xref: /petsc/src/dm/interface/dmi.c (revision 4e97f8ebb84dd841ee7d0d48926a4de5d5170225)
1 #include <petsc/private/dmimpl.h>     /*I      "petscdm.h"     I*/
2 #include <petscds.h>
3 
4 PetscErrorCode DMCreateGlobalVector_Section_Private(DM dm,Vec *vec)
5 {
6   PetscSection   gSection;
7   PetscInt       localSize, bs, blockSize = -1, pStart, pEnd, p;
8   PetscErrorCode ierr;
9   PetscInt       in[2],out[2];
10 
11   PetscFunctionBegin;
12   ierr = DMGetGlobalSection(dm, &gSection);CHKERRQ(ierr);
13   ierr = PetscSectionGetChart(gSection, &pStart, &pEnd);CHKERRQ(ierr);
14   for (p = pStart; p < pEnd; ++p) {
15     PetscInt dof, cdof;
16 
17     ierr = PetscSectionGetDof(gSection, p, &dof);CHKERRQ(ierr);
18     ierr = PetscSectionGetConstraintDof(gSection, p, &cdof);CHKERRQ(ierr);
19 
20     if (dof > 0) {
21       if (blockSize < 0 && dof-cdof > 0) {
22         /* set blockSize */
23         blockSize = dof-cdof;
24       } else if (dof-cdof != blockSize) {
25         /* non-identical blockSize, set it as 1 */
26         blockSize = 1;
27         break;
28       }
29     }
30   }
31 
32   in[0] = blockSize < 0 ? PETSC_MIN_INT : -blockSize;
33   in[1] = blockSize;
34   ierr = MPIU_Allreduce(in,out,2,MPIU_INT,MPI_MAX,PetscObjectComm((PetscObject)dm));CHKERRQ(ierr);
35   /* -out[0] = min(blockSize), out[1] = max(blockSize) */
36   if (-out[0] == out[1]) {
37     bs = out[1];
38   } else bs = 1;
39 
40   if (bs < 0) { /* Everyone was empty */
41     blockSize = 1;
42     bs        = 1;
43   }
44 
45   ierr = PetscSectionGetConstrainedStorageSize(gSection, &localSize);CHKERRQ(ierr);
46   if (localSize%blockSize) SETERRQ2(PetscObjectComm((PetscObject)dm), PETSC_ERR_ARG_WRONG, "Mismatch between blocksize %d and local storage size %d", blockSize, localSize);
47   ierr = VecCreate(PetscObjectComm((PetscObject)dm), vec);CHKERRQ(ierr);
48   ierr = VecSetSizes(*vec, localSize, PETSC_DETERMINE);CHKERRQ(ierr);
49   ierr = VecSetBlockSize(*vec, bs);CHKERRQ(ierr);
50   ierr = VecSetType(*vec,dm->vectype);CHKERRQ(ierr);
51   ierr = VecSetDM(*vec, dm);CHKERRQ(ierr);
52   /* ierr = VecSetLocalToGlobalMapping(*vec, dm->ltogmap);CHKERRQ(ierr); */
53   PetscFunctionReturn(0);
54 }
55 
56 PetscErrorCode DMCreateLocalVector_Section_Private(DM dm,Vec *vec)
57 {
58   PetscSection   section;
59   PetscInt       localSize, blockSize = -1, pStart, pEnd, p;
60   PetscErrorCode ierr;
61 
62   PetscFunctionBegin;
63   ierr = DMGetSection(dm, &section);CHKERRQ(ierr);
64   ierr = PetscSectionGetChart(section, &pStart, &pEnd);CHKERRQ(ierr);
65   for (p = pStart; p < pEnd; ++p) {
66     PetscInt dof;
67 
68     ierr = PetscSectionGetDof(section, p, &dof);CHKERRQ(ierr);
69     if ((blockSize < 0) && (dof > 0)) blockSize = dof;
70     if ((dof > 0) && (dof != blockSize)) {
71       blockSize = 1;
72       break;
73     }
74   }
75   ierr = PetscSectionGetStorageSize(section, &localSize);CHKERRQ(ierr);
76   ierr = VecCreate(PETSC_COMM_SELF, vec);CHKERRQ(ierr);
77   ierr = VecSetSizes(*vec, localSize, localSize);CHKERRQ(ierr);
78   ierr = VecSetBlockSize(*vec, blockSize);CHKERRQ(ierr);
79   ierr = VecSetType(*vec,dm->vectype);CHKERRQ(ierr);
80   ierr = VecSetDM(*vec, dm);CHKERRQ(ierr);
81   PetscFunctionReturn(0);
82 }
83 
84 /*@C
85   DMCreateSectionSubDM - Returns an IS and subDM+subSection encapsulating a subproblem defined by the fields in a PetscSection in the DM.
86 
87   Not collective
88 
89   Input Parameters:
90 + dm        - The DM object
91 . numFields - The number of fields in this subproblem
92 - fields    - The field numbers of the selected fields
93 
94   Output Parameters:
95 + is - The global indices for the subproblem
96 - subdm - The DM for the subproblem, which must already have be cloned from dm
97 
98   Note: This handles all information in the DM class and the PetscSection. This is used as the basis for creating subDMs in specialized classes,
99   such as Plex and Forest.
100 
101   Level: intermediate
102 
103 .seealso DMCreateSubDM(), DMGetSection(), DMPlexSetMigrationSF(), DMView()
104 @*/
105 PetscErrorCode DMCreateSectionSubDM(DM dm, PetscInt numFields, const PetscInt fields[], IS *is, DM *subdm)
106 {
107   PetscSection   section, sectionGlobal;
108   PetscInt      *subIndices;
109   PetscInt       subSize = 0, subOff = 0, Nf, f, pStart, pEnd, p;
110   PetscErrorCode ierr;
111 
112   PetscFunctionBegin;
113   if (!numFields) PetscFunctionReturn(0);
114   ierr = DMGetSection(dm, &section);CHKERRQ(ierr);
115   ierr = DMGetGlobalSection(dm, &sectionGlobal);CHKERRQ(ierr);
116   if (!section) SETERRQ(PetscObjectComm((PetscObject)dm), PETSC_ERR_ARG_WRONG, "Must set default section for DM before splitting fields");
117   if (!sectionGlobal) SETERRQ(PetscObjectComm((PetscObject)dm), PETSC_ERR_ARG_WRONG, "Must set default global section for DM before splitting fields");
118   ierr = PetscSectionGetNumFields(section, &Nf);CHKERRQ(ierr);
119   if (numFields > Nf) SETERRQ2(PetscObjectComm((PetscObject)dm), PETSC_ERR_ARG_WRONG, "Number of requested fields %d greater than number of DM fields %d", numFields, Nf);
120   if (is) {
121     PetscInt bs, bsLocal[2], bsMinMax[2];
122 
123     for (f = 0, bs = 0; f < numFields; ++f) {
124       PetscInt Nc;
125 
126       ierr = PetscSectionGetFieldComponents(section, fields[f], &Nc);CHKERRQ(ierr);
127       bs  += Nc;
128     }
129     ierr = PetscSectionGetChart(sectionGlobal, &pStart, &pEnd);CHKERRQ(ierr);
130     for (p = pStart; p < pEnd; ++p) {
131       PetscInt gdof, pSubSize  = 0;
132 
133       ierr = PetscSectionGetDof(sectionGlobal, p, &gdof);CHKERRQ(ierr);
134       if (gdof > 0) {
135         for (f = 0; f < numFields; ++f) {
136           PetscInt fdof, fcdof;
137 
138           ierr     = PetscSectionGetFieldDof(section, p, fields[f], &fdof);CHKERRQ(ierr);
139           ierr     = PetscSectionGetFieldConstraintDof(section, p, fields[f], &fcdof);CHKERRQ(ierr);
140           pSubSize += fdof-fcdof;
141         }
142         subSize += pSubSize;
143         if (pSubSize && bs != pSubSize) {
144           /* Layout does not admit a pointwise block size */
145           bs = 1;
146         }
147       }
148     }
149     /* Must have same blocksize on all procs (some might have no points) */
150     bsLocal[0] = bs < 0 ? PETSC_MAX_INT : bs; bsLocal[1] = bs;
151     ierr = PetscGlobalMinMaxInt(PetscObjectComm((PetscObject) dm), bsLocal, bsMinMax);CHKERRQ(ierr);
152     if (bsMinMax[0] != bsMinMax[1]) {bs = 1;}
153     else                            {bs = bsMinMax[0];}
154     ierr = PetscMalloc1(subSize, &subIndices);CHKERRQ(ierr);
155     for (p = pStart; p < pEnd; ++p) {
156       PetscInt gdof, goff;
157 
158       ierr = PetscSectionGetDof(sectionGlobal, p, &gdof);CHKERRQ(ierr);
159       if (gdof > 0) {
160         ierr = PetscSectionGetOffset(sectionGlobal, p, &goff);CHKERRQ(ierr);
161         for (f = 0; f < numFields; ++f) {
162           PetscInt fdof, fcdof, fc, f2, poff = 0;
163 
164           /* Can get rid of this loop by storing field information in the global section */
165           for (f2 = 0; f2 < fields[f]; ++f2) {
166             ierr  = PetscSectionGetFieldDof(section, p, f2, &fdof);CHKERRQ(ierr);
167             ierr  = PetscSectionGetFieldConstraintDof(section, p, f2, &fcdof);CHKERRQ(ierr);
168             poff += fdof-fcdof;
169           }
170           ierr = PetscSectionGetFieldDof(section, p, fields[f], &fdof);CHKERRQ(ierr);
171           ierr = PetscSectionGetFieldConstraintDof(section, p, fields[f], &fcdof);CHKERRQ(ierr);
172           for (fc = 0; fc < fdof-fcdof; ++fc, ++subOff) {
173             subIndices[subOff] = goff+poff+fc;
174           }
175         }
176       }
177     }
178     ierr = ISCreateGeneral(PetscObjectComm((PetscObject)dm), subSize, subIndices, PETSC_OWN_POINTER, is);CHKERRQ(ierr);
179     if (bs > 1) {
180       /* We need to check that the block size does not come from non-contiguous fields */
181       PetscInt i, j, set = 1;
182       for (i = 0; i < subSize; i += bs) {
183         for (j = 0; j < bs; ++j) {
184           if (subIndices[i+j] != subIndices[i]+j) {set = 0; break;}
185         }
186       }
187       if (set) {ierr = ISSetBlockSize(*is, bs);CHKERRQ(ierr);}
188     }
189   }
190   if (subdm) {
191     PetscSection subsection;
192     PetscBool    haveNull = PETSC_FALSE;
193     PetscInt     f, nf = 0;
194 
195     ierr = PetscSectionCreateSubsection(section, numFields, fields, &subsection);CHKERRQ(ierr);
196     ierr = DMSetSection(*subdm, subsection);CHKERRQ(ierr);
197     ierr = PetscSectionDestroy(&subsection);CHKERRQ(ierr);
198     for (f = 0; f < numFields; ++f) {
199       (*subdm)->nullspaceConstructors[f] = dm->nullspaceConstructors[fields[f]];
200       if ((*subdm)->nullspaceConstructors[f]) {
201         haveNull = PETSC_TRUE;
202         nf       = f;
203       }
204     }
205     if (haveNull && is) {
206       MatNullSpace nullSpace;
207 
208       ierr = (*(*subdm)->nullspaceConstructors[nf])(*subdm, nf, &nullSpace);CHKERRQ(ierr);
209       ierr = PetscObjectCompose((PetscObject) *is, "nullspace", (PetscObject) nullSpace);CHKERRQ(ierr);
210       ierr = MatNullSpaceDestroy(&nullSpace);CHKERRQ(ierr);
211     }
212     if (dm->probs) {
213       ierr = DMSetNumFields(*subdm, numFields);CHKERRQ(ierr);
214       for (f = 0; f < numFields; ++f) {
215         PetscObject disc;
216 
217         ierr = DMGetField(dm, fields[f], NULL, &disc);CHKERRQ(ierr);
218         ierr = DMSetField(*subdm, f, NULL, disc);CHKERRQ(ierr);
219       }
220       ierr = DMCreateDS(*subdm);CHKERRQ(ierr);
221       if (numFields == 1 && is) {
222         PetscObject disc, space, pmat;
223 
224         ierr = DMGetField(*subdm, 0, NULL, &disc);CHKERRQ(ierr);
225         ierr = PetscObjectQuery(disc, "nullspace", &space);CHKERRQ(ierr);
226         if (space) {ierr = PetscObjectCompose((PetscObject) *is, "nullspace", space);CHKERRQ(ierr);}
227         ierr = PetscObjectQuery(disc, "nearnullspace", &space);CHKERRQ(ierr);
228         if (space) {ierr = PetscObjectCompose((PetscObject) *is, "nearnullspace", space);CHKERRQ(ierr);}
229         ierr = PetscObjectQuery(disc, "pmat", &pmat);CHKERRQ(ierr);
230         if (pmat) {ierr = PetscObjectCompose((PetscObject) *is, "pmat", pmat);CHKERRQ(ierr);}
231       }
232       ierr = PetscDSCopyConstants(dm->probs[0].ds, (*subdm)->probs[0].ds);CHKERRQ(ierr);
233       ierr = PetscDSCopyBoundary(dm->probs[0].ds, (*subdm)->probs[0].ds);CHKERRQ(ierr);
234       ierr = PetscDSSelectEquations(dm->probs[0].ds, numFields, fields, (*subdm)->probs[0].ds);CHKERRQ(ierr);
235     }
236     if (dm->coarseMesh) {
237       ierr = DMCreateSubDM(dm->coarseMesh, numFields, fields, NULL, &(*subdm)->coarseMesh);CHKERRQ(ierr);
238     }
239   }
240   PetscFunctionReturn(0);
241 }
242 
243 /*@C
244   DMCreateSectionSuperDM - Returns an arrays of ISes and DM+Section encapsulating a superproblem defined by the DM+Sections passed in.
245 
246   Not collective
247 
248   Input Parameter:
249 + dms - The DM objects
250 - len - The number of DMs
251 
252   Output Parameters:
253 + is - The global indices for the subproblem, or NULL
254 - superdm - The DM for the superproblem, which must already have be cloned
255 
256   Note: This handles all information in the DM class and the PetscSection. This is used as the basis for creating subDMs in specialized classes,
257   such as Plex and Forest.
258 
259   Level: intermediate
260 
261 .seealso DMCreateSuperDM(), DMGetSection(), DMPlexSetMigrationSF(), DMView()
262 @*/
263 PetscErrorCode DMCreateSectionSuperDM(DM dms[], PetscInt len, IS **is, DM *superdm)
264 {
265   MPI_Comm       comm;
266   PetscSection   supersection, *sections, *sectionGlobals;
267   PetscInt      *Nfs, Nf = 0, f, supf, nullf = -1, i;
268   PetscBool      haveNull = PETSC_FALSE;
269   PetscErrorCode ierr;
270 
271   PetscFunctionBegin;
272   ierr = PetscObjectGetComm((PetscObject)dms[0], &comm);CHKERRQ(ierr);
273   /* Pull out local and global sections */
274   ierr = PetscMalloc3(len, &Nfs, len, &sections, len, &sectionGlobals);CHKERRQ(ierr);
275   for (i = 0 ; i < len; ++i) {
276     ierr = DMGetSection(dms[i], &sections[i]);CHKERRQ(ierr);
277     ierr = DMGetGlobalSection(dms[i], &sectionGlobals[i]);CHKERRQ(ierr);
278     if (!sections[i]) SETERRQ(comm, PETSC_ERR_ARG_WRONG, "Must set default section for DM before splitting fields");
279     if (!sectionGlobals[i]) SETERRQ(comm, PETSC_ERR_ARG_WRONG, "Must set default global section for DM before splitting fields");
280     ierr = PetscSectionGetNumFields(sections[i], &Nfs[i]);CHKERRQ(ierr);
281     Nf += Nfs[i];
282   }
283   /* Create the supersection */
284   ierr = PetscSectionCreateSupersection(sections, len, &supersection);CHKERRQ(ierr);
285   ierr = DMSetSection(*superdm, supersection);CHKERRQ(ierr);
286   /* Create ISes */
287   if (is) {
288     PetscSection supersectionGlobal;
289     PetscInt     bs = -1, startf = 0;
290 
291     ierr = PetscMalloc1(len, is);CHKERRQ(ierr);
292     ierr = DMGetDefaultGlobalSection(*superdm, &supersectionGlobal);CHKERRQ(ierr);
293     for (i = 0 ; i < len; startf += Nfs[i], ++i) {
294       PetscInt *subIndices;
295       PetscInt  subSize, subOff, pStart, pEnd, p, start, end, dummy;
296 
297       ierr = PetscSectionGetChart(sectionGlobals[i], &pStart, &pEnd);CHKERRQ(ierr);
298       ierr = PetscSectionGetConstrainedStorageSize(sectionGlobals[i], &subSize);CHKERRQ(ierr);
299       ierr = PetscMalloc1(subSize, &subIndices);CHKERRQ(ierr);
300       for (p = pStart, subOff = 0; p < pEnd; ++p) {
301         PetscInt gdof, gcdof, gtdof, d;
302 
303         ierr = PetscSectionGetDof(sectionGlobals[i], p, &gdof);CHKERRQ(ierr);
304         ierr = PetscSectionGetConstraintDof(sections[i], p, &gcdof);CHKERRQ(ierr);
305         gtdof = gdof - gcdof;
306         if (gdof > 0 && gtdof) {
307           if (bs < 0)           {bs = gtdof;}
308           else if (bs != gtdof) {bs = 1;}
309           ierr = DMGetGlobalFieldOffset_Private(*superdm, p, startf, &start, &dummy);CHKERRQ(ierr);
310           ierr = DMGetGlobalFieldOffset_Private(*superdm, p, startf+Nfs[i]-1, &dummy, &end);CHKERRQ(ierr);
311           if (end-start != gtdof) SETERRQ4(PETSC_COMM_SELF, PETSC_ERR_ARG_SIZ, "Invalid number of global dofs %D != %D for dm %D on point %D", end-start, gtdof, i, p);
312           for (d = start; d < end; ++d, ++subOff) subIndices[subOff] = d;
313         }
314       }
315       ierr = ISCreateGeneral(comm, subSize, subIndices, PETSC_OWN_POINTER, &(*is)[i]);CHKERRQ(ierr);
316       /* Must have same blocksize on all procs (some might have no points) */
317       {
318         PetscInt bs = -1, bsLocal[2], bsMinMax[2];
319 
320         bsLocal[0] = bs < 0 ? PETSC_MAX_INT : bs; bsLocal[1] = bs;
321         ierr = PetscGlobalMinMaxInt(comm, bsLocal, bsMinMax);CHKERRQ(ierr);
322         if (bsMinMax[0] != bsMinMax[1]) {bs = 1;}
323         else                            {bs = bsMinMax[0];}
324         ierr = ISSetBlockSize((*is)[i], bs);CHKERRQ(ierr);
325       }
326     }
327   }
328   /* Preserve discretizations */
329   if (len && dms[0]->probs) {
330     ierr = DMSetNumFields(*superdm, Nf);CHKERRQ(ierr);
331     for (i = 0, supf = 0; i < len; ++i) {
332       for (f = 0; f < Nfs[i]; ++f, ++supf) {
333         PetscObject disc;
334 
335         ierr = DMGetField(dms[i], f, NULL, &disc);CHKERRQ(ierr);
336         ierr = DMSetField(*superdm, supf, NULL, disc);CHKERRQ(ierr);
337       }
338     }
339     ierr = DMCreateDS(*superdm);CHKERRQ(ierr);
340   }
341   /* Preserve nullspaces */
342   for (i = 0, supf = 0; i < len; ++i) {
343     for (f = 0; f < Nfs[i]; ++f, ++supf) {
344       (*superdm)->nullspaceConstructors[supf] = dms[i]->nullspaceConstructors[f];
345       if ((*superdm)->nullspaceConstructors[supf]) {
346         haveNull = PETSC_TRUE;
347         nullf    = supf;
348       }
349     }
350   }
351   /* Attach nullspace to IS */
352   if (haveNull && is) {
353     MatNullSpace nullSpace;
354 
355     ierr = (*(*superdm)->nullspaceConstructors[nullf])(*superdm, nullf, &nullSpace);CHKERRQ(ierr);
356     ierr = PetscObjectCompose((PetscObject) (*is)[nullf], "nullspace", (PetscObject) nullSpace);CHKERRQ(ierr);
357     ierr = MatNullSpaceDestroy(&nullSpace);CHKERRQ(ierr);
358   }
359   ierr = PetscSectionDestroy(&supersection);CHKERRQ(ierr);
360   ierr = PetscFree3(Nfs, sections, sectionGlobals);CHKERRQ(ierr);
361   PetscFunctionReturn(0);
362 }
363