Actual source code: spnd.c
2: #include <petscmat.h>
3: #include <petsc/private/matorderimpl.h>
5: /*
6: MatGetOrdering_ND - Find the nested dissection ordering of a given matrix.
7: */
8: PETSC_INTERN PetscErrorCode MatGetOrdering_ND(Mat mat, MatOrderingType type, IS *row, IS *col)
9: {
10: PetscInt i, *mask, *xls, *ls, nrow, *perm;
11: const PetscInt *ia, *ja;
12: PetscBool done;
13: Mat B = NULL;
15: MatGetRowIJ(mat, 1, PETSC_TRUE, PETSC_TRUE, &nrow, &ia, &ja, &done);
16: if (!done) {
17: MatConvert(mat, MATSEQAIJ, MAT_INITIAL_MATRIX, &B);
18: MatGetRowIJ(B, 1, PETSC_TRUE, PETSC_TRUE, &nrow, &ia, &ja, &done);
19: }
21: PetscMalloc4(nrow, &mask, nrow, &perm, nrow + 1, &xls, nrow, &ls);
22: SPARSEPACKgennd(&nrow, ia, ja, mask, perm, xls, ls);
23: if (B) {
24: MatRestoreRowIJ(B, 1, PETSC_TRUE, PETSC_TRUE, NULL, &ia, &ja, &done);
25: MatDestroy(&B);
26: } else {
27: MatRestoreRowIJ(mat, 1, PETSC_TRUE, PETSC_TRUE, NULL, &ia, &ja, &done);
28: }
30: /* shift because Sparsepack indices start at one */
31: for (i = 0; i < nrow; i++) perm[i]--;
33: ISCreateGeneral(PETSC_COMM_SELF, nrow, perm, PETSC_COPY_VALUES, row);
34: ISCreateGeneral(PETSC_COMM_SELF, nrow, perm, PETSC_COPY_VALUES, col);
35: PetscFree4(mask, perm, xls, ls);
36: return 0;
37: }