1 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 */ 9 10 #include <petsc/private/dmdaimpl.h> /*I "petscdmda.h" I*/ 11 12 /*@ 13 DMDAGlobalToNaturalAllCreate - Creates a scatter context that maps from the 14 global vector the entire vector to each processor in natural numbering 15 16 Collective on da 17 18 Input Parameter: 19 . da - the distributed array context 20 21 Output Parameter: 22 . scatter - the scatter context 23 24 Level: advanced 25 26 .seealso: `DMDAGlobalToNaturalEnd()`, `DMLocalToGlobalBegin()`, `DMDACreate2d()`, 27 `DMGlobalToLocalBegin()`, `DMGlobalToLocalEnd()`, `DMDACreateNaturalVector()` 28 @*/ 29 PetscErrorCode DMDAGlobalToNaturalAllCreate(DM da, VecScatter *scatter) { 30 PetscInt N; 31 IS from, to; 32 Vec tmplocal, global; 33 AO ao; 34 DM_DA *dd = (DM_DA *)da->data; 35 36 PetscFunctionBegin; 37 PetscValidHeaderSpecificType(da, DM_CLASSID, 1, DMDA); 38 PetscValidPointer(scatter, 2); 39 PetscCall(DMDAGetAO(da, &ao)); 40 41 /* create the scatter context */ 42 PetscCall(VecCreateMPIWithArray(PetscObjectComm((PetscObject)da), dd->w, dd->Nlocal, PETSC_DETERMINE, NULL, &global)); 43 PetscCall(VecGetSize(global, &N)); 44 PetscCall(ISCreateStride(PetscObjectComm((PetscObject)da), N, 0, 1, &to)); 45 PetscCall(AOPetscToApplicationIS(ao, to)); 46 PetscCall(ISCreateStride(PetscObjectComm((PetscObject)da), N, 0, 1, &from)); 47 PetscCall(VecCreateSeqWithArray(PETSC_COMM_SELF, dd->w, N, NULL, &tmplocal)); 48 PetscCall(VecScatterCreate(global, from, tmplocal, to, scatter)); 49 PetscCall(VecDestroy(&tmplocal)); 50 PetscCall(VecDestroy(&global)); 51 PetscCall(ISDestroy(&from)); 52 PetscCall(ISDestroy(&to)); 53 PetscFunctionReturn(0); 54 } 55 56 /*@ 57 DMDANaturalAllToGlobalCreate - Creates a scatter context that maps from a copy 58 of the entire vector on each processor to its local part in the global vector. 59 60 Collective on da 61 62 Input Parameter: 63 . da - the distributed array context 64 65 Output Parameter: 66 . scatter - the scatter context 67 68 Level: advanced 69 70 .seealso: `DMDAGlobalToNaturalEnd()`, `DMLocalToGlobalBegin()`, `DMDACreate2d()`, 71 `DMGlobalToLocalBegin()`, `DMGlobalToLocalEnd()`, `DMDACreateNaturalVector()` 72 @*/ 73 PetscErrorCode DMDANaturalAllToGlobalCreate(DM da, VecScatter *scatter) { 74 DM_DA *dd = (DM_DA *)da->data; 75 PetscInt M, m = dd->Nlocal, start; 76 IS from, to; 77 Vec tmplocal, global; 78 AO ao; 79 80 PetscFunctionBegin; 81 PetscValidHeaderSpecificType(da, DM_CLASSID, 1, DMDA); 82 PetscValidPointer(scatter, 2); 83 PetscCall(DMDAGetAO(da, &ao)); 84 85 /* create the scatter context */ 86 PetscCall(MPIU_Allreduce(&m, &M, 1, MPIU_INT, MPI_SUM, PetscObjectComm((PetscObject)da))); 87 PetscCall(VecCreateMPIWithArray(PetscObjectComm((PetscObject)da), dd->w, m, PETSC_DETERMINE, NULL, &global)); 88 PetscCall(VecGetOwnershipRange(global, &start, NULL)); 89 PetscCall(ISCreateStride(PetscObjectComm((PetscObject)da), m, start, 1, &from)); 90 PetscCall(AOPetscToApplicationIS(ao, from)); 91 PetscCall(ISCreateStride(PetscObjectComm((PetscObject)da), m, start, 1, &to)); 92 PetscCall(VecCreateSeqWithArray(PETSC_COMM_SELF, dd->w, M, NULL, &tmplocal)); 93 PetscCall(VecScatterCreate(tmplocal, from, global, to, scatter)); 94 PetscCall(VecDestroy(&tmplocal)); 95 PetscCall(VecDestroy(&global)); 96 PetscCall(ISDestroy(&from)); 97 PetscCall(ISDestroy(&to)); 98 PetscFunctionReturn(0); 99 } 100