xref: /petsc/src/dm/impls/da/dacreate.c (revision 1b37a2a7cc4a4fb30c3e967db1c694c0a1013f51)
1 #include <petsc/private/dmdaimpl.h> /*I   "petscdmda.h"   I*/
2 
3 static PetscErrorCode DMSetFromOptions_DA(DM da, PetscOptionItems *PetscOptionsObject)
4 {
5   DM_DA    *dd     = (DM_DA *)da->data;
6   PetscInt  refine = 0, dim = da->dim, maxnlevels = 100, refx[100], refy[100], refz[100], n, i;
7   PetscBool flg;
8 
9   PetscFunctionBegin;
10   PetscCheck(dd->M >= 0, PetscObjectComm((PetscObject)da), PETSC_ERR_ARG_OUTOFRANGE, "Dimension must be non-negative, call DMSetFromOptions() if you want to change the value at runtime");
11   PetscCheck(dd->N >= 0, PetscObjectComm((PetscObject)da), PETSC_ERR_ARG_OUTOFRANGE, "Dimension must be non-negative, call DMSetFromOptions() if you want to change the value at runtime");
12   PetscCheck(dd->P >= 0, PetscObjectComm((PetscObject)da), PETSC_ERR_ARG_OUTOFRANGE, "Dimension must be non-negative, call DMSetFromOptions() if you want to change the value at runtime");
13 
14   PetscOptionsHeadBegin(PetscOptionsObject, "DMDA Options");
15   PetscCall(PetscOptionsBoundedInt("-da_grid_x", "Number of grid points in x direction", "DMDASetSizes", dd->M, &dd->M, NULL, 1));
16   if (dim > 1) PetscCall(PetscOptionsBoundedInt("-da_grid_y", "Number of grid points in y direction", "DMDASetSizes", dd->N, &dd->N, NULL, 1));
17   if (dim > 2) PetscCall(PetscOptionsBoundedInt("-da_grid_z", "Number of grid points in z direction", "DMDASetSizes", dd->P, &dd->P, NULL, 1));
18 
19   PetscCall(PetscOptionsBoundedInt("-da_overlap", "Decomposition overlap in all directions", "DMDASetOverlap", dd->xol, &dd->xol, &flg, 0));
20   if (flg) PetscCall(DMDASetOverlap(da, dd->xol, dd->xol, dd->xol));
21   PetscCall(PetscOptionsBoundedInt("-da_overlap_x", "Decomposition overlap in x direction", "DMDASetOverlap", dd->xol, &dd->xol, NULL, 0));
22   if (dim > 1) PetscCall(PetscOptionsBoundedInt("-da_overlap_y", "Decomposition overlap in y direction", "DMDASetOverlap", dd->yol, &dd->yol, NULL, 0));
23   if (dim > 2) PetscCall(PetscOptionsBoundedInt("-da_overlap_z", "Decomposition overlap in z direction", "DMDASetOverlap", dd->zol, &dd->zol, NULL, 0));
24 
25   PetscCall(PetscOptionsBoundedInt("-da_local_subdomains", "", "DMDASetNumLocalSubdomains", dd->Nsub, &dd->Nsub, &flg, PETSC_DECIDE));
26   if (flg) PetscCall(DMDASetNumLocalSubDomains(da, dd->Nsub));
27 
28   /* Handle DMDA parallel distribution */
29   PetscCall(PetscOptionsBoundedInt("-da_processors_x", "Number of processors in x direction", "DMDASetNumProcs", dd->m, &dd->m, NULL, PETSC_DECIDE));
30   if (dim > 1) PetscCall(PetscOptionsBoundedInt("-da_processors_y", "Number of processors in y direction", "DMDASetNumProcs", dd->n, &dd->n, NULL, PETSC_DECIDE));
31   if (dim > 2) PetscCall(PetscOptionsBoundedInt("-da_processors_z", "Number of processors in z direction", "DMDASetNumProcs", dd->p, &dd->p, NULL, PETSC_DECIDE));
32   /* Handle DMDA refinement */
33   PetscCall(PetscOptionsBoundedInt("-da_refine_x", "Refinement ratio in x direction", "DMDASetRefinementFactor", dd->refine_x, &dd->refine_x, NULL, 1));
34   if (dim > 1) PetscCall(PetscOptionsBoundedInt("-da_refine_y", "Refinement ratio in y direction", "DMDASetRefinementFactor", dd->refine_y, &dd->refine_y, NULL, 1));
35   if (dim > 2) PetscCall(PetscOptionsBoundedInt("-da_refine_z", "Refinement ratio in z direction", "DMDASetRefinementFactor", dd->refine_z, &dd->refine_z, NULL, 1));
36   dd->coarsen_x = dd->refine_x;
37   dd->coarsen_y = dd->refine_y;
38   dd->coarsen_z = dd->refine_z;
39 
40   /* Get refinement factors, defaults taken from the coarse DMDA */
41   PetscCall(DMDAGetRefinementFactor(da, &refx[0], &refy[0], &refz[0]));
42   for (i = 1; i < maxnlevels; i++) {
43     refx[i] = refx[0];
44     refy[i] = refy[0];
45     refz[i] = refz[0];
46   }
47   n = maxnlevels;
48   PetscCall(PetscOptionsIntArray("-da_refine_hierarchy_x", "Refinement factor for each level", "None", refx, &n, &flg));
49   if (flg) {
50     dd->refine_x        = refx[0];
51     dd->refine_x_hier_n = n;
52     PetscCall(PetscMalloc1(n, &dd->refine_x_hier));
53     PetscCall(PetscArraycpy(dd->refine_x_hier, refx, n));
54   }
55   if (dim > 1) {
56     n = maxnlevels;
57     PetscCall(PetscOptionsIntArray("-da_refine_hierarchy_y", "Refinement factor for each level", "None", refy, &n, &flg));
58     if (flg) {
59       dd->refine_y        = refy[0];
60       dd->refine_y_hier_n = n;
61       PetscCall(PetscMalloc1(n, &dd->refine_y_hier));
62       PetscCall(PetscArraycpy(dd->refine_y_hier, refy, n));
63     }
64   }
65   if (dim > 2) {
66     n = maxnlevels;
67     PetscCall(PetscOptionsIntArray("-da_refine_hierarchy_z", "Refinement factor for each level", "None", refz, &n, &flg));
68     if (flg) {
69       dd->refine_z        = refz[0];
70       dd->refine_z_hier_n = n;
71       PetscCall(PetscMalloc1(n, &dd->refine_z_hier));
72       PetscCall(PetscArraycpy(dd->refine_z_hier, refz, n));
73     }
74   }
75 
76   PetscCall(PetscOptionsBoundedInt("-da_refine", "Uniformly refine DA one or more times", "None", refine, &refine, NULL, 0));
77   PetscOptionsHeadEnd();
78 
79   while (refine--) {
80     if (dd->bx == DM_BOUNDARY_PERIODIC || dd->interptype == DMDA_Q0) {
81       PetscCall(PetscIntMultError(dd->refine_x, dd->M, &dd->M));
82     } else {
83       PetscCall(PetscIntMultError(dd->refine_x, dd->M - 1, &dd->M));
84       dd->M += 1;
85     }
86     if (dd->by == DM_BOUNDARY_PERIODIC || dd->interptype == DMDA_Q0) {
87       PetscCall(PetscIntMultError(dd->refine_y, dd->N, &dd->N));
88     } else {
89       PetscCall(PetscIntMultError(dd->refine_y, dd->N - 1, &dd->N));
90       dd->N += 1;
91     }
92     if (dd->bz == DM_BOUNDARY_PERIODIC || dd->interptype == DMDA_Q0) {
93       PetscCall(PetscIntMultError(dd->refine_z, dd->P, &dd->P));
94     } else {
95       PetscCall(PetscIntMultError(dd->refine_z, dd->P - 1, &dd->P));
96       dd->P += 1;
97     }
98     da->levelup++;
99     if (da->levelup - da->leveldown >= 0) {
100       dd->refine_x = refx[da->levelup - da->leveldown];
101       dd->refine_y = refy[da->levelup - da->leveldown];
102       dd->refine_z = refz[da->levelup - da->leveldown];
103     }
104     if (da->levelup - da->leveldown >= 1) {
105       dd->coarsen_x = refx[da->levelup - da->leveldown - 1];
106       dd->coarsen_y = refy[da->levelup - da->leveldown - 1];
107       dd->coarsen_z = refz[da->levelup - da->leveldown - 1];
108     }
109   }
110   PetscFunctionReturn(PETSC_SUCCESS);
111 }
112 
113 static PetscErrorCode DMLoad_DA(DM da, PetscViewer viewer)
114 {
115   PetscInt        dim, m, n, p, dof, swidth;
116   DMDAStencilType stencil;
117   DMBoundaryType  bx, by, bz;
118   PetscBool       coors;
119   DM              dac;
120   Vec             c;
121 
122   PetscFunctionBegin;
123   PetscCall(PetscViewerBinaryRead(viewer, &dim, 1, NULL, PETSC_INT));
124   PetscCall(PetscViewerBinaryRead(viewer, &m, 1, NULL, PETSC_INT));
125   PetscCall(PetscViewerBinaryRead(viewer, &n, 1, NULL, PETSC_INT));
126   PetscCall(PetscViewerBinaryRead(viewer, &p, 1, NULL, PETSC_INT));
127   PetscCall(PetscViewerBinaryRead(viewer, &dof, 1, NULL, PETSC_INT));
128   PetscCall(PetscViewerBinaryRead(viewer, &swidth, 1, NULL, PETSC_INT));
129   PetscCall(PetscViewerBinaryRead(viewer, &bx, 1, NULL, PETSC_ENUM));
130   PetscCall(PetscViewerBinaryRead(viewer, &by, 1, NULL, PETSC_ENUM));
131   PetscCall(PetscViewerBinaryRead(viewer, &bz, 1, NULL, PETSC_ENUM));
132   PetscCall(PetscViewerBinaryRead(viewer, &stencil, 1, NULL, PETSC_ENUM));
133 
134   PetscCall(DMSetDimension(da, dim));
135   PetscCall(DMDASetSizes(da, m, n, p));
136   PetscCall(DMDASetBoundaryType(da, bx, by, bz));
137   PetscCall(DMDASetDof(da, dof));
138   PetscCall(DMDASetStencilType(da, stencil));
139   PetscCall(DMDASetStencilWidth(da, swidth));
140   PetscCall(DMSetUp(da));
141   PetscCall(PetscViewerBinaryRead(viewer, &coors, 1, NULL, PETSC_ENUM));
142   if (coors) {
143     PetscCall(DMGetCoordinateDM(da, &dac));
144     PetscCall(DMCreateGlobalVector(dac, &c));
145     PetscCall(VecLoad(c, viewer));
146     PetscCall(DMSetCoordinates(da, c));
147     PetscCall(VecDestroy(&c));
148   }
149   PetscFunctionReturn(PETSC_SUCCESS);
150 }
151 
152 static PetscErrorCode DMCreateSubDM_DA(DM dm, PetscInt numFields, const PetscInt fields[], IS *is, DM *subdm)
153 {
154   DM_DA *da = (DM_DA *)dm->data;
155 
156   PetscFunctionBegin;
157   if (subdm) {
158     PetscSF sf;
159     Vec     coords;
160     void   *ctx;
161     /* Cannot use DMClone since the dof stuff is mixed in. Ugh
162     PetscCall(DMClone(dm, subdm)); */
163     PetscCall(DMCreate(PetscObjectComm((PetscObject)dm), subdm));
164     PetscCall(DMGetPointSF(dm, &sf));
165     PetscCall(DMSetPointSF(*subdm, sf));
166     PetscCall(DMGetApplicationContext(dm, &ctx));
167     PetscCall(DMSetApplicationContext(*subdm, ctx));
168     PetscCall(DMGetCoordinatesLocal(dm, &coords));
169     if (coords) {
170       PetscCall(DMSetCoordinatesLocal(*subdm, coords));
171     } else {
172       PetscCall(DMGetCoordinates(dm, &coords));
173       if (coords) PetscCall(DMSetCoordinates(*subdm, coords));
174     }
175 
176     PetscCall(DMSetType(*subdm, DMDA));
177     PetscCall(DMSetDimension(*subdm, dm->dim));
178     PetscCall(DMDASetSizes(*subdm, da->M, da->N, da->P));
179     PetscCall(DMDASetNumProcs(*subdm, da->m, da->n, da->p));
180     PetscCall(DMDASetBoundaryType(*subdm, da->bx, da->by, da->bz));
181     PetscCall(DMDASetDof(*subdm, numFields));
182     PetscCall(DMDASetStencilType(*subdm, da->stencil_type));
183     PetscCall(DMDASetStencilWidth(*subdm, da->s));
184     PetscCall(DMDASetOwnershipRanges(*subdm, da->lx, da->ly, da->lz));
185   }
186   if (is) {
187     PetscInt *indices, cnt = 0, dof = da->w, i, j;
188 
189     PetscCall(PetscMalloc1(da->Nlocal * numFields / dof, &indices));
190     for (i = da->base / dof; i < (da->base + da->Nlocal) / dof; ++i) {
191       for (j = 0; j < numFields; ++j) indices[cnt++] = dof * i + fields[j];
192     }
193     PetscCheck(cnt == da->Nlocal * numFields / dof, PETSC_COMM_SELF, PETSC_ERR_PLIB, "Count %" PetscInt_FMT " does not equal expected value %" PetscInt_FMT, cnt, da->Nlocal * numFields / dof);
194     PetscCall(ISCreateGeneral(PetscObjectComm((PetscObject)dm), cnt, indices, PETSC_OWN_POINTER, is));
195   }
196   PetscFunctionReturn(PETSC_SUCCESS);
197 }
198 
199 static PetscErrorCode DMCreateFieldDecomposition_DA(DM dm, PetscInt *len, char ***namelist, IS **islist, DM **dmlist)
200 {
201   PetscInt i;
202   DM_DA   *dd  = (DM_DA *)dm->data;
203   PetscInt dof = dd->w;
204 
205   PetscFunctionBegin;
206   if (len) *len = dof;
207   if (islist) {
208     Vec      v;
209     PetscInt rstart, n;
210 
211     PetscCall(DMGetGlobalVector(dm, &v));
212     PetscCall(VecGetOwnershipRange(v, &rstart, NULL));
213     PetscCall(VecGetLocalSize(v, &n));
214     PetscCall(DMRestoreGlobalVector(dm, &v));
215     PetscCall(PetscMalloc1(dof, islist));
216     for (i = 0; i < dof; i++) PetscCall(ISCreateStride(PetscObjectComm((PetscObject)dm), n / dof, rstart + i, dof, &(*islist)[i]));
217   }
218   if (namelist) {
219     PetscCall(PetscMalloc1(dof, namelist));
220     if (dd->fieldname) {
221       for (i = 0; i < dof; i++) PetscCall(PetscStrallocpy(dd->fieldname[i], &(*namelist)[i]));
222     } else SETERRQ(PETSC_COMM_SELF, PETSC_ERR_SUP, "Currently DMDA must have fieldnames");
223   }
224   if (dmlist) {
225     DM da;
226 
227     PetscCall(DMDACreate(PetscObjectComm((PetscObject)dm), &da));
228     PetscCall(DMSetDimension(da, dm->dim));
229     PetscCall(DMDASetSizes(da, dd->M, dd->N, dd->P));
230     PetscCall(DMDASetNumProcs(da, dd->m, dd->n, dd->p));
231     PetscCall(DMDASetBoundaryType(da, dd->bx, dd->by, dd->bz));
232     PetscCall(DMDASetDof(da, 1));
233     PetscCall(DMDASetStencilType(da, dd->stencil_type));
234     PetscCall(DMDASetStencilWidth(da, dd->s));
235     PetscCall(DMSetUp(da));
236     PetscCall(PetscMalloc1(dof, dmlist));
237     for (i = 0; i < dof - 1; i++) PetscCall(PetscObjectReference((PetscObject)da));
238     for (i = 0; i < dof; i++) (*dmlist)[i] = da;
239   }
240   PetscFunctionReturn(PETSC_SUCCESS);
241 }
242 
243 static PetscErrorCode DMClone_DA(DM dm, DM *newdm)
244 {
245   DM_DA *da = (DM_DA *)dm->data;
246 
247   PetscFunctionBegin;
248   PetscCall(DMSetType(*newdm, DMDA));
249   PetscCall(DMSetDimension(*newdm, dm->dim));
250   PetscCall(DMDASetSizes(*newdm, da->M, da->N, da->P));
251   PetscCall(DMDASetNumProcs(*newdm, da->m, da->n, da->p));
252   PetscCall(DMDASetBoundaryType(*newdm, da->bx, da->by, da->bz));
253   PetscCall(DMDASetDof(*newdm, da->w));
254   PetscCall(DMDASetStencilType(*newdm, da->stencil_type));
255   PetscCall(DMDASetStencilWidth(*newdm, da->s));
256   PetscCall(DMDASetOwnershipRanges(*newdm, da->lx, da->ly, da->lz));
257   PetscCall(DMSetUp(*newdm));
258   PetscFunctionReturn(PETSC_SUCCESS);
259 }
260 
261 static PetscErrorCode DMHasCreateInjection_DA(DM dm, PetscBool *flg)
262 {
263   DM_DA *da = (DM_DA *)dm->data;
264 
265   PetscFunctionBegin;
266   PetscValidHeaderSpecific(dm, DM_CLASSID, 1);
267   PetscAssertPointer(flg, 2);
268   *flg = da->interptype == DMDA_Q1 ? PETSC_TRUE : PETSC_FALSE;
269   PetscFunctionReturn(PETSC_SUCCESS);
270 }
271 
272 static PetscErrorCode DMGetDimPoints_DA(DM dm, PetscInt dim, PetscInt *pStart, PetscInt *pEnd)
273 {
274   PetscFunctionBegin;
275   PetscCall(DMDAGetDepthStratum(dm, dim, pStart, pEnd));
276   PetscFunctionReturn(PETSC_SUCCESS);
277 }
278 
279 static PetscErrorCode DMGetNeighbors_DA(DM dm, PetscInt *nranks, const PetscMPIInt *ranks[])
280 {
281   PetscInt        dim;
282   DMDAStencilType st;
283 
284   PetscFunctionBegin;
285   PetscCall(DMDAGetNeighbors(dm, ranks));
286   PetscCall(DMDAGetInfo(dm, &dim, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, &st));
287 
288   switch (dim) {
289   case 1:
290     *nranks = 3;
291     /* if (st == DMDA_STENCIL_STAR) *nranks = 3; */
292     break;
293   case 2:
294     *nranks = 9;
295     /* if (st == DMDA_STENCIL_STAR) *nranks = 5; */
296     break;
297   case 3:
298     *nranks = 27;
299     /* if (st == DMDA_STENCIL_STAR) *nranks = 7; */
300     break;
301   default:
302     break;
303   }
304   PetscFunctionReturn(PETSC_SUCCESS);
305 }
306 
307 /*MC
308    DMDA = "da" - A `DM` object that is used to manage data for a structured grid in 1, 2, or 3 dimensions.
309          In the global representation of the vector each process stores a non-overlapping rectangular (or slab in 3d) portion of the grid points.
310          In the local representation these rectangular regions (slabs) are extended in all directions by a stencil width set with `DMDASetStencilWidth()`.
311 
312          The vectors can be thought of as either cell centered or vertex centered on the mesh. But some variables cannot be cell centered and others
313          vertex centered; see the documentation for `DMSTAG`, a similar `DM` implementation which supports more general staggered grids.
314 
315   Level: intermediate
316 
317 .seealso: [](sec_struct), `DMType`, `DMCOMPOSITE`, `DMSTAG`, `DMDACreate()`, `DMCreate()`, `DMSetType()`, `DMDASetStencilWidth()`, `DMDASetStencilType()`,
318           `DMDAStencilType`
319 M*/
320 
321 PETSC_EXTERN PetscErrorCode DMCreate_DA(DM da)
322 {
323   DM_DA *dd;
324 
325   PetscFunctionBegin;
326   PetscAssertPointer(da, 1);
327   PetscCall(PetscNew(&dd));
328   da->data = dd;
329 
330   da->dim        = -1;
331   dd->interptype = DMDA_Q1;
332   dd->refine_x   = 2;
333   dd->refine_y   = 2;
334   dd->refine_z   = 2;
335   dd->coarsen_x  = 2;
336   dd->coarsen_y  = 2;
337   dd->coarsen_z  = 2;
338   dd->fieldname  = NULL;
339   dd->nlocal     = -1;
340   dd->Nlocal     = -1;
341   dd->M          = -1;
342   dd->N          = -1;
343   dd->P          = -1;
344   dd->m          = -1;
345   dd->n          = -1;
346   dd->p          = -1;
347   dd->w          = -1;
348   dd->s          = -1;
349 
350   dd->xs = -1;
351   dd->xe = -1;
352   dd->ys = -1;
353   dd->ye = -1;
354   dd->zs = -1;
355   dd->ze = -1;
356   dd->Xs = -1;
357   dd->Xe = -1;
358   dd->Ys = -1;
359   dd->Ye = -1;
360   dd->Zs = -1;
361   dd->Ze = -1;
362 
363   dd->Nsub = 1;
364   dd->xol  = 0;
365   dd->yol  = 0;
366   dd->zol  = 0;
367   dd->xo   = 0;
368   dd->yo   = 0;
369   dd->zo   = 0;
370   dd->Mo   = -1;
371   dd->No   = -1;
372   dd->Po   = -1;
373 
374   dd->gtol = NULL;
375   dd->ltol = NULL;
376   dd->ao   = NULL;
377   PetscCall(PetscStrallocpy(AOBASIC, (char **)&dd->aotype));
378   dd->base         = -1;
379   dd->bx           = DM_BOUNDARY_NONE;
380   dd->by           = DM_BOUNDARY_NONE;
381   dd->bz           = DM_BOUNDARY_NONE;
382   dd->stencil_type = DMDA_STENCIL_BOX;
383   dd->interptype   = DMDA_Q1;
384   dd->lx           = NULL;
385   dd->ly           = NULL;
386   dd->lz           = NULL;
387 
388   dd->elementtype = DMDA_ELEMENT_Q1;
389 
390   da->ops->globaltolocalbegin        = DMGlobalToLocalBegin_DA;
391   da->ops->globaltolocalend          = DMGlobalToLocalEnd_DA;
392   da->ops->localtoglobalbegin        = DMLocalToGlobalBegin_DA;
393   da->ops->localtoglobalend          = DMLocalToGlobalEnd_DA;
394   da->ops->localtolocalbegin         = DMLocalToLocalBegin_DA;
395   da->ops->localtolocalend           = DMLocalToLocalEnd_DA;
396   da->ops->createglobalvector        = DMCreateGlobalVector_DA;
397   da->ops->createlocalvector         = DMCreateLocalVector_DA;
398   da->ops->createinterpolation       = DMCreateInterpolation_DA;
399   da->ops->getcoloring               = DMCreateColoring_DA;
400   da->ops->creatematrix              = DMCreateMatrix_DA;
401   da->ops->refine                    = DMRefine_DA;
402   da->ops->coarsen                   = DMCoarsen_DA;
403   da->ops->refinehierarchy           = DMRefineHierarchy_DA;
404   da->ops->coarsenhierarchy          = DMCoarsenHierarchy_DA;
405   da->ops->createinjection           = DMCreateInjection_DA;
406   da->ops->hascreateinjection        = DMHasCreateInjection_DA;
407   da->ops->destroy                   = DMDestroy_DA;
408   da->ops->view                      = NULL;
409   da->ops->setfromoptions            = DMSetFromOptions_DA;
410   da->ops->setup                     = DMSetUp_DA;
411   da->ops->clone                     = DMClone_DA;
412   da->ops->load                      = DMLoad_DA;
413   da->ops->createcoordinatedm        = DMCreateCoordinateDM_DA;
414   da->ops->createsubdm               = DMCreateSubDM_DA;
415   da->ops->createfielddecomposition  = DMCreateFieldDecomposition_DA;
416   da->ops->createdomaindecomposition = DMCreateDomainDecomposition_DA;
417   da->ops->createddscatters          = DMCreateDomainDecompositionScatters_DA;
418   da->ops->getdimpoints              = DMGetDimPoints_DA;
419   da->ops->getneighbors              = DMGetNeighbors_DA;
420   da->ops->locatepoints              = DMLocatePoints_DA_Regular;
421   da->ops->getcompatibility          = DMGetCompatibility_DA;
422   PetscCall(PetscObjectComposeFunction((PetscObject)da, "DMSetUpGLVisViewer_C", DMSetUpGLVisViewer_DMDA));
423   PetscFunctionReturn(PETSC_SUCCESS);
424 }
425 
426 /*@
427   DMDACreate - Creates a `DMDA` object for managing structured grids.
428 
429   Collective
430 
431   Input Parameter:
432 . comm - The communicator for the `DMDA` object
433 
434   Output Parameter:
435 . da - The DMDA object
436 
437   Level: advanced
438 
439   Developer Note:
440   Since there exists DMDACreate1/2/3d() should this routine even exist?
441 
442 .seealso: [](sec_struct), `DMDASetSizes()`, `DMClone()`, `DMDACreate1d()`, `DMDACreate2d()`, `DMDACreate3d()`
443 @*/
444 PetscErrorCode DMDACreate(MPI_Comm comm, DM *da)
445 {
446   PetscFunctionBegin;
447   PetscAssertPointer(da, 2);
448   PetscCall(DMCreate(comm, da));
449   PetscCall(DMSetType(*da, DMDA));
450   PetscFunctionReturn(PETSC_SUCCESS);
451 }
452