Actual source code: ex211.c
1: static char help[] = "Tests MatCreateSubmatrix() in parallel.";
3: #include <petscmat.h>
4: #include <../src/mat/impls/aij/mpi/mpiaij.h>
6: PetscErrorCode ISGetSeqIS_SameColDist_Private(Mat mat, IS isrow, IS iscol, IS *isrow_d, IS *iscol_d, IS *iscol_o, const PetscInt *garray[])
7: {
8: Vec x, cmap;
9: const PetscInt *is_idx;
10: PetscScalar *xarray, *cmaparray;
11: PetscInt ncols, isstart, *idx, m, rstart, count;
12: Mat_MPIAIJ *a = (Mat_MPIAIJ *)mat->data;
13: Mat B = a->B;
14: Vec lvec = a->lvec, lcmap;
15: PetscInt i, cstart, cend, Bn = B->cmap->N;
16: MPI_Comm comm;
17: PetscMPIInt rank;
18: VecScatter Mvctx;
20: PetscFunctionBegin;
21: PetscCall(PetscObjectGetComm((PetscObject)mat, &comm));
22: PetscCallMPI(MPI_Comm_rank(comm, &rank));
23: PetscCall(ISGetLocalSize(iscol, &ncols));
25: /* (1) iscol is a sub-column vector of mat, pad it with '-1.' to form a full vector x */
26: PetscCall(MatCreateVecs(mat, &x, NULL));
27: PetscCall(VecDuplicate(x, &cmap));
28: PetscCall(VecSet(x, -1.0));
29: PetscCall(VecSet(cmap, -1.0));
31: PetscCall(VecDuplicate(lvec, &lcmap));
33: /* Get start indices */
34: PetscCallMPI(MPI_Scan(&ncols, &isstart, 1, MPIU_INT, MPI_SUM, comm));
35: isstart -= ncols;
36: PetscCall(MatGetOwnershipRangeColumn(mat, &cstart, &cend));
38: PetscCall(ISGetIndices(iscol, &is_idx));
39: PetscCall(VecGetArray(x, &xarray));
40: PetscCall(VecGetArray(cmap, &cmaparray));
41: PetscCall(PetscMalloc1(ncols, &idx));
42: for (i = 0; i < ncols; i++) {
43: xarray[is_idx[i] - cstart] = (PetscScalar)is_idx[i];
44: cmaparray[is_idx[i] - cstart] = (PetscScalar)(i + isstart); /* global index of iscol[i] */
45: idx[i] = is_idx[i] - cstart; /* local index of iscol[i] */
46: }
47: PetscCall(VecRestoreArray(x, &xarray));
48: PetscCall(VecRestoreArray(cmap, &cmaparray));
49: PetscCall(ISRestoreIndices(iscol, &is_idx));
51: /* Get iscol_d */
52: PetscCall(ISCreateGeneral(PETSC_COMM_SELF, ncols, idx, PETSC_OWN_POINTER, iscol_d));
53: PetscCall(ISGetBlockSize(iscol, &i));
54: PetscCall(ISSetBlockSize(*iscol_d, i));
56: /* Get isrow_d */
57: PetscCall(ISGetLocalSize(isrow, &m));
58: rstart = mat->rmap->rstart;
59: PetscCall(PetscMalloc1(m, &idx));
60: PetscCall(ISGetIndices(isrow, &is_idx));
61: for (i = 0; i < m; i++) idx[i] = is_idx[i] - rstart;
62: PetscCall(ISRestoreIndices(isrow, &is_idx));
64: PetscCall(ISCreateGeneral(PETSC_COMM_SELF, m, idx, PETSC_OWN_POINTER, isrow_d));
65: PetscCall(ISGetBlockSize(isrow, &i));
66: PetscCall(ISSetBlockSize(*isrow_d, i));
68: /* (2) Scatter x and cmap using aij->Mvctx to get their off-process portions (see MatMult_MPIAIJ) */
69: #if 0
70: if (!a->Mvctx_mpi1) {
71: /* a->Mvctx causes random 'count' in o-build? See src/mat/tests/runex59_2 */
72: a->Mvctx_mpi1_flg = PETSC_TRUE;
73: PetscCall(MatSetUpMultiply_MPIAIJ(mat));
74: }
75: Mvctx = a->Mvctx_mpi1;
76: #endif
77: Mvctx = a->Mvctx;
78: PetscCall(VecScatterBegin(Mvctx, x, lvec, INSERT_VALUES, SCATTER_FORWARD));
79: PetscCall(VecScatterEnd(Mvctx, x, lvec, INSERT_VALUES, SCATTER_FORWARD));
81: PetscCall(VecScatterBegin(Mvctx, cmap, lcmap, INSERT_VALUES, SCATTER_FORWARD));
82: PetscCall(VecScatterEnd(Mvctx, cmap, lcmap, INSERT_VALUES, SCATTER_FORWARD));
84: /* (3) create sequential iscol_o (a subset of iscol) and isgarray */
85: /* off-process column indices */
86: count = 0;
87: PetscInt *cmap1;
88: PetscCall(PetscMalloc1(Bn, &idx));
89: PetscCall(PetscMalloc1(Bn, &cmap1));
91: PetscCall(VecGetArray(lvec, &xarray));
92: PetscCall(VecGetArray(lcmap, &cmaparray));
93: for (i = 0; i < Bn; i++) {
94: if (PetscRealPart(xarray[i]) > -1.0) {
95: idx[count] = i; /* local column index in off-diagonal part B */
96: cmap1[count] = (PetscInt)(PetscRealPart(cmaparray[i])); /* column index in submat */
97: count++;
98: }
99: }
100: printf("[%d] Bn %d, count %d\n", rank, Bn, count);
101: PetscCall(VecRestoreArray(lvec, &xarray));
102: PetscCall(VecRestoreArray(lcmap, &cmaparray));
103: if (count != 6) {
104: printf("[%d] count %d != 6 lvec:\n", rank, count);
105: PetscCall(VecView(lvec, 0));
107: printf("[%d] count %d != 6 lcmap:\n", rank, count);
108: PetscCall(VecView(lcmap, 0));
109: SETERRQ(PETSC_COMM_SELF, PETSC_ERR_ARG_WRONGSTATE, "count %d != 6", count);
110: }
112: PetscCall(ISCreateGeneral(PETSC_COMM_SELF, count, idx, PETSC_COPY_VALUES, iscol_o));
113: /* cannot ensure iscol_o has same blocksize as iscol! */
115: PetscCall(PetscFree(idx));
117: *garray = cmap1;
119: PetscCall(VecDestroy(&x));
120: PetscCall(VecDestroy(&cmap));
121: PetscCall(VecDestroy(&lcmap));
122: PetscFunctionReturn(PETSC_SUCCESS);
123: }
125: int main(int argc, char **args)
126: {
127: Mat C, A;
128: PetscInt i, j, m = 3, n = 2, rstart, rend;
129: PetscMPIInt size, rank;
130: PetscScalar v;
131: IS isrow, iscol;
133: PetscFunctionBeginUser;
134: PetscCall(PetscInitialize(&argc, &args, NULL, help));
135: PetscCallMPI(MPI_Comm_rank(PETSC_COMM_WORLD, &rank));
136: PetscCallMPI(MPI_Comm_size(PETSC_COMM_WORLD, &size));
137: n = 2 * size;
139: PetscCall(MatCreate(PETSC_COMM_WORLD, &C));
140: PetscCall(MatSetSizes(C, PETSC_DECIDE, PETSC_DECIDE, m * n, m * n));
141: PetscCall(MatSetFromOptions(C));
142: PetscCall(MatSetUp(C));
144: /*
145: This is JUST to generate a nice test matrix, all processors fill up
146: the entire matrix. This is not something one would ever do in practice.
147: */
148: PetscCall(MatGetOwnershipRange(C, &rstart, &rend));
149: for (i = rstart; i < rend; i++) {
150: for (j = 0; j < m * n; j++) {
151: v = i + j + 1;
152: PetscCall(MatSetValues(C, 1, &i, 1, &j, &v, INSERT_VALUES));
153: }
154: }
156: PetscCall(MatAssemblyBegin(C, MAT_FINAL_ASSEMBLY));
157: PetscCall(MatAssemblyEnd(C, MAT_FINAL_ASSEMBLY));
159: /*
160: Generate a new matrix consisting of every second row and column of
161: the original matrix
162: */
163: PetscCall(MatGetOwnershipRange(C, &rstart, &rend));
164: /* Create parallel IS with the rows we want on THIS processor */
165: PetscCall(ISCreateStride(PETSC_COMM_WORLD, (rend - rstart) / 2, rstart, 2, &isrow));
166: /* Create parallel IS with the rows we want on THIS processor (same as rows for now) */
167: PetscCall(ISCreateStride(PETSC_COMM_WORLD, (rend - rstart) / 2, rstart, 2, &iscol));
169: IS iscol_d, isrow_d, iscol_o;
170: const PetscInt *garray;
171: PetscCall(ISGetSeqIS_SameColDist_Private(C, isrow, iscol, &isrow_d, &iscol_d, &iscol_o, &garray));
173: PetscCall(ISDestroy(&isrow_d));
174: PetscCall(ISDestroy(&iscol_d));
175: PetscCall(ISDestroy(&iscol_o));
176: PetscCall(PetscFree(garray));
178: PetscCall(MatCreateSubMatrix(C, isrow, iscol, MAT_INITIAL_MATRIX, &A));
179: PetscCall(MatCreateSubMatrix(C, isrow, iscol, MAT_REUSE_MATRIX, &A));
181: PetscCall(ISDestroy(&isrow));
182: PetscCall(ISDestroy(&iscol));
183: PetscCall(MatDestroy(&A));
184: PetscCall(MatDestroy(&C));
185: PetscCall(PetscFinalize());
186: return 0;
187: }