7 >= 0) && (n6 < 0)) n6 = rank+2*m-1;
565:     if ((n7 >= 0) && (n8 < 0)) n8 = rank+1;
566:   }

568:   PetscMalloc1(9,&dd->neighbors);

570:   dd->neighbors[0] = n0;
571:   dd->neighbors[1] = n1;
572:   dd->neighbors[2] = n2;
573:   dd->neighbors[3] = n3;
574:   dd->neighbors[4] = rank;
575:   dd->neighbors[5] = n5;
576:   dd->neighbors[6] = n6;
577:   dd->neighbors[7] = n7;
578:   dd->neighbors[8] = n8;

580:   if (stencil_type == DMDA_STENCIL_STAR) {
581:     /* save corner processor numbers */
582:     sn0 = n0; sn2 = n2; sn6 = n6; sn8 = n8;
583:     n0  = n2 = n6 = n8 = -1;
584:   }

586:   PetscMalloc1((Xe-Xs)*(Ye-Ys),&idx);

588:   nn = 0;
589:   xbase = bases[rank];
590:   for (i=1; i<=s_y; i++) {
591:     if (n0 >= 0) { /* left below */
592:       x_t = lx[n0 % m];
593:       y_t = ly[(n0/m)];
594:       s_t = bases[n0] + x_t*y_t - (s_y-i)*x_t - s_x;
595:       for (j=0; j<s_x; j++) idx[nn++] = s_t++;
596:     }

598:     if (n1 >= 0) { /* directly below */
599:       x_t = x;
600:       y_t = ly[(n1/m)];
601:       s_t = bases[n1] + x_t*y_t - (s_y+1-i)*x_t;
602:       for (j=0; j<x_t; j++) idx[nn++] = s_t++;
603:     } else if (by == DM_BOUNDARY_MIRROR) {
604:       for (j=0; j<x; j++) idx[nn++] = bases[rank] + x*(s_y - i + 1)  + j;
605:     }

607:     if (n2 >= 0) { /* right below */
608:       x_t = lx[n2 % m];
609:       y_t = ly[(n2/m)];
610:       s_t = bases[n2] + x_t*y_t - (s_y+1-i)*x_t;
611:       for (j=0; j<s_x; j++) idx[nn++] = s_t++;
612:     }
613:   }

615:   for (i=0; i<y; i++) {
616:     if (n3 >= 0) { /* directly left */
617:       x_t = lx[n3 % m];
618:       /* y_t = y; */
619:       s_t = bases[n3] + (i+1)*x_t - s_x;
620:       for (j=0; j<s_x; j++) idx[nn++] = s_t++;
621:     } else if (bx == DM_BOUNDARY_MIRROR) {
622:       for (j=0; j<s_x; j++) idx[nn++] = bases[rank] + x*i + s_x - j;
623:     }

625:     for (j=0; j<x; j++) idx[nn++] = xbase++; /* interior */

627:     if (n5 >= 0) { /* directly right */
628:       x_t = lx[n5 % m];
629:       /* y_t = y; */
630:       s_t = bases[n5] + (i)*x_t;
631:       for (j=0; j<s_x; j++) idx[nn++] = s_t++;
632:     } else if (bx == DM_BOUNDARY_MIRROR) {
633:       for (j=0; j<s_x; j++) idx[nn++] = bases[rank] + x*(i + 1) - 2 - j;
634:     }
635:   }

637:   for (i=1; i<=s_y; i++) {
638:     if (n6 >= 0) { /* left above */
639:       x_t = lx[n6 % m];
640:       /* y_t = ly[(n6/m)]; */
641:       s_t = bases[n6] + (i)*x_t - s_x;
642:       for (j=0; j<s_x; j++) idx[nn++] = s_t++;
643:     }

645:     if (n7 >= 0) { /* directly above */
646:       x_t = x;
647:       /* y_t = ly[(n7/m)]; */
648:       s_t = bases[n7] + (i-1)*x_t;
649:       for (j=0; j<x_t; j++) idx[nn++] = s_t++;
650:     } else if (by == DM_BOUNDARY_MIRROR) {
651:       for (j=0; j<x; j++) idx[nn++] = bases[rank] + x*(y - i - 1)  + j;
652:     }

654:     if (n8 >= 0) { /* right above */
655:       x_t = lx[n8 % m];
656:       /* y_t = ly[(n8/m)]; */
657:       s_t = bases[n8] + (i-1)*x_t;
658:       for (j=0; j<s_x; j++) idx[nn++] = s_t++;
659:     }
660:   }

662:   ISCreateBlock(comm,dof,nn,idx,PETSC_USE_POINTER,&from);
663:   VecScatterCreate(global,from,local,to,&gtol);
664:   PetscLogObjectParent((PetscObject)da,(PetscObject)gtol);
665:   ISDestroy(&to);
666:   ISDestroy(&from);

668:   if (stencil_type == DMDA_STENCIL_STAR) {
669:     n0 = sn0; n2 = sn2; n6 = sn6; n8 = sn8;
670:   }

672:   if (((stencil_type == DMDA_STENCIL_STAR)  || (bx && bx != DM_BOUNDARY_PERIODIC) || (by && by != DM_BOUNDARY_PERIODIC))) {
673:     /*
674:         Recompute the local to global mappings, this time keeping the
675:       information about the cross corner processor numbers and any ghosted
676:       but not periodic indices.
677:     */
678:     nn    = 0;
679:     xbase = bases[rank];
680:     for (i=1; i<=s_y; i++) {
681:       if (n0 >= 0) { /* left below */
682:         x_t = lx[n0 % m];
683:         y_t = ly[(n0/m)];
684:         s_t = bases[n0] + x_t*y_t - (s_y-i)*x_t - s_x;
685:         for (j=0; j<s_x; j++) idx[nn++] = s_t++;
686:       } else if (xs-Xs > 0 && ys-Ys > 0) {
687:         for (j=0; j<s_x; j++) idx[nn++] = -1;
688:       }
689:       if (n1 >= 0) { /* directly below */
690:         x_t = x;
691:         y_t = ly[(n1/m)];
692:         s_t = bases[n1] + x_t*y_t - (s_y+1-i)*x_t;
693:         for (j=0; j<x_t; j++) idx[nn++] = s_t++;
694:       } else if (ys-Ys > 0) {
695:         if (by == DM_BOUNDARY_MIRROR) {
696:           for (j=0; j<x; j++) idx[nn++] = bases[rank] + x*(s_y - i + 1)  + j;
697:         } else {
698:           for (j=0; j<x; j++) idx[nn++] = -1;
699:         }
700:       }
701:       if (n2 >= 0) { /* right below */
702:         x_t = lx[n2 % m];
703:         y_t = ly[(n2/m)];
704:         s_t = bases[n2] + x_t*y_t - (s_y+1-i)*x_t;
705:         for (j=0; j<s_x; j++) idx[nn++] = s_t++;
706:       } else if (Xe-xe> 0 && ys-Ys > 0) {
707:         for (j=0; j<s_x; j++) idx[nn++] = -1;
708:       }
709:     }

711:     for (i=0; i<y; i++) {
712:       if (n3 >= 0) { /* directly left */
713:         x_t = lx[n3 % m];
714:         /* y_t = y; */
715:         s_t = bases[n3] + (i+1)*x_t - s_x;
716:         for (j=0; j<s_x; j++) idx[nn++] = s_t++;
717:       } else if (xs-Xs > 0) {
718:         if (bx == DM_BOUNDARY_MIRROR) {
719:           for (j=0; j<s_x; j++) idx[nn++] = bases[rank] + x*i + s_x - j;
720:         } else {
721:           for (j=0; j<s_x; j++) idx[nn++] = -1;
722:         }
723:       }

725:       for (j=0; j<x; j++) idx[nn++] = xbase++; /* interior */

727:       if (n5 >= 0) { /* directly right */
728:         x_t = lx[n5 % m];
729:         /* y_t = y; */
730:         s_t = bases[n5] + (i)*x_t;
731:         for (j=0; j<s_x; j++) idx[nn++] = s_t++;
732:       } else if (Xe-xe > 0) {
733:         if (bx == DM_BOUNDARY_MIRROR) {
734:           for (j=0; j<s_x; j++) idx[nn++] = bases[rank] + x*(i + 1) - 2 - j;
735:         } else {
736:           for (j=0; j<s_x; j++) idx[nn++] = -1;
737:         }
738:       }
739:     }

741:     for (i=1; i<=s_y; i++) {
742:       if (n6 >= 0) { /* left above */
743:         x_t = lx[n6 % m];
744:         /* y_t = ly[(n6/m)]; */
745:         s_t = bases[n6] + (i)*x_t - s_x;
746:         for (j=0; j<s_x; j++) idx[nn++] = s_t++;
747:       } else if (xs-Xs > 0 && Ye-ye > 0) {
748:         for (j=0; j<s_x; j++) idx[nn++] = -1;
749:       }
750:       if (n7 >= 0) { /* directly above */
751:         x_t = x;
752:         /* y_t = ly[(n7/m)]; */
753:         s_t = bases[n7] + (i-1)*x_t;
754:         for (j=0; j<x_t; j++) idx[nn++] = s_t++;
755:       } else if (Ye-ye > 0) {
756:         if (by == DM_BOUNDARY_MIRROR) {
757:           for (j=0; j<x; j++) idx[nn++] = bases[rank] + x*(y - i - 1)  + j;
758:         } else {
759:           for (j=0; j<x; j++) idx[nn++] = -1;
760:         }
761:       }
762:       if (n8 >= 0) { /* right above */
763:         x_t = lx[n8 % m];
764:         /* y_t = ly[(n8/m)]; */
765:         s_t = bases[n8] + (i-1)*x_t;
766:         for (j=0; j<s_x; j++) idx[nn++] = s_t++;
767:       } else if (Xe-xe > 0 && Ye-ye > 0) {
768:         for (j=0; j<s_x; j++) idx[nn++] = -1;
769:       }
770:     }
771:   }
772:   /*
773:      Set the local to global ordering in the global vector, this allows use
774:      of VecSetValuesLocal().
775:   */
776:   ISLocalToGlobalMappingCreate(comm,dof,nn,idx,PETSC_OWN_POINTER,&da->ltogmap);
777:   PetscLogObjectParent((PetscObject)da,(PetscObject)da->ltogmap);

779:   PetscFree2(bases,ldims);
780:   dd->m = m;  dd->n  = n;
781:   /* note petsc expects xs/xe/Xs/Xe to be multiplied by #dofs in many places */
782:   dd->xs = xs*dof; dd->xe = xe*dof; dd->ys = ys; dd->ye = ye; dd->zs = 0; dd->ze = 1;
783:   dd->Xs = Xs*dof; dd->Xe = Xe*dof; dd->Ys = Ys; dd->Ye = Ye; dd->Zs = 0; dd->Ze = 1;

785:   VecDestroy(&local);
786:   VecDestroy(&global);

788:   dd->gtol      = gtol;
789:   dd->base      = base;
790:   da->ops->view = DMView_DA_2d;
791:   dd->ltol      = NULL;
792:   dd->ao        = NULL;
793:   return(0);
794: }

796: /*@C
797:    DMDACreate2d -  Creates an object that will manage the communication of  two-dimensional
798:    regular array data that is distributed across some processors.

800:    Collective on MPI_Comm

802:    Input Parameters:
803: +  comm - MPI communicator
804: .  bx,by - type of ghost nodes the array have.
805:          Use one of DM_BOUNDARY_NONE, DM_BOUNDARY_GHOSTED, DM_BOUNDARY_PERIODIC.
806: .  stencil_type - stencil type.  Use either DMDA_STENCIL_BOX or DMDA_STENCIL_STAR.
807: .  M,N - global dimension in each direction of the array
808: .  m,n - corresponding number of processors in each dimension
809:          (or PETSC_DECIDE to have calculated)
810: .  dof - number of degrees of freedom per node
811: .  s - stencil width
812: -  lx, ly - arrays containing the number of nodes in each cell along
813:            the x and y coordinates, or NULL. If non-null, these
814:            must be of length as m and n, and the corresponding
815:            m and n cannot be PETSC_DECIDE. The sum of the lx[] entries
816:            must be M, and the sum of the ly[] entries must be N.

818:    Output Parameter:
819: .  da - the resulting distributed array object

821:    Options Database Key:
822: +  -dm_view - Calls DMView() at the conclusion of DMDACreate2d()
823: .  -da_grid_x <nx> - number of grid points in x direction
824: .  -da_grid_y <ny> - number of grid points in y direction
825: .  -da_processors_x <nx> - number of processors in x direction
826: .  -da_processors_y <ny> - number of processors in y direction
827: .  -da_refine_x <rx> - refinement ratio in x direction
828: .  -da_refine_y <ry> - refinement ratio in y direction
829: -  -da_refine <n> - refine the DMDA n times before creating


832:    Level: beginner

834:    Notes:
835:    The stencil type DMDA_STENCIL_STAR with width 1 corresponds to the
836:    standard 5-pt stencil, while DMDA_STENCIL_BOX with width 1 denotes
837:    the standard 9-pt stencil.

839:    The array data itself is NOT stored in the DMDA, it is stored in Vec objects;
840:    The appropriate vector objects can be obtained with calls to DMCreateGlobalVector()
841:    and DMCreateLocalVector() and calls to VecDuplicate() if more are needed.

843:    You must call DMSetUp() after this call before using this DM.

845:    If you wish to use the options database to change values in the DMDA call DMSetFromOptions() after this call
846:    but before DMSetUp().

848: .keywords: distributed array, create, two-dimensional

850: .seealso: DMDestroy(), DMView(), DMDACreate1d(), DMDACreate3d(), DMGlobalToLocalBegin(), DMDAGetRefinementFactor(),
851:           DMGlobalToLocalEnd(), DMLocalToGlobalBegin(), DMLocalToLocalBegin(), DMLocalToLocalEnd(), DMDASetRefinementFactor(),
852:           DMDAGetInfo(), DMCreateGlobalVector(), DMCreateLocalVector(), DMDACreateNaturalVector(), DMLoad(), DMDAGetOwnershipRanges()

854: @*/

856: PetscErrorCode  DMDACreate2d(MPI_Comm comm,DMBoundaryType bx,DMBoundaryType by,DMDAStencilType stencil_type,
857:                           PetscInt M,PetscInt N,PetscInt m,PetscInt n,PetscInt dof,PetscInt s,const PetscInt lx[],const PetscInt ly[],DM *da)
858: {

862:   DMDACreate(comm, da);
863:   DMSetDimension(*da, 2);
864:   DMDASetSizes(*da, M, N, 1);
865:   DMDASetNumProcs(*da, m, n, PETSC_DECIDE);
866:   DMDASetBoundaryType(*da, bx, by, DM_BOUNDARY_NONE);
867:   DMDASetDof(*da, dof);
868:   DMDASetStencilType(*da, stencil_type);
869:   DMDASetStencilWidth(*da, s);
870:   DMDASetOwnershipRanges(*da, lx, ly, NULL);
871:   return(0);
872: }