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: PetscFunctionBegin;
16: PetscCall(MatGetRowIJ(mat, 1, PETSC_TRUE, PETSC_TRUE, &nrow, &ia, &ja, &done));
17: if (!done) {
18: PetscCall(MatConvert(mat, MATAIJ, MAT_INITIAL_MATRIX, &B));
19: PetscCall(MatGetRowIJ(B, 1, PETSC_TRUE, PETSC_TRUE, &nrow, &ia, &ja, &done));
20: }
22: PetscCall(PetscMalloc4(nrow, &mask, nrow, &perm, nrow + 1, &xls, nrow, &ls));
23: PetscCall(SPARSEPACKgennd(&nrow, ia, ja, mask, perm, xls, ls));
24: if (B) {
25: PetscCall(MatRestoreRowIJ(B, 1, PETSC_TRUE, PETSC_TRUE, NULL, &ia, &ja, &done));
26: PetscCall(MatDestroy(&B));
27: } else {
28: PetscCall(MatRestoreRowIJ(mat, 1, PETSC_TRUE, PETSC_TRUE, NULL, &ia, &ja, &done));
29: }
31: /* shift because Sparsepack indices start at one */
32: for (i = 0; i < nrow; i++) perm[i]--;
34: PetscCall(ISCreateGeneral(PETSC_COMM_SELF, nrow, perm, PETSC_COPY_VALUES, row));
35: PetscCall(ISCreateGeneral(PETSC_COMM_SELF, nrow, perm, PETSC_COPY_VALUES, col));
36: PetscCall(PetscFree4(mask, perm, xls, ls));
37: PetscFunctionReturn(PETSC_SUCCESS);
38: }