1 #include <petscmat.h>
2 #include <petsc/private/matorderimpl.h>
3
4 /*
5 MatGetOrdering_ND - Find the nested dissection ordering of a given matrix.
6 */
MatGetOrdering_ND(Mat mat,MatOrderingType type,IS * row,IS * col)7 PETSC_INTERN PetscErrorCode MatGetOrdering_ND(Mat mat, MatOrderingType type, IS *row, IS *col)
8 {
9 PetscInt i, *mask, *xls, *ls, nrow, *perm;
10 const PetscInt *ia, *ja;
11 PetscBool done;
12 Mat B = NULL;
13
14 PetscFunctionBegin;
15 PetscCall(MatGetRowIJ(mat, 1, PETSC_TRUE, PETSC_TRUE, &nrow, &ia, &ja, &done));
16 if (!done) {
17 PetscCall(MatConvert(mat, MATAIJ, MAT_INITIAL_MATRIX, &B));
18 PetscCall(MatGetRowIJ(B, 1, PETSC_TRUE, PETSC_TRUE, &nrow, &ia, &ja, &done));
19 }
20
21 PetscCall(PetscMalloc4(nrow, &mask, nrow, &perm, nrow + 1, &xls, nrow, &ls));
22 PetscCall(SPARSEPACKgennd(&nrow, ia, ja, mask, perm, xls, ls));
23 if (B) {
24 PetscCall(MatRestoreRowIJ(B, 1, PETSC_TRUE, PETSC_TRUE, NULL, &ia, &ja, &done));
25 PetscCall(MatDestroy(&B));
26 } else {
27 PetscCall(MatRestoreRowIJ(mat, 1, PETSC_TRUE, PETSC_TRUE, NULL, &ia, &ja, &done));
28 }
29
30 /* shift because Sparsepack indices start at one */
31 for (i = 0; i < nrow; i++) perm[i]--;
32
33 PetscCall(ISCreateGeneral(PETSC_COMM_SELF, nrow, perm, PETSC_COPY_VALUES, row));
34 PetscCall(ISCreateGeneral(PETSC_COMM_SELF, nrow, perm, PETSC_COPY_VALUES, col));
35 PetscCall(PetscFree4(mask, perm, xls, ls));
36 PetscFunctionReturn(PETSC_SUCCESS);
37 }
38