Actual source code: sprcm.c
2: #include <petscmat.h>
3: #include <petsc/private/matorderimpl.h>
5: /*
6: MatGetOrdering_RCM - Find the Reverse Cuthill-McKee ordering of a given matrix.
7: */
8: PETSC_INTERN PetscErrorCode MatGetOrdering_RCM(Mat mat, MatOrderingType type, IS *row, IS *col)
9: {
10: PetscInt i, *mask, *xls, nrow, *perm;
11: const PetscInt *ia, *ja;
12: PetscBool done;
14: MatGetRowIJ(mat, 1, PETSC_TRUE, PETSC_TRUE, &nrow, &ia, &ja, &done);
17: PetscMalloc3(nrow, &mask, nrow, &perm, 2 * nrow, &xls);
18: SPARSEPACKgenrcm(&nrow, ia, ja, perm, mask, xls);
19: MatRestoreRowIJ(mat, 1, PETSC_TRUE, PETSC_TRUE, NULL, &ia, &ja, &done);
21: /* shift because Sparsepack indices start at one */
22: for (i = 0; i < nrow; i++) perm[i]--;
23: ISCreateGeneral(PETSC_COMM_SELF, nrow, perm, PETSC_COPY_VALUES, row);
24: ISCreateGeneral(PETSC_COMM_SELF, nrow, perm, PETSC_COPY_VALUES, col);
25: PetscFree3(mask, perm, xls);
26: return 0;
27: }