Actual source code: ex167.c
1: static char help[] = "Extract submatrices using unsorted indices. For SEQSBAIJ either sort both rows and columns, or sort none.\n\n";
2: /*
3: Take a 4x4 grid and form a 5-point stencil graph Laplacian over it.
4: Partition the grid into two subdomains by splitting into two in the j-direction (slowest varying).
5: Impose an overlap of 1 and order the subdomains with the j-direction varying fastest.
6: Extract the subdomain submatrices, one per rank.
7: */
8: /* Results:
9: Sequential:
10: - seqaij: will error out, if rows or columns are unsorted
11: - seqbaij: will extract submatrices correctly even for unsorted row or column indices
12: - seqsbaij: will extract submatrices correctly even for unsorted row and column indices (both must be sorted or not);
13: CANNOT automatically report inversions, because MatGetRow is not available.
14: MPI:
15: - mpiaij: will error out, if columns are unsorted
16: - mpibaij: will error out, if columns are unsorted.
17: - mpisbaij: will error out, if columns are unsorted; even with unsorted rows will produce correct submatrices;
18: CANNOT automatically report inversions, because MatGetRow is not available.
19: */
21: #include <petscmat.h>
22: #include <petscis.h>
24: int main(int argc, char **args)
25: {
26: Mat A, *S;
27: IS rowis[2], colis[2];
28: PetscInt n, N, i, j, k, l, nsub, Jlow[2] = {0, 1}, *jlow, Jhigh[2] = {3, 4}, *jhigh, row, col, *subindices, ncols;
29: const PetscInt *cols;
30: PetscScalar v;
31: PetscMPIInt rank, size, p, inversions, total_inversions;
32: PetscBool sort_rows, sort_cols, show_inversions;
34: PetscFunctionBeginUser;
35: PetscCall(PetscInitialize(&argc, &args, (char *)0, help));
36: PetscCallMPI(MPI_Comm_rank(PETSC_COMM_WORLD, &rank));
37: PetscCallMPI(MPI_Comm_size(PETSC_COMM_WORLD, &size));
38: PetscCheck(size < 3, PETSC_COMM_WORLD, PETSC_ERR_WRONG_MPI_SIZE, "A uniprocessor or two-processor example only.");
40: PetscCall(MatCreate(PETSC_COMM_WORLD, &A));
41: if (size > 1) {
42: n = 8;
43: N = 16;
44: } else {
45: n = 16;
46: N = 16;
47: }
48: PetscCall(MatSetSizes(A, n, n, N, N));
49: PetscCall(MatSetFromOptions(A));
50: PetscCall(MatSetUp(A));
52: /* Don't care if the entries are set multiple times by different procs. */
53: for (i = 0; i < 4; ++i) {
54: for (j = 0; j < 4; ++j) {
55: row = j * 4 + i;
56: v = -1.0;
57: if (i > 0) {
58: col = row - 1;
59: PetscCall(MatSetValues(A, 1, &row, 1, &col, &v, INSERT_VALUES));
60: }
61: if (i < 3) {
62: col = row + 1;
63: PetscCall(MatSetValues(A, 1, &row, 1, &col, &v, INSERT_VALUES));
64: }
65: if (j > 0) {
66: col = row - 4;
67: PetscCall(MatSetValues(A, 1, &row, 1, &col, &v, INSERT_VALUES));
68: }
69: if (j < 3) {
70: col = row + 4;
71: PetscCall(MatSetValues(A, 1, &row, 1, &col, &v, INSERT_VALUES));
72: }
73: v = 4.0;
74: PetscCall(MatSetValues(A, 1, &row, 1, &row, &v, INSERT_VALUES));
75: }
76: }
77: PetscCall(MatAssemblyBegin(A, MAT_FINAL_ASSEMBLY));
78: PetscCall(MatAssemblyEnd(A, MAT_FINAL_ASSEMBLY));
79: PetscCall(PetscPrintf(PETSC_COMM_WORLD, "Original matrix\n"));
80: PetscCall(MatView(A, PETSC_VIEWER_STDOUT_WORLD));
82: if (size > 1) {
83: nsub = 1; /* one subdomain per rank */
84: } else {
85: nsub = 2; /* both subdomains on rank 0 */
86: }
87: if (rank) {
88: jlow = Jlow + 1;
89: jhigh = Jhigh + 1;
90: } else {
91: jlow = Jlow;
92: jhigh = Jhigh;
93: }
94: sort_rows = PETSC_FALSE;
95: PetscCall(PetscOptionsGetBool(NULL, NULL, "-sort_rows", &sort_rows, NULL));
96: sort_cols = PETSC_FALSE;
97: PetscCall(PetscOptionsGetBool(NULL, NULL, "-sort_cols", &sort_cols, NULL));
98: for (l = 0; l < nsub; ++l) {
99: PetscCall(PetscMalloc1(12, &subindices));
100: k = 0;
101: for (i = 0; i < 4; ++i) {
102: for (j = jlow[l]; j < jhigh[l]; ++j) {
103: subindices[k] = j * 4 + i;
104: k++;
105: }
106: }
107: PetscCall(ISCreateGeneral(PETSC_COMM_SELF, 12, subindices, PETSC_OWN_POINTER, rowis + l));
108: if ((sort_rows && !sort_cols) || (!sort_rows && sort_cols)) {
109: PetscCall(ISDuplicate(rowis[l], colis + l));
110: } else {
111: PetscCall(PetscObjectReference((PetscObject)rowis[l]));
112: colis[l] = rowis[l];
113: }
114: if (sort_rows) PetscCall(ISSort(rowis[l]));
115: if (sort_cols) PetscCall(ISSort(colis[l]));
116: }
118: PetscCall(MatCreateSubMatrices(A, nsub, rowis, colis, MAT_INITIAL_MATRIX, &S));
120: show_inversions = PETSC_FALSE;
122: PetscCall(PetscOptionsGetBool(NULL, NULL, "-show_inversions", &show_inversions, NULL));
124: inversions = 0;
125: for (p = 0; p < size; ++p) {
126: if (p == rank) {
127: PetscCall(PetscPrintf(PETSC_COMM_SELF, "[%" PetscInt_FMT ":%" PetscInt_FMT "]: Number of subdomains: %" PetscInt_FMT ":\n", rank, size, nsub));
128: for (l = 0; l < nsub; ++l) {
129: PetscInt i0, i1;
130: PetscCall(PetscPrintf(PETSC_COMM_SELF, "[%" PetscInt_FMT ":%" PetscInt_FMT "]: Subdomain row IS %" PetscInt_FMT ":\n", rank, size, l));
131: PetscCall(ISView(rowis[l], PETSC_VIEWER_STDOUT_SELF));
132: PetscCall(PetscPrintf(PETSC_COMM_SELF, "[%" PetscInt_FMT ":%" PetscInt_FMT "]: Subdomain col IS %" PetscInt_FMT ":\n", rank, size, l));
133: PetscCall(ISView(colis[l], PETSC_VIEWER_STDOUT_SELF));
134: PetscCall(PetscPrintf(PETSC_COMM_SELF, "[%" PetscInt_FMT ":%" PetscInt_FMT "]: Submatrix %" PetscInt_FMT ":\n", rank, size, l));
135: PetscCall(MatView(S[l], PETSC_VIEWER_STDOUT_SELF));
136: if (show_inversions) {
137: PetscCall(MatGetOwnershipRange(S[l], &i0, &i1));
138: for (i = i0; i < i1; ++i) {
139: PetscCall(MatGetRow(S[l], i, &ncols, &cols, NULL));
140: for (j = 1; j < ncols; ++j) {
141: if (cols[j] < cols[j - 1]) {
142: PetscCall(PetscPrintf(PETSC_COMM_SELF, "***Inversion in row %" PetscInt_FMT ": col[%" PetscInt_FMT "] = %" PetscInt_FMT " < %" PetscInt_FMT " = col[%" PetscInt_FMT "]\n", i, j, cols[j], cols[j - 1], j - 1));
143: inversions++;
144: }
145: }
146: PetscCall(MatRestoreRow(S[l], i, &ncols, &cols, NULL));
147: }
148: }
149: }
150: }
151: PetscCallMPI(MPI_Barrier(PETSC_COMM_WORLD));
152: }
153: if (show_inversions) {
154: PetscCallMPI(MPI_Reduce(&inversions, &total_inversions, 1, MPIU_INT, MPI_SUM, 0, PETSC_COMM_WORLD));
155: PetscCall(PetscPrintf(PETSC_COMM_WORLD, "*Total inversions: %" PetscInt_FMT "\n", total_inversions));
156: }
157: PetscCall(MatDestroy(&A));
159: for (l = 0; l < nsub; ++l) {
160: PetscCall(ISDestroy(&(rowis[l])));
161: PetscCall(ISDestroy(&(colis[l])));
162: }
163: PetscCall(MatDestroySubMatrices(nsub, &S));
164: PetscCall(PetscFinalize());
165: return 0;
166: }