1*8be712e4SBarry Smith #include <petscmat.h>
2*8be712e4SBarry Smith #include <petsc/private/matorderimpl.h>
3*8be712e4SBarry Smith
4*8be712e4SBarry Smith /*
5*8be712e4SBarry Smith MatGetOrdering_ND - Find the nested dissection ordering of a given matrix.
6*8be712e4SBarry Smith */
MatGetOrdering_ND(Mat mat,MatOrderingType type,IS * row,IS * col)7*8be712e4SBarry Smith PETSC_INTERN PetscErrorCode MatGetOrdering_ND(Mat mat, MatOrderingType type, IS *row, IS *col)
8*8be712e4SBarry Smith {
9*8be712e4SBarry Smith PetscInt i, *mask, *xls, *ls, nrow, *perm;
10*8be712e4SBarry Smith const PetscInt *ia, *ja;
11*8be712e4SBarry Smith PetscBool done;
12*8be712e4SBarry Smith Mat B = NULL;
13*8be712e4SBarry Smith
14*8be712e4SBarry Smith PetscFunctionBegin;
15*8be712e4SBarry Smith PetscCall(MatGetRowIJ(mat, 1, PETSC_TRUE, PETSC_TRUE, &nrow, &ia, &ja, &done));
16*8be712e4SBarry Smith if (!done) {
17*8be712e4SBarry Smith PetscCall(MatConvert(mat, MATAIJ, MAT_INITIAL_MATRIX, &B));
18*8be712e4SBarry Smith PetscCall(MatGetRowIJ(B, 1, PETSC_TRUE, PETSC_TRUE, &nrow, &ia, &ja, &done));
19*8be712e4SBarry Smith }
20*8be712e4SBarry Smith
21*8be712e4SBarry Smith PetscCall(PetscMalloc4(nrow, &mask, nrow, &perm, nrow + 1, &xls, nrow, &ls));
22*8be712e4SBarry Smith PetscCall(SPARSEPACKgennd(&nrow, ia, ja, mask, perm, xls, ls));
23*8be712e4SBarry Smith if (B) {
24*8be712e4SBarry Smith PetscCall(MatRestoreRowIJ(B, 1, PETSC_TRUE, PETSC_TRUE, NULL, &ia, &ja, &done));
25*8be712e4SBarry Smith PetscCall(MatDestroy(&B));
26*8be712e4SBarry Smith } else {
27*8be712e4SBarry Smith PetscCall(MatRestoreRowIJ(mat, 1, PETSC_TRUE, PETSC_TRUE, NULL, &ia, &ja, &done));
28*8be712e4SBarry Smith }
29*8be712e4SBarry Smith
30*8be712e4SBarry Smith /* shift because Sparsepack indices start at one */
31*8be712e4SBarry Smith for (i = 0; i < nrow; i++) perm[i]--;
32*8be712e4SBarry Smith
33*8be712e4SBarry Smith PetscCall(ISCreateGeneral(PETSC_COMM_SELF, nrow, perm, PETSC_COPY_VALUES, row));
34*8be712e4SBarry Smith PetscCall(ISCreateGeneral(PETSC_COMM_SELF, nrow, perm, PETSC_COPY_VALUES, col));
35*8be712e4SBarry Smith PetscCall(PetscFree4(mask, perm, xls, ls));
36*8be712e4SBarry Smith PetscFunctionReturn(PETSC_SUCCESS);
37*8be712e4SBarry Smith }
38