Actual source code: dagtona.c
petsc-3.14.6 2021-03-30
2: /*
3: Tools to help solve the coarse grid problem redundantly.
4: Provides two scatter contexts that (1) map from the usual global vector
5: to all processors the entire vector in NATURAL numbering and (2)
6: from the entire vector on each processor in natural numbering extracts
7: out this processors piece in GLOBAL numbering
8: */
10: #include <petsc/private/dmdaimpl.h>
12: /*@
13: DMDAGlobalToNaturalAllCreate - Creates a scatter context that maps from the
14: global vector the entire vector to each processor in natural numbering
16: Collective on da
18: Input Parameter:
19: . da - the distributed array context
21: Output Parameter:
22: . scatter - the scatter context
24: Level: advanced
26: .seealso: DMDAGlobalToNaturalEnd(), DMLocalToGlobalBegin(), DMDACreate2d(),
27: DMGlobalToLocalBegin(), DMGlobalToLocalEnd(), DMDACreateNaturalVector()
28: @*/
29: PetscErrorCode DMDAGlobalToNaturalAllCreate(DM da,VecScatter *scatter)
30: {
32: PetscInt N;
33: IS from,to;
34: Vec tmplocal,global;
35: AO ao;
36: DM_DA *dd = (DM_DA*)da->data;
41: DMDAGetAO(da,&ao);
43: /* create the scatter context */
44: VecCreateMPIWithArray(PetscObjectComm((PetscObject)da),dd->w,dd->Nlocal,PETSC_DETERMINE,NULL,&global);
45: VecGetSize(global,&N);
46: ISCreateStride(PetscObjectComm((PetscObject)da),N,0,1,&to);
47: AOPetscToApplicationIS(ao,to);
48: ISCreateStride(PetscObjectComm((PetscObject)da),N,0,1,&from);
49: VecCreateSeqWithArray(PETSC_COMM_SELF,dd->w,N,NULL,&tmplocal);
50: VecScatterCreate(global,from,tmplocal,to,scatter);
51: VecDestroy(&tmplocal);
52: VecDestroy(&global);
53: ISDestroy(&from);
54: ISDestroy(&to);
55: return(0);
56: }
58: /*@
59: DMDANaturalAllToGlobalCreate - Creates a scatter context that maps from a copy
60: of the entire vector on each processor to its local part in the global vector.
62: Collective on da
64: Input Parameter:
65: . da - the distributed array context
67: Output Parameter:
68: . scatter - the scatter context
70: Level: advanced
72: .seealso: DMDAGlobalToNaturalEnd(), DMLocalToGlobalBegin(), DMDACreate2d(),
73: DMGlobalToLocalBegin(), DMGlobalToLocalEnd(), DMDACreateNaturalVector()
74: @*/
75: PetscErrorCode DMDANaturalAllToGlobalCreate(DM da,VecScatter *scatter)
76: {
78: DM_DA *dd = (DM_DA*)da->data;
79: PetscInt M,m = dd->Nlocal,start;
80: IS from,to;
81: Vec tmplocal,global;
82: AO ao;
87: DMDAGetAO(da,&ao);
89: /* create the scatter context */
90: MPIU_Allreduce(&m,&M,1,MPIU_INT,MPI_SUM,PetscObjectComm((PetscObject)da));
91: VecCreateMPIWithArray(PetscObjectComm((PetscObject)da),dd->w,m,PETSC_DETERMINE,NULL,&global);
92: VecGetOwnershipRange(global,&start,NULL);
93: ISCreateStride(PetscObjectComm((PetscObject)da),m,start,1,&from);
94: AOPetscToApplicationIS(ao,from);
95: ISCreateStride(PetscObjectComm((PetscObject)da),m,start,1,&to);
96: VecCreateSeqWithArray(PETSC_COMM_SELF,dd->w,M,NULL,&tmplocal);
97: VecScatterCreate(tmplocal,from,global,to,scatter);
98: VecDestroy(&tmplocal);
99: VecDestroy(&global);
100: ISDestroy(&from);
101: ISDestroy(&to);
102: return(0);
103: }