Actual source code: ex167.c
2: static char help[] = "Extract submatrices using unsorted indices. For SEQSBAIJ either sort both rows and columns, or sort none.\n\n";
3: /*
4: Take a 4x4 grid and form a 5-point stencil graph Laplacian over it.
5: Partition the grid into two subdomains by splitting into two in the j-direction (slowest varying).
6: Impose an overlap of 1 and order the subdomains with the j-direction varying fastest.
7: Extract the subdomain submatrices, one per rank.
8: */
9: /* Results:
10: Sequential:
11: - seqaij: will error out, if rows or columns are unsorted
12: - seqbaij: will extract submatrices correctly even for unsorted row or column indices
13: - seqsbaij: will extract submatrices correctly even for unsorted row and column indices (both must be sorted or not);
14: CANNOT automatically report inversions, because MatGetRow is not available.
15: MPI:
16: - mpiaij: will error out, if columns are unsorted
17: - mpibaij: will error out, if columns are unsorted.
18: - mpisbaij: will error out, if columns are unsorted; even with unsorted rows will produce correct submatrices;
19: CANNOT automatically report inversions, because MatGetRow is not available.
20: */
22: #include <petscmat.h>
23: #include <petscis.h>
25: int main(int argc, char **args)
26: {
27: Mat A, *S;
28: IS rowis[2], colis[2];
29: PetscInt n, N, i, j, k, l, nsub, Jlow[2] = {0, 1}, *jlow, Jhigh[2] = {3, 4}, *jhigh, row, col, *subindices, ncols;
30: const PetscInt *cols;
31: PetscScalar v;
32: PetscMPIInt rank, size, p, inversions, total_inversions;
33: PetscBool sort_rows, sort_cols, show_inversions;
35: PetscFunctionBeginUser;
36: PetscCall(PetscInitialize(&argc, &args, (char *)0, help));
37: PetscCallMPI(MPI_Comm_rank(PETSC_COMM_WORLD, &rank));
38: PetscCallMPI(MPI_Comm_size(PETSC_COMM_WORLD, &size));
39: PetscCheck(size < 3, PETSC_COMM_WORLD, PETSC_ERR_WRONG_MPI_SIZE, "A uniprocessor or two-processor example only.");
41: PetscCall(MatCreate(PETSC_COMM_WORLD, &A));
42: if (size > 1) {
43: n = 8;
44: N = 16;
45: } else {
46: n = 16;
47: N = 16;
48: }
49: PetscCall(MatSetSizes(A, n, n, N, N));
50: PetscCall(MatSetFromOptions(A));
51: PetscCall(MatSetUp(A));
53: /* Don't care if the entries are set multiple times by different procs. */
54: for (i = 0; i < 4; ++i) {
55: for (j = 0; j < 4; ++j) {
56: row = j * 4 + i;
57: v = -1.0;
58: if (i > 0) {
59: col = row - 1;
60: PetscCall(MatSetValues(A, 1, &row, 1, &col, &v, INSERT_VALUES));
61: }
62: if (i < 3) {
63: col = row + 1;
64: PetscCall(MatSetValues(A, 1, &row, 1, &col, &v, INSERT_VALUES));
65: }
66: if (j > 0) {
67: col = row - 4;
68: PetscCall(MatSetValues(A, 1, &row, 1, &col, &v, INSERT_VALUES));
69: }
70: if (j < 3) {
71: col = row + 4;
72: PetscCall(MatSetValues(A, 1, &row, 1, &col, &v, INSERT_VALUES));
73: }
74: v = 4.0;
75: PetscCall(MatSetValues(A, 1, &row, 1, &row, &v, INSERT_VALUES));
76: }
77: }
78: PetscCall(MatAssemblyBegin(A, MAT_FINAL_ASSEMBLY));
79: PetscCall(MatAssemblyEnd(A, MAT_FINAL_ASSEMBLY));
80: PetscCall(PetscPrintf(PETSC_COMM_WORLD, "Original matrix\n"));
81: PetscCall(MatView(A, PETSC_VIEWER_STDOUT_WORLD));
83: if (size > 1) {
84: nsub = 1; /* one subdomain per rank */
85: } else {
86: nsub = 2; /* both subdomains on rank 0 */
87: }
88: if (rank) {
89: jlow = Jlow + 1;
90: jhigh = Jhigh + 1;
91: } else {
92: jlow = Jlow;
93: jhigh = Jhigh;
94: }
95: sort_rows = PETSC_FALSE;
96: PetscCall(PetscOptionsGetBool(NULL, NULL, "-sort_rows", &sort_rows, NULL));
97: sort_cols = PETSC_FALSE;
98: PetscCall(PetscOptionsGetBool(NULL, NULL, "-sort_cols", &sort_cols, NULL));
99: for (l = 0; l < nsub; ++l) {
100: PetscCall(PetscMalloc1(12, &subindices));
101: k = 0;
102: for (i = 0; i < 4; ++i) {
103: for (j = jlow[l]; j < jhigh[l]; ++j) {
104: subindices[k] = j * 4 + i;
105: k++;
106: }
107: }
108: PetscCall(ISCreateGeneral(PETSC_COMM_SELF, 12, subindices, PETSC_OWN_POINTER, rowis + l));
109: if ((sort_rows && !sort_cols) || (!sort_rows && sort_cols)) {
110: PetscCall(ISDuplicate(rowis[l], colis + l));
111: } else {
112: PetscCall(PetscObjectReference((PetscObject)rowis[l]));
113: colis[l] = rowis[l];
114: }
115: if (sort_rows) PetscCall(ISSort(rowis[l]));
116: if (sort_cols) PetscCall(ISSort(colis[l]));
117: }
119: PetscCall(MatCreateSubMatrices(A, nsub, rowis, colis, MAT_INITIAL_MATRIX, &S));
121: show_inversions = PETSC_FALSE;
123: PetscCall(PetscOptionsGetBool(NULL, NULL, "-show_inversions", &show_inversions, NULL));
125: inversions = 0;
126: for (p = 0; p < size; ++p) {
127: if (p == rank) {
128: PetscCall(PetscPrintf(PETSC_COMM_SELF, "[%" PetscInt_FMT ":%" PetscInt_FMT "]: Number of subdomains: %" PetscInt_FMT ":\n", rank, size, nsub));
129: for (l = 0; l < nsub; ++l) {
130: PetscInt i0, i1;
131: PetscCall(PetscPrintf(PETSC_COMM_SELF, "[%" PetscInt_FMT ":%" PetscInt_FMT "]: Subdomain row IS %" PetscInt_FMT ":\n", rank, size, l));
132: PetscCall(ISView(rowis[l], PETSC_VIEWER_STDOUT_SELF));
133: PetscCall(PetscPrintf(PETSC_COMM_SELF, "[%" PetscInt_FMT ":%" PetscInt_FMT "]: Subdomain col IS %" PetscInt_FMT ":\n", rank, size, l));
134: PetscCall(ISView(colis[l], PETSC_VIEWER_STDOUT_SELF));
135: PetscCall(PetscPrintf(PETSC_COMM_SELF, "[%" PetscInt_FMT ":%" PetscInt_FMT "]: Submatrix %" PetscInt_FMT ":\n", rank, size, l));
136: PetscCall(MatView(S[l], PETSC_VIEWER_STDOUT_SELF));
137: if (show_inversions) {
138: PetscCall(MatGetOwnershipRange(S[l], &i0, &i1));
139: for (i = i0; i < i1; ++i) {
140: PetscCall(MatGetRow(S[l], i, &ncols, &cols, NULL));
141: for (j = 1; j < ncols; ++j) {
142: if (cols[j] < cols[j - 1]) {
143: 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));
144: inversions++;
145: }
146: }
147: PetscCall(MatRestoreRow(S[l], i, &ncols, &cols, NULL));
148: }
149: }
150: }
151: }
152: PetscCallMPI(MPI_Barrier(PETSC_COMM_WORLD));
153: }
154: if (show_inversions) {
155: PetscCallMPI(MPI_Reduce(&inversions, &total_inversions, 1, MPIU_INT, MPI_SUM, 0, PETSC_COMM_WORLD));
156: PetscCall(PetscPrintf(PETSC_COMM_WORLD, "*Total inversions: %" PetscInt_FMT "\n", total_inversions));
157: }
158: PetscCall(MatDestroy(&A));
160: for (l = 0; l < nsub; ++l) {
161: PetscCall(ISDestroy(&(rowis[l])));
162: PetscCall(ISDestroy(&(colis[l])));
163: }
164: PetscCall(MatDestroySubMatrices(nsub, &S));
165: PetscCall(PetscFinalize());
166: return 0;
167: }