xref: /petsc/src/dm/impls/composite/pack.c (revision 7de857017fb4f4a723783e108e86dcff7a089475)
1 
2 #include "packimpl.h" /*I   "petscdmcomposite.h"   I*/
3 
4 #undef __FUNCT__
5 #define __FUNCT__ "DMCompositeSetCoupling"
6 /*@C
7     DMCompositeSetCoupling - Sets user provided routines that compute the coupling between the
8       seperate components (DMs) in a DMto build the correct matrix nonzero structure.
9 
10 
11     Logically Collective on MPI_Comm
12 
13     Input Parameter:
14 +   dm - the composite object
15 -   formcouplelocations - routine to set the nonzero locations in the matrix
16 
17     Level: advanced
18 
19     Notes: See DMSetApplicationContext() and DMGetApplicationContext() for how to get user information into
20         this routine
21 
22 @*/
23 PetscErrorCode  DMCompositeSetCoupling(DM dm,PetscErrorCode (*FormCoupleLocations)(DM,Mat,PetscInt*,PetscInt*,PetscInt,PetscInt,PetscInt,PetscInt))
24 {
25   DM_Composite *com = (DM_Composite*)dm->data;
26 
27   PetscFunctionBegin;
28   com->FormCoupleLocations = FormCoupleLocations;
29   PetscFunctionReturn(0);
30 }
31 
32 #undef __FUNCT__
33 #define __FUNCT__ "DMDestroy_Composite"
34 PetscErrorCode  DMDestroy_Composite(DM dm)
35 {
36   PetscErrorCode         ierr;
37   struct DMCompositeLink *next, *prev;
38   DM_Composite           *com = (DM_Composite *)dm->data;
39 
40   PetscFunctionBegin;
41   next = com->next;
42   while (next) {
43     prev = next;
44     next = next->next;
45     ierr = DMDestroy(&prev->dm);CHKERRQ(ierr);
46     ierr = PetscFree(prev->grstarts);CHKERRQ(ierr);
47     ierr = PetscFree(prev);CHKERRQ(ierr);
48   }
49   PetscFunctionReturn(0);
50 }
51 
52 #undef __FUNCT__
53 #define __FUNCT__ "DMView_Composite"
54 PetscErrorCode  DMView_Composite(DM dm,PetscViewer v)
55 {
56   PetscErrorCode ierr;
57   PetscBool      iascii;
58   DM_Composite   *com = (DM_Composite *)dm->data;
59 
60   PetscFunctionBegin;
61   ierr = PetscTypeCompare((PetscObject)v,PETSCVIEWERASCII,&iascii);CHKERRQ(ierr);
62   if (iascii) {
63     struct DMCompositeLink *lnk = com->next;
64     PetscInt               i;
65 
66     ierr = PetscViewerASCIIPrintf(v,"DM (%s)\n",((PetscObject)dm)->prefix?((PetscObject)dm)->prefix:"no prefix");CHKERRQ(ierr);
67     ierr = PetscViewerASCIIPrintf(v,"  contains %D DMs\n",com->nDM);CHKERRQ(ierr);
68     ierr = PetscViewerASCIIPushTab(v);CHKERRQ(ierr);
69     for (i=0; lnk; lnk=lnk->next,i++) {
70       ierr = PetscViewerASCIIPrintf(v,"Link %D: DM of type %s\n",i,((PetscObject)lnk->dm)->type_name);CHKERRQ(ierr);
71       ierr = PetscViewerASCIIPushTab(v);CHKERRQ(ierr);
72       ierr = DMView(lnk->dm,v);CHKERRQ(ierr);
73       ierr = PetscViewerASCIIPopTab(v);CHKERRQ(ierr);
74     }
75     ierr = PetscViewerASCIIPopTab(v);CHKERRQ(ierr);
76   }
77   PetscFunctionReturn(0);
78 }
79 
80 /* --------------------------------------------------------------------------------------*/
81 #undef __FUNCT__
82 #define __FUNCT__ "DMSetUp_Composite"
83 PetscErrorCode  DMSetUp_Composite(DM dm)
84 {
85   PetscErrorCode         ierr;
86   PetscInt               nprev = 0;
87   PetscMPIInt            rank,size;
88   DM_Composite           *com = (DM_Composite*)dm->data;
89   struct DMCompositeLink *next = com->next;
90   PetscLayout            map;
91 
92   PetscFunctionBegin;
93   if (com->setup) SETERRQ(((PetscObject)dm)->comm,PETSC_ERR_ARG_WRONGSTATE,"Packer has already been setup");
94   ierr = PetscLayoutCreate(((PetscObject)dm)->comm,&map);CHKERRQ(ierr);
95   ierr = PetscLayoutSetLocalSize(map,com->n);CHKERRQ(ierr);
96   ierr = PetscLayoutSetSize(map,PETSC_DETERMINE);CHKERRQ(ierr);
97   ierr = PetscLayoutSetBlockSize(map,1);CHKERRQ(ierr);
98   ierr = PetscLayoutSetUp(map);CHKERRQ(ierr);
99   ierr = PetscLayoutGetSize(map,&com->N);CHKERRQ(ierr);
100   ierr = PetscLayoutGetRange(map,&com->rstart,PETSC_NULL);CHKERRQ(ierr);
101   ierr = PetscLayoutDestroy(&map);CHKERRQ(ierr);
102 
103   /* now set the rstart for each linked vector */
104   ierr = MPI_Comm_rank(((PetscObject)dm)->comm,&rank);CHKERRQ(ierr);
105   ierr = MPI_Comm_size(((PetscObject)dm)->comm,&size);CHKERRQ(ierr);
106   while (next) {
107     next->rstart = nprev;
108     nprev += next->n;
109     next->grstart = com->rstart + next->rstart;
110     ierr = PetscMalloc(size*sizeof(PetscInt),&next->grstarts);CHKERRQ(ierr);
111     ierr = MPI_Allgather(&next->grstart,1,MPIU_INT,next->grstarts,1,MPIU_INT,((PetscObject)dm)->comm);CHKERRQ(ierr);
112     next = next->next;
113   }
114   com->setup = PETSC_TRUE;
115   PetscFunctionReturn(0);
116 }
117 
118 /* ----------------------------------------------------------------------------------*/
119 
120 #include <stdarg.h>
121 
122 #undef __FUNCT__
123 #define __FUNCT__ "DMCompositeGetNumberDM"
124 /*@C
125     DMCompositeGetNumberDM - Get's the number of DM objects in the DMComposite
126        representation.
127 
128     Not Collective
129 
130     Input Parameter:
131 .    dm - the packer object
132 
133     Output Parameter:
134 .     nDM - the number of DMs
135 
136     Level: beginner
137 
138 @*/
139 PetscErrorCode  DMCompositeGetNumberDM(DM dm,PetscInt *nDM)
140 {
141   DM_Composite *com = (DM_Composite*)dm->data;
142   PetscFunctionBegin;
143   PetscValidHeaderSpecific(dm,DM_CLASSID,1);
144   *nDM = com->nDM;
145   PetscFunctionReturn(0);
146 }
147 
148 
149 #undef __FUNCT__
150 #define __FUNCT__ "DMCompositeGetAccess"
151 /*@C
152     DMCompositeGetAccess - Allows one to access the individual packed vectors in their global
153        representation.
154 
155     Collective on DMComposite
156 
157     Input Parameters:
158 +    dm - the packer object
159 -    gvec - the global vector
160 
161     Output Parameters:
162 .    Vec* ... - the packed parallel vectors, PETSC_NULL for those that are not needed
163 
164     Notes: Use DMCompositeRestoreAccess() to return the vectors when you no longer need them
165 
166     Level: advanced
167 
168 @*/
169 PetscErrorCode  DMCompositeGetAccess(DM dm,Vec gvec,...)
170 {
171   va_list                Argp;
172   PetscErrorCode         ierr;
173   struct DMCompositeLink *next;
174   DM_Composite           *com = (DM_Composite*)dm->data;
175 
176   PetscFunctionBegin;
177   PetscValidHeaderSpecific(dm,DM_CLASSID,1);
178   PetscValidHeaderSpecific(gvec,VEC_CLASSID,2);
179   next = com->next;
180   if (!com->setup) {
181     ierr = DMSetUp(dm);CHKERRQ(ierr);
182   }
183 
184   /* loop over packed objects, handling one at at time */
185   va_start(Argp,gvec);
186   while (next) {
187     Vec *vec;
188     vec = va_arg(Argp, Vec*);
189     if (vec) {
190       PetscScalar *array;
191       ierr = DMGetGlobalVector(next->dm,vec);CHKERRQ(ierr);
192       ierr = VecGetArray(gvec,&array);CHKERRQ(ierr);
193       ierr = VecPlaceArray(*vec,array+next->rstart);CHKERRQ(ierr);
194       ierr = VecRestoreArray(gvec,&array);CHKERRQ(ierr);
195     }
196     next = next->next;
197   }
198   va_end(Argp);
199   PetscFunctionReturn(0);
200 }
201 
202 #undef __FUNCT__
203 #define __FUNCT__ "DMCompositeRestoreAccess"
204 /*@C
205     DMCompositeRestoreAccess - Returns the vectors obtained with DMCompositeGetAccess()
206        representation.
207 
208     Collective on DMComposite
209 
210     Input Parameters:
211 +    dm - the packer object
212 .    gvec - the global vector
213 -    Vec* ... - the individual parallel vectors, PETSC_NULL for those that are not needed
214 
215     Level: advanced
216 
217 .seealso  DMCompositeAddDM(), DMCreateGlobalVector(),
218          DMCompositeGather(), DMCompositeCreate(), DMCompositeGetISLocalToGlobalMappings(), DMCompositeScatter(),
219          DMCompositeRestoreAccess(), DMCompositeGetAccess()
220 
221 @*/
222 PetscErrorCode  DMCompositeRestoreAccess(DM dm,Vec gvec,...)
223 {
224   va_list                Argp;
225   PetscErrorCode         ierr;
226   struct DMCompositeLink *next;
227   DM_Composite           *com = (DM_Composite*)dm->data;
228 
229   PetscFunctionBegin;
230   PetscValidHeaderSpecific(dm,DM_CLASSID,1);
231   PetscValidHeaderSpecific(gvec,VEC_CLASSID,2);
232   next = com->next;
233   if (!com->setup) {
234     ierr = DMSetUp(dm);CHKERRQ(ierr);
235   }
236 
237   /* loop over packed objects, handling one at at time */
238   va_start(Argp,gvec);
239   while (next) {
240     Vec *vec;
241     vec = va_arg(Argp, Vec*);
242     if (vec) {
243       ierr = VecResetArray(*vec);CHKERRQ(ierr);
244       ierr = DMRestoreGlobalVector(next->dm,vec);CHKERRQ(ierr);
245     }
246     next = next->next;
247   }
248   va_end(Argp);
249   PetscFunctionReturn(0);
250 }
251 
252 #undef __FUNCT__
253 #define __FUNCT__ "DMCompositeScatter"
254 /*@C
255     DMCompositeScatter - Scatters from a global packed vector into its individual local vectors
256 
257     Collective on DMComposite
258 
259     Input Parameters:
260 +    dm - the packer object
261 .    gvec - the global vector
262 -    Vec ... - the individual sequential vectors, PETSC_NULL for those that are not needed
263 
264     Level: advanced
265 
266 .seealso DMDestroy(), DMCompositeAddDM(), DMCreateGlobalVector(),
267          DMCompositeGather(), DMCompositeCreate(), DMCompositeGetISLocalToGlobalMappings(), DMCompositeGetAccess(),
268          DMCompositeGetLocalVectors(), DMCompositeRestoreLocalVectors(), DMCompositeGetEntries()
269 
270 @*/
271 PetscErrorCode  DMCompositeScatter(DM dm,Vec gvec,...)
272 {
273   va_list                Argp;
274   PetscErrorCode         ierr;
275   struct DMCompositeLink *next;
276   PetscInt               cnt;
277   DM_Composite           *com = (DM_Composite*)dm->data;
278 
279   PetscFunctionBegin;
280   PetscValidHeaderSpecific(dm,DM_CLASSID,1);
281   PetscValidHeaderSpecific(gvec,VEC_CLASSID,2);
282   if (!com->setup) {
283     ierr = DMSetUp(dm);CHKERRQ(ierr);
284   }
285 
286   /* loop over packed objects, handling one at at time */
287   va_start(Argp,gvec);
288   for (cnt=3,next=com->next; next; cnt++,next=next->next) {
289     Vec local;
290     local = va_arg(Argp, Vec);
291     if (local) {
292       Vec global;
293       PetscScalar *array;
294       PetscValidHeaderSpecific(local,VEC_CLASSID,cnt);
295       ierr = DMGetGlobalVector(next->dm,&global);CHKERRQ(ierr);
296       ierr = VecGetArray(gvec,&array);CHKERRQ(ierr);
297       ierr = VecPlaceArray(global,array+next->rstart);CHKERRQ(ierr);
298       ierr = DMGlobalToLocalBegin(next->dm,global,INSERT_VALUES,local);CHKERRQ(ierr);
299       ierr = DMGlobalToLocalEnd(next->dm,global,INSERT_VALUES,local);CHKERRQ(ierr);
300       ierr = VecRestoreArray(gvec,&array);CHKERRQ(ierr);
301       ierr = VecResetArray(global);CHKERRQ(ierr);
302       ierr = DMRestoreGlobalVector(next->dm,&global);CHKERRQ(ierr);
303     }
304   }
305   va_end(Argp);
306   PetscFunctionReturn(0);
307 }
308 
309 #undef __FUNCT__
310 #define __FUNCT__ "DMCompositeGather"
311 /*@C
312     DMCompositeGather - Gathers into a global packed vector from its individual local vectors
313 
314     Collective on DMComposite
315 
316     Input Parameter:
317 +    dm - the packer object
318 .    gvec - the global vector
319 -    Vec ... - the individual sequential vectors, PETSC_NULL for any that are not needed
320 
321     Level: advanced
322 
323 .seealso DMDestroy(), DMCompositeAddDM(), DMCreateGlobalVector(),
324          DMCompositeScatter(), DMCompositeCreate(), DMCompositeGetISLocalToGlobalMappings(), DMCompositeGetAccess(),
325          DMCompositeGetLocalVectors(), DMCompositeRestoreLocalVectors(), DMCompositeGetEntries()
326 
327 @*/
328 PetscErrorCode  DMCompositeGather(DM dm,Vec gvec,InsertMode imode,...)
329 {
330   va_list                Argp;
331   PetscErrorCode         ierr;
332   struct DMCompositeLink *next;
333   DM_Composite           *com = (DM_Composite*)dm->data;
334   PetscInt               cnt;
335 
336   PetscFunctionBegin;
337   PetscValidHeaderSpecific(dm,DM_CLASSID,1);
338   PetscValidHeaderSpecific(gvec,VEC_CLASSID,2);
339   if (!com->setup) {
340     ierr = DMSetUp(dm);CHKERRQ(ierr);
341   }
342 
343   /* loop over packed objects, handling one at at time */
344   va_start(Argp,imode);
345   for (cnt=3,next=com->next; next; cnt++,next=next->next) {
346     Vec local;
347     local = va_arg(Argp, Vec);
348     if (local) {
349       PetscScalar    *array;
350       Vec            global;
351       PetscValidHeaderSpecific(local,VEC_CLASSID,cnt);
352       ierr = DMGetGlobalVector(next->dm,&global);CHKERRQ(ierr);
353       ierr = VecGetArray(gvec,&array);CHKERRQ(ierr);
354       ierr = VecPlaceArray(global,array+next->rstart);CHKERRQ(ierr);
355       ierr = DMLocalToGlobalBegin(next->dm,local,imode,global);CHKERRQ(ierr);
356       ierr = DMLocalToGlobalEnd(next->dm,local,imode,global);CHKERRQ(ierr);
357       ierr = VecRestoreArray(gvec,&array);CHKERRQ(ierr);
358       ierr = VecResetArray(global);CHKERRQ(ierr);
359       ierr = DMRestoreGlobalVector(next->dm,&global);CHKERRQ(ierr);
360     }
361   }
362   va_end(Argp);
363   PetscFunctionReturn(0);
364 }
365 
366 #undef __FUNCT__
367 #define __FUNCT__ "DMCompositeAddDM"
368 /*@C
369     DMCompositeAddDM - adds a DM  vector to a DMComposite
370 
371     Collective on DMComposite
372 
373     Input Parameter:
374 +    dm - the packer object
375 -    dm - the DM object, if the DM is a da you will need to caste it with a (DM)
376 
377     Level: advanced
378 
379 .seealso DMDestroy(), DMCompositeGather(), DMCompositeAddDM(), DMCreateGlobalVector(),
380          DMCompositeScatter(), DMCompositeCreate(), DMCompositeGetISLocalToGlobalMappings(), DMCompositeGetAccess(),
381          DMCompositeGetLocalVectors(), DMCompositeRestoreLocalVectors(), DMCompositeGetEntries()
382 
383 @*/
384 PetscErrorCode  DMCompositeAddDM(DM dmc,DM dm)
385 {
386   PetscErrorCode         ierr;
387   PetscInt               n,nlocal;
388   struct DMCompositeLink *mine,*next;
389   Vec                    global,local;
390   DM_Composite           *com = (DM_Composite*)dmc->data;
391 
392   PetscFunctionBegin;
393   PetscValidHeaderSpecific(dmc,DM_CLASSID,1);
394   PetscValidHeaderSpecific(dm,DM_CLASSID,2);
395   next = com->next;
396   if (com->setup) SETERRQ(((PetscObject)dmc)->comm,PETSC_ERR_ARG_WRONGSTATE,"Cannot add a DM once you have used the DMComposite");
397 
398   /* create new link */
399   ierr = PetscNew(struct DMCompositeLink,&mine);CHKERRQ(ierr);
400   ierr = PetscObjectReference((PetscObject)dm);CHKERRQ(ierr);
401   ierr = DMGetGlobalVector(dm,&global);CHKERRQ(ierr);
402   ierr = VecGetLocalSize(global,&n);CHKERRQ(ierr);
403   ierr = DMRestoreGlobalVector(dm,&global);CHKERRQ(ierr);
404   ierr = DMGetLocalVector(dm,&local);CHKERRQ(ierr);
405   ierr = VecGetSize(local,&nlocal);CHKERRQ(ierr);
406   ierr = DMRestoreLocalVector(dm,&local);CHKERRQ(ierr);
407   mine->n      = n;
408   mine->nlocal = nlocal;
409   mine->dm     = dm;
410   mine->next   = PETSC_NULL;
411   com->n       += n;
412 
413   /* add to end of list */
414   if (!next) {
415     com->next = mine;
416   } else {
417     while (next->next) next = next->next;
418     next->next = mine;
419   }
420   com->nDM++;
421   com->nmine++;
422   PetscFunctionReturn(0);
423 }
424 
425 extern PetscErrorCode  VecView_MPI(Vec,PetscViewer);
426 EXTERN_C_BEGIN
427 #undef __FUNCT__
428 #define __FUNCT__ "VecView_DMComposite"
429 PetscErrorCode  VecView_DMComposite(Vec gvec,PetscViewer viewer)
430 {
431   DM                     dm;
432   PetscErrorCode         ierr;
433   struct DMCompositeLink *next;
434   PetscBool              isdraw;
435   DM_Composite           *com;
436 
437   PetscFunctionBegin;
438   ierr = PetscObjectQuery((PetscObject)gvec,"DM",(PetscObject*)&dm);CHKERRQ(ierr);
439   if (!dm) SETERRQ(((PetscObject)gvec)->comm,PETSC_ERR_ARG_WRONG,"Vector not generated from a DMComposite");
440   com = (DM_Composite*)dm->data;
441   next = com->next;
442 
443   ierr = PetscTypeCompare((PetscObject)viewer,PETSCVIEWERDRAW,&isdraw);CHKERRQ(ierr);
444   if (!isdraw) {
445     /* do I really want to call this? */
446     ierr = VecView_MPI(gvec,viewer);CHKERRQ(ierr);
447   } else {
448     PetscInt cnt = 0;
449 
450     /* loop over packed objects, handling one at at time */
451     while (next) {
452       Vec         vec;
453       PetscScalar *array;
454       PetscInt    bs;
455 
456       /* Should use VecGetSubVector() eventually, but would need to forward the DM for that to work */
457       ierr = DMGetGlobalVector(next->dm,&vec);CHKERRQ(ierr);
458       ierr = VecGetArray(gvec,&array);CHKERRQ(ierr);
459       ierr = VecPlaceArray(vec,array+next->rstart);CHKERRQ(ierr);
460       ierr = VecRestoreArray(gvec,&array);CHKERRQ(ierr);
461       ierr = VecView(vec,viewer);CHKERRQ(ierr);
462       ierr = VecGetBlockSize(vec,&bs);CHKERRQ(ierr);
463       ierr = VecResetArray(vec);CHKERRQ(ierr);
464       ierr = DMRestoreGlobalVector(next->dm,&vec);CHKERRQ(ierr);
465       ierr = PetscViewerDrawBaseAdd(viewer,bs);CHKERRQ(ierr);
466       cnt += bs;
467       next = next->next;
468     }
469     ierr = PetscViewerDrawBaseAdd(viewer,-cnt);CHKERRQ(ierr);
470   }
471   PetscFunctionReturn(0);
472 }
473 EXTERN_C_END
474 
475 
476 #undef __FUNCT__
477 #define __FUNCT__ "DMCreateGlobalVector_Composite"
478 PetscErrorCode  DMCreateGlobalVector_Composite(DM dm,Vec *gvec)
479 {
480   PetscErrorCode         ierr;
481   DM_Composite           *com = (DM_Composite*)dm->data;
482 
483   PetscFunctionBegin;
484   PetscValidHeaderSpecific(dm,DM_CLASSID,1);
485   if (!com->setup) {
486     ierr = DMSetUp(dm);CHKERRQ(ierr);
487   }
488   ierr = VecCreateMPI(((PetscObject)dm)->comm,com->n,com->N,gvec);CHKERRQ(ierr);
489   ierr = PetscObjectCompose((PetscObject)*gvec,"DM",(PetscObject)dm);CHKERRQ(ierr);
490   ierr = VecSetOperation(*gvec,VECOP_VIEW,(void(*)(void))VecView_DMComposite);CHKERRQ(ierr);
491   PetscFunctionReturn(0);
492 }
493 
494 #undef __FUNCT__
495 #define __FUNCT__ "DMCreateLocalVector_Composite"
496 PetscErrorCode  DMCreateLocalVector_Composite(DM dm,Vec *lvec)
497 {
498   PetscErrorCode         ierr;
499   DM_Composite           *com = (DM_Composite*)dm->data;
500 
501   PetscFunctionBegin;
502   PetscValidHeaderSpecific(dm,DM_CLASSID,1);
503   if (!com->setup) {
504     ierr = DMSetUp(dm);CHKERRQ(ierr);
505   }
506   ierr = VecCreateSeq(((PetscObject)dm)->comm,com->nghost,lvec);CHKERRQ(ierr);
507   ierr = PetscObjectCompose((PetscObject)*lvec,"DM",(PetscObject)dm);CHKERRQ(ierr);
508   PetscFunctionReturn(0);
509 }
510 
511 #undef __FUNCT__
512 #define __FUNCT__ "DMCompositeGetISLocalToGlobalMappings"
513 /*@C
514     DMCompositeGetISLocalToGlobalMappings - gets an ISLocalToGlobalMapping for each DM in the DMComposite, maps to the composite global space
515 
516     Collective on DM
517 
518     Input Parameter:
519 .    dm - the packer object
520 
521     Output Parameters:
522 .    ltogs - the individual mappings for each packed vector. Note that this includes
523            all the ghost points that individual ghosted DMDA's may have.
524 
525     Level: advanced
526 
527     Notes:
528        Each entry of ltogs should be destroyed with ISLocalToGlobalMappingDestroy(), the ltogs array should be freed with PetscFree().
529 
530 .seealso DMDestroy(), DMCompositeAddDM(), DMCreateGlobalVector(),
531          DMCompositeGather(), DMCompositeCreate(), DMCompositeGetAccess(), DMCompositeScatter(),
532          DMCompositeGetLocalVectors(), DMCompositeRestoreLocalVectors(),DMCompositeGetEntries()
533 
534 @*/
535 PetscErrorCode  DMCompositeGetISLocalToGlobalMappings(DM dm,ISLocalToGlobalMapping **ltogs)
536 {
537   PetscErrorCode         ierr;
538   PetscInt               i,*idx,n,cnt;
539   struct DMCompositeLink *next;
540   PetscMPIInt            rank;
541   DM_Composite           *com = (DM_Composite*)dm->data;
542 
543   PetscFunctionBegin;
544   PetscValidHeaderSpecific(dm,DM_CLASSID,1);
545   ierr = PetscMalloc((com->nDM)*sizeof(ISLocalToGlobalMapping),ltogs);CHKERRQ(ierr);
546   next = com->next;
547   ierr = MPI_Comm_rank(((PetscObject)dm)->comm,&rank);CHKERRQ(ierr);
548 
549   /* loop over packed objects, handling one at at time */
550   cnt = 0;
551   while (next) {
552     ISLocalToGlobalMapping ltog;
553     PetscMPIInt            size;
554     const PetscInt         *suboff,*indices;
555     Vec                    global;
556 
557     /* Get sub-DM global indices for each local dof */
558     ierr = DMGetLocalToGlobalMapping(next->dm,&ltog);CHKERRQ(ierr);
559     ierr = ISLocalToGlobalMappingGetSize(ltog,&n);CHKERRQ(ierr);
560     ierr = ISLocalToGlobalMappingGetIndices(ltog,&indices);CHKERRQ(ierr);
561     ierr = PetscMalloc(n*sizeof(PetscInt),&idx);CHKERRQ(ierr);
562 
563     /* Get the offsets for the sub-DM global vector */
564     ierr = DMGetGlobalVector(next->dm,&global);CHKERRQ(ierr);
565     ierr = VecGetOwnershipRanges(global,&suboff);CHKERRQ(ierr);
566     ierr = MPI_Comm_size(((PetscObject)global)->comm,&size);CHKERRQ(ierr);
567 
568     /* Shift the sub-DM definition of the global space to the composite global space */
569     for (i=0; i<n; i++) {
570       PetscInt subi = indices[i],lo = 0,hi = size,t;
571       /* Binary search to find which rank owns subi */
572       while (hi-lo > 1) {
573         t = lo + (hi-lo)/2;
574         if (suboff[t] > subi) hi = t;
575         else                  lo = t;
576       }
577       idx[i] = subi - suboff[lo] + next->grstarts[lo];
578     }
579     ierr = ISLocalToGlobalMappingRestoreIndices(ltog,&indices);CHKERRQ(ierr);
580     ierr = ISLocalToGlobalMappingCreate(((PetscObject)dm)->comm,n,idx,PETSC_OWN_POINTER,&(*ltogs)[cnt]);CHKERRQ(ierr);
581     ierr = DMRestoreGlobalVector(next->dm,&global);CHKERRQ(ierr);
582     next = next->next;
583     cnt++;
584   }
585   PetscFunctionReturn(0);
586 }
587 
588 #undef __FUNCT__
589 #define __FUNCT__ "DMCompositeGetLocalISs"
590 /*@C
591    DMCompositeGetLocalISs - Gets index sets for each component of a composite local vector
592 
593    Not Collective
594 
595    Input Arguments:
596 . dm - composite DM
597 
598    Output Arguments:
599 . is - array of serial index sets for each each component of the DMComposite
600 
601    Level: intermediate
602 
603    Notes:
604    At present, a composite local vector does not normally exist.  This function is used to provide index sets for
605    MatGetLocalSubMatrix().  In the future, the scatters for each entry in the DMComposite may be be merged into a single
606    scatter to a composite local vector.  The user should not typically need to know which is being done.
607 
608    To get the composite global indices at all local points (including ghosts), use DMCompositeGetISLocalToGlobalMappings().
609 
610    To get index sets for pieces of the composite global vector, use DMCompositeGetGlobalISs().
611 
612    Each returned IS should be destroyed with ISDestroy(), the array should be freed with PetscFree().
613 
614 .seealso: DMCompositeGetGlobalISs(), DMCompositeGetISLocalToGlobalMappings(), MatGetLocalSubMatrix(), MatCreateLocalRef()
615 @*/
616 PetscErrorCode  DMCompositeGetLocalISs(DM dm,IS **is)
617 {
618   PetscErrorCode         ierr;
619   DM_Composite           *com = (DM_Composite*)dm->data;
620   struct DMCompositeLink *link;
621   PetscInt cnt,start;
622 
623   PetscFunctionBegin;
624   PetscValidHeaderSpecific(dm,DM_CLASSID,1);
625   PetscValidPointer(is,2);
626   ierr = PetscMalloc(com->nmine*sizeof(IS),is);CHKERRQ(ierr);
627   for (cnt=0,start=0,link=com->next; link; start+=link->nlocal,cnt++,link=link->next) {
628     PetscInt bs;
629     ierr = ISCreateStride(PETSC_COMM_SELF,link->nlocal,start,1,&(*is)[cnt]);CHKERRQ(ierr);
630     ierr = DMGetBlockSize(link->dm,&bs);CHKERRQ(ierr);
631     ierr = ISSetBlockSize((*is)[cnt],bs);CHKERRQ(ierr);
632   }
633   PetscFunctionReturn(0);
634 }
635 
636 #undef __FUNCT__
637 #define __FUNCT__ "DMCompositeGetGlobalISs"
638 /*@C
639     DMCompositeGetGlobalISs - Gets the index sets for each composed object
640 
641     Collective on DMComposite
642 
643     Input Parameter:
644 .    dm - the packer object
645 
646     Output Parameters:
647 .    is - the array of index sets
648 
649     Level: advanced
650 
651     Notes:
652        The is entries should be destroyed with ISDestroy(), the is array should be freed with PetscFree()
653 
654        These could be used to extract a subset of vector entries for a "multi-physics" preconditioner
655 
656        Use DMCompositeGetLocalISs() for index sets in the packed local numbering, and
657        DMCompositeGetISLocalToGlobalMappings() for to map local sub-DM (including ghost) indices to packed global
658        indices.
659 
660 .seealso DMDestroy(), DMCompositeAddDM(), DMCreateGlobalVector(),
661          DMCompositeGather(), DMCompositeCreate(), DMCompositeGetAccess(), DMCompositeScatter(),
662          DMCompositeGetLocalVectors(), DMCompositeRestoreLocalVectors(),DMCompositeGetEntries()
663 
664 @*/
665 
666 PetscErrorCode  DMCompositeGetGlobalISs(DM dm,IS *is[])
667 {
668   PetscErrorCode         ierr;
669   PetscInt               cnt = 0,*idx,i;
670   struct DMCompositeLink *next;
671   PetscMPIInt            rank;
672   DM_Composite           *com = (DM_Composite*)dm->data;
673 
674   PetscFunctionBegin;
675   PetscValidHeaderSpecific(dm,DM_CLASSID,1);
676   ierr = PetscMalloc((com->nDM)*sizeof(IS),is);CHKERRQ(ierr);
677   next = com->next;
678   ierr = MPI_Comm_rank(((PetscObject)dm)->comm,&rank);CHKERRQ(ierr);
679 
680   /* loop over packed objects, handling one at at time */
681   while (next) {
682     ierr = PetscMalloc(next->n*sizeof(PetscInt),&idx);CHKERRQ(ierr);
683     for (i=0; i<next->n; i++) idx[i] = next->grstart + i;
684     ierr = ISCreateGeneral(((PetscObject)dm)->comm,next->n,idx,PETSC_OWN_POINTER,&(*is)[cnt]);CHKERRQ(ierr);
685     cnt++;
686     next = next->next;
687   }
688   PetscFunctionReturn(0);
689 }
690 
691 /* -------------------------------------------------------------------------------------*/
692 #undef __FUNCT__
693 #define __FUNCT__ "DMCompositeGetLocalVectors"
694 /*@C
695     DMCompositeGetLocalVectors - Gets local vectors for each part of a DMComposite.
696        Use DMCompositeRestoreLocalVectors() to return them.
697 
698     Not Collective
699 
700     Input Parameter:
701 .    dm - the packer object
702 
703     Output Parameter:
704 .   Vec ... - the individual sequential Vecs
705 
706     Level: advanced
707 
708 .seealso DMDestroy(), DMCompositeAddDM(), DMCreateGlobalVector(),
709          DMCompositeGather(), DMCompositeCreate(), DMCompositeGetISLocalToGlobalMappings(), DMCompositeGetAccess(),
710          DMCompositeRestoreLocalVectors(), DMCompositeScatter(), DMCompositeGetEntries()
711 
712 @*/
713 PetscErrorCode  DMCompositeGetLocalVectors(DM dm,...)
714 {
715   va_list                Argp;
716   PetscErrorCode         ierr;
717   struct DMCompositeLink *next;
718   DM_Composite           *com = (DM_Composite*)dm->data;
719 
720   PetscFunctionBegin;
721   PetscValidHeaderSpecific(dm,DM_CLASSID,1);
722   next = com->next;
723   /* loop over packed objects, handling one at at time */
724   va_start(Argp,dm);
725   while (next) {
726     Vec *vec;
727     vec = va_arg(Argp, Vec*);
728     ierr = DMGetLocalVector(next->dm,vec);CHKERRQ(ierr);
729     next = next->next;
730   }
731   va_end(Argp);
732   PetscFunctionReturn(0);
733 }
734 
735 #undef __FUNCT__
736 #define __FUNCT__ "DMCompositeRestoreLocalVectors"
737 /*@C
738     DMCompositeRestoreLocalVectors - Restores local vectors for each part of a DMComposite.
739 
740     Not Collective
741 
742     Input Parameter:
743 .    dm - the packer object
744 
745     Output Parameter:
746 .   Vec ... - the individual sequential Vecs
747 
748     Level: advanced
749 
750 .seealso DMDestroy(), DMCompositeAddDM(), DMCreateGlobalVector(),
751          DMCompositeGather(), DMCompositeCreate(), DMCompositeGetISLocalToGlobalMappings(), DMCompositeGetAccess(),
752          DMCompositeGetLocalVectors(), DMCompositeScatter(), DMCompositeGetEntries()
753 
754 @*/
755 PetscErrorCode  DMCompositeRestoreLocalVectors(DM dm,...)
756 {
757   va_list                Argp;
758   PetscErrorCode         ierr;
759   struct DMCompositeLink *next;
760   DM_Composite           *com = (DM_Composite*)dm->data;
761 
762   PetscFunctionBegin;
763   PetscValidHeaderSpecific(dm,DM_CLASSID,1);
764   next = com->next;
765   /* loop over packed objects, handling one at at time */
766   va_start(Argp,dm);
767   while (next) {
768     Vec *vec;
769     vec = va_arg(Argp, Vec*);
770     ierr = DMRestoreLocalVector(next->dm,vec);CHKERRQ(ierr);
771     next = next->next;
772   }
773   va_end(Argp);
774   PetscFunctionReturn(0);
775 }
776 
777 /* -------------------------------------------------------------------------------------*/
778 #undef __FUNCT__
779 #define __FUNCT__ "DMCompositeGetEntries"
780 /*@C
781     DMCompositeGetEntries - Gets the DM for each entry in a DMComposite.
782 
783     Not Collective
784 
785     Input Parameter:
786 .    dm - the packer object
787 
788     Output Parameter:
789 .   DM ... - the individual entries (DMs)
790 
791     Level: advanced
792 
793 .seealso DMDestroy(), DMCompositeAddDM(), DMCreateGlobalVector(),
794          DMCompositeGather(), DMCompositeCreate(), DMCompositeGetISLocalToGlobalMappings(), DMCompositeGetAccess(),
795          DMCompositeRestoreLocalVectors(), DMCompositeGetLocalVectors(),  DMCompositeScatter(),
796          DMCompositeGetLocalVectors(), DMCompositeRestoreLocalVectors()
797 
798 @*/
799 PetscErrorCode  DMCompositeGetEntries(DM dm,...)
800 {
801   va_list                Argp;
802   struct DMCompositeLink *next;
803   DM_Composite           *com = (DM_Composite*)dm->data;
804 
805   PetscFunctionBegin;
806   PetscValidHeaderSpecific(dm,DM_CLASSID,1);
807   next = com->next;
808   /* loop over packed objects, handling one at at time */
809   va_start(Argp,dm);
810   while (next) {
811     DM *dmn;
812     dmn = va_arg(Argp, DM*);
813     if (dmn) *dmn = next->dm;
814     next = next->next;
815   }
816   va_end(Argp);
817   PetscFunctionReturn(0);
818 }
819 
820 #undef __FUNCT__
821 #define __FUNCT__ "DMRefine_Composite"
822 PetscErrorCode  DMRefine_Composite(DM dmi,MPI_Comm comm,DM *fine)
823 {
824   PetscErrorCode         ierr;
825   struct DMCompositeLink *next;
826   DM_Composite           *com = (DM_Composite*)dmi->data;
827   DM                     dm;
828 
829   PetscFunctionBegin;
830   PetscValidHeaderSpecific(dmi,DM_CLASSID,1);
831   next = com->next;
832   ierr = DMCompositeCreate(comm,fine);CHKERRQ(ierr);
833 
834   /* loop over packed objects, handling one at at time */
835   while (next) {
836     ierr = DMRefine(next->dm,comm,&dm);CHKERRQ(ierr);
837     ierr = DMCompositeAddDM(*fine,dm);CHKERRQ(ierr);
838     ierr = PetscObjectDereference((PetscObject)dm);CHKERRQ(ierr);
839     next = next->next;
840   }
841   PetscFunctionReturn(0);
842 }
843 
844 #undef __FUNCT__
845 #define __FUNCT__ "DMCoarsen_Composite"
846 PetscErrorCode  DMCoarsen_Composite(DM dmi,MPI_Comm comm,DM *fine)
847 {
848   PetscErrorCode         ierr;
849   struct DMCompositeLink *next;
850   DM_Composite           *com = (DM_Composite*)dmi->data;
851   DM                     dm;
852 
853   PetscFunctionBegin;
854   PetscValidHeaderSpecific(dmi,DM_CLASSID,1);
855   next = com->next;
856   ierr = DMCompositeCreate(comm,fine);CHKERRQ(ierr);
857 
858   /* loop over packed objects, handling one at at time */
859   while (next) {
860     ierr = DMCoarsen(next->dm,comm,&dm);CHKERRQ(ierr);
861     ierr = DMCompositeAddDM(*fine,dm);CHKERRQ(ierr);
862     ierr = PetscObjectDereference((PetscObject)dm);CHKERRQ(ierr);
863     next = next->next;
864   }
865   PetscFunctionReturn(0);
866 }
867 
868 #undef __FUNCT__
869 #define __FUNCT__ "DMGetInterpolation_Composite"
870 PetscErrorCode  DMGetInterpolation_Composite(DM coarse,DM fine,Mat *A,Vec *v)
871 {
872   PetscErrorCode         ierr;
873   PetscInt               m,n,M,N,nDM,i;
874   struct DMCompositeLink *nextc;
875   struct DMCompositeLink *nextf;
876   Vec                    gcoarse,gfine;
877   DM_Composite           *comcoarse = (DM_Composite*)coarse->data;
878   DM_Composite           *comfine = (DM_Composite*)fine->data;
879   Mat                    *mats;
880 
881   PetscFunctionBegin;
882   PetscValidHeaderSpecific(coarse,DM_CLASSID,1);
883   PetscValidHeaderSpecific(fine,DM_CLASSID,2);
884   /* use global vectors only for determining matrix layout */
885   ierr = DMGetGlobalVector(coarse,&gcoarse);CHKERRQ(ierr);
886   ierr = DMGetGlobalVector(fine,&gfine);CHKERRQ(ierr);
887   ierr = VecGetLocalSize(gcoarse,&n);CHKERRQ(ierr);
888   ierr = VecGetLocalSize(gfine,&m);CHKERRQ(ierr);
889   ierr = VecGetSize(gcoarse,&N);CHKERRQ(ierr);
890   ierr = VecGetSize(gfine,&M);CHKERRQ(ierr);
891   ierr = DMRestoreGlobalVector(coarse,&gcoarse);CHKERRQ(ierr);
892   ierr = DMRestoreGlobalVector(fine,&gfine);CHKERRQ(ierr);
893 
894   nDM = comfine->nDM;
895   if (nDM != comcoarse->nDM) SETERRQ2(((PetscObject)fine)->comm,PETSC_ERR_ARG_INCOMP,"Fine DMComposite has %D entries, but coarse has %D",nDM,comcoarse->nDM);
896   ierr = PetscMalloc(nDM*nDM*sizeof(Mat),&mats);CHKERRQ(ierr);
897   ierr = PetscMemzero(mats,nDM*nDM*sizeof(Mat));CHKERRQ(ierr);
898 
899   /* loop over packed objects, handling one at at time */
900   for (nextc=comcoarse->next,nextf=comfine->next,i=0; nextc; nextc=nextc->next,nextf=nextf->next,i++) {
901     ierr = DMGetInterpolation(nextc->dm,nextf->dm,&mats[i*nDM+i],PETSC_NULL);CHKERRQ(ierr);
902   }
903   ierr = MatCreateNest(((PetscObject)fine)->comm,nDM,PETSC_NULL,nDM,PETSC_NULL,mats,A);CHKERRQ(ierr);
904   for (i=0; i<nDM*nDM; i++) {ierr = MatDestroy(&mats[i]);CHKERRQ(ierr);}
905   ierr = PetscFree(mats);CHKERRQ(ierr);
906   PetscFunctionReturn(0);
907 }
908 
909 #undef __FUNCT__
910 #define __FUNCT__ "DMCreateLocalToGlobalMapping_Composite"
911 static PetscErrorCode DMCreateLocalToGlobalMapping_Composite(DM dm)
912 {
913   DM_Composite           *com = (DM_Composite*)dm->data;
914   ISLocalToGlobalMapping *ltogs;
915   PetscInt               i;
916   PetscErrorCode         ierr;
917 
918   PetscFunctionBegin;
919   /* Set the ISLocalToGlobalMapping on the new matrix */
920   ierr = DMCompositeGetISLocalToGlobalMappings(dm,&ltogs);CHKERRQ(ierr);
921   ierr = ISLocalToGlobalMappingConcatenate(((PetscObject)dm)->comm,com->nDM,ltogs,&dm->ltogmap);CHKERRQ(ierr);
922   for (i=0; i<com->nDM; i++) {ierr = ISLocalToGlobalMappingDestroy(&ltogs[i]);CHKERRQ(ierr);}
923   ierr = PetscFree(ltogs);CHKERRQ(ierr);
924   PetscFunctionReturn(0);
925 }
926 
927 
928 #undef __FUNCT__
929 #define __FUNCT__ "DMGetColoring_Composite"
930 PetscErrorCode  DMGetColoring_Composite(DM dm,ISColoringType ctype,const MatType mtype,ISColoring *coloring)
931 {
932   PetscErrorCode         ierr;
933   PetscInt               n,i,cnt;
934   ISColoringValue        *colors;
935   PetscBool              dense = PETSC_FALSE;
936   ISColoringValue        maxcol = 0;
937   DM_Composite           *com = (DM_Composite*)dm->data;
938 
939   PetscFunctionBegin;
940   PetscValidHeaderSpecific(dm,DM_CLASSID,1);
941   if (ctype == IS_COLORING_GHOSTED) {
942     SETERRQ(((PetscObject)dm)->comm,PETSC_ERR_SUP,"Currently you must use -dmmg_iscoloring_type global" );
943   } else if (ctype == IS_COLORING_GLOBAL) {
944     n = com->n;
945   } else SETERRQ(((PetscObject)dm)->comm,PETSC_ERR_ARG_OUTOFRANGE,"Unknown ISColoringType");
946   ierr = PetscMalloc(n*sizeof(ISColoringValue),&colors);CHKERRQ(ierr); /* freed in ISColoringDestroy() */
947 
948   ierr = PetscOptionsGetBool(PETSC_NULL,"-dmcomposite_dense_jacobian",&dense,PETSC_NULL);CHKERRQ(ierr);
949   if (dense) {
950     for (i=0; i<n; i++) {
951       colors[i] = (ISColoringValue)(com->rstart + i);
952     }
953     maxcol = com->N;
954   } else {
955     struct DMCompositeLink *next = com->next;
956     PetscMPIInt            rank;
957 
958     ierr = MPI_Comm_rank(((PetscObject)dm)->comm,&rank);CHKERRQ(ierr);
959     cnt  = 0;
960     while (next) {
961       ISColoring     lcoloring;
962 
963       ierr = DMGetColoring(next->dm,IS_COLORING_GLOBAL,mtype,&lcoloring);CHKERRQ(ierr);
964       for (i=0; i<lcoloring->N; i++) {
965         colors[cnt++] = maxcol + lcoloring->colors[i];
966       }
967       maxcol += lcoloring->n;
968       ierr = ISColoringDestroy(&lcoloring);CHKERRQ(ierr);
969       next = next->next;
970     }
971   }
972   ierr = ISColoringCreate(((PetscObject)dm)->comm,maxcol,n,colors,coloring);CHKERRQ(ierr);
973   PetscFunctionReturn(0);
974 }
975 
976 #undef __FUNCT__
977 #define __FUNCT__ "DMGlobalToLocalBegin_Composite"
978 PetscErrorCode  DMGlobalToLocalBegin_Composite(DM dm,Vec gvec,InsertMode mode,Vec lvec)
979 {
980   PetscErrorCode         ierr;
981   struct DMCompositeLink *next;
982   PetscInt               cnt = 3;
983   PetscMPIInt            rank;
984   PetscScalar            *garray,*larray;
985   DM_Composite           *com = (DM_Composite*)dm->data;
986 
987   PetscFunctionBegin;
988   PetscValidHeaderSpecific(dm,DM_CLASSID,1);
989   PetscValidHeaderSpecific(gvec,VEC_CLASSID,2);
990   next = com->next;
991   if (!com->setup) {
992     ierr = DMSetUp(dm);CHKERRQ(ierr);
993   }
994   ierr = MPI_Comm_rank(((PetscObject)dm)->comm,&rank);CHKERRQ(ierr);
995   ierr = VecGetArray(gvec,&garray);CHKERRQ(ierr);
996   ierr = VecGetArray(lvec,&larray);CHKERRQ(ierr);
997 
998   /* loop over packed objects, handling one at at time */
999   while (next) {
1000     Vec      local,global;
1001     PetscInt N;
1002 
1003     ierr = DMGetGlobalVector(next->dm,&global);CHKERRQ(ierr);
1004     ierr = VecGetLocalSize(global,&N);CHKERRQ(ierr);
1005     ierr = VecPlaceArray(global,garray);CHKERRQ(ierr);
1006     ierr = DMGetLocalVector(next->dm,&local);CHKERRQ(ierr);
1007     ierr = VecPlaceArray(local,larray);CHKERRQ(ierr);
1008     ierr = DMGlobalToLocalBegin(next->dm,global,mode,local);CHKERRQ(ierr);
1009     ierr = DMGlobalToLocalEnd(next->dm,global,mode,local);CHKERRQ(ierr);
1010     ierr = VecResetArray(global);CHKERRQ(ierr);
1011     ierr = VecResetArray(local);CHKERRQ(ierr);
1012     ierr = DMRestoreGlobalVector(next->dm,&global);CHKERRQ(ierr);
1013     ierr = DMRestoreGlobalVector(next->dm,&local);CHKERRQ(ierr);
1014     cnt++;
1015     larray += next->nlocal;
1016     next    = next->next;
1017   }
1018 
1019   ierr = VecRestoreArray(gvec,PETSC_NULL);CHKERRQ(ierr);
1020   ierr = VecRestoreArray(lvec,PETSC_NULL);CHKERRQ(ierr);
1021   PetscFunctionReturn(0);
1022 }
1023 
1024 #undef __FUNCT__
1025 #define __FUNCT__ "DMGlobalToLocalEnd_Composite"
1026 PetscErrorCode  DMGlobalToLocalEnd_Composite(DM dm,Vec gvec,InsertMode mode,Vec lvec)
1027 {
1028   PetscFunctionBegin;
1029   PetscFunctionReturn(0);
1030 }
1031 
1032 EXTERN_C_BEGIN
1033 #undef __FUNCT__
1034 #define __FUNCT__ "DMCreate_Composite"
1035 PetscErrorCode  DMCreate_Composite(DM p)
1036 {
1037   PetscErrorCode ierr;
1038   DM_Composite   *com;
1039 
1040   PetscFunctionBegin;
1041   ierr = PetscNewLog(p,DM_Composite,&com);CHKERRQ(ierr);
1042   p->data = com;
1043   ierr = PetscObjectChangeTypeName((PetscObject)p,"DMComposite");CHKERRQ(ierr);
1044   com->n            = 0;
1045   com->next         = PETSC_NULL;
1046   com->nDM          = 0;
1047 
1048   p->ops->createglobalvector              = DMCreateGlobalVector_Composite;
1049   p->ops->createlocalvector               = DMCreateLocalVector_Composite;
1050   p->ops->createlocaltoglobalmapping      = DMCreateLocalToGlobalMapping_Composite;
1051   p->ops->createlocaltoglobalmappingblock = 0;
1052   p->ops->refine                          = DMRefine_Composite;
1053   p->ops->coarsen                         = DMCoarsen_Composite;
1054   p->ops->getinterpolation                = DMGetInterpolation_Composite;
1055   p->ops->getmatrix                       = DMGetMatrix_Composite;
1056   p->ops->getcoloring                     = DMGetColoring_Composite;
1057   p->ops->globaltolocalbegin              = DMGlobalToLocalBegin_Composite;
1058   p->ops->globaltolocalend                = DMGlobalToLocalEnd_Composite;
1059   p->ops->destroy                         = DMDestroy_Composite;
1060   p->ops->view                            = DMView_Composite;
1061   p->ops->setup                           = DMSetUp_Composite;
1062   PetscFunctionReturn(0);
1063 }
1064 EXTERN_C_END
1065 
1066 #undef __FUNCT__
1067 #define __FUNCT__ "DMCompositeCreate"
1068 /*@C
1069     DMCompositeCreate - Creates a vector packer, used to generate "composite"
1070       vectors made up of several subvectors.
1071 
1072     Collective on MPI_Comm
1073 
1074     Input Parameter:
1075 .   comm - the processors that will share the global vector
1076 
1077     Output Parameters:
1078 .   packer - the packer object
1079 
1080     Level: advanced
1081 
1082 .seealso DMDestroy(), DMCompositeAddDM(), DMCompositeScatter(),
1083          DMCompositeGather(), DMCreateGlobalVector(), DMCompositeGetISLocalToGlobalMappings(), DMCompositeGetAccess()
1084          DMCompositeGetLocalVectors(), DMCompositeRestoreLocalVectors(), DMCompositeGetEntries()
1085 
1086 @*/
1087 PetscErrorCode  DMCompositeCreate(MPI_Comm comm,DM *packer)
1088 {
1089   PetscErrorCode ierr;
1090 
1091   PetscFunctionBegin;
1092   PetscValidPointer(packer,2);
1093   ierr = DMCreate(comm,packer);CHKERRQ(ierr);
1094   ierr = DMSetType(*packer,DMCOMPOSITE);CHKERRQ(ierr);
1095   PetscFunctionReturn(0);
1096 }
1097