Actual source code: sprcm.c
1: #include <petscmat.h>
2: #include <petsc/private/matorderimpl.h>
4: /*
5: MatGetOrdering_RCM - Find the Reverse Cuthill-McKee ordering of a given matrix.
6: */
7: PETSC_INTERN PetscErrorCode MatGetOrdering_RCM(Mat mat, MatOrderingType type, IS *row, IS *col)
8: {
9: PetscInt i, *mask, *xls, nrow, *perm;
10: const PetscInt *ia, *ja;
11: PetscBool done;
13: PetscFunctionBegin;
14: PetscCall(MatGetRowIJ(mat, 1, PETSC_TRUE, PETSC_TRUE, &nrow, &ia, &ja, &done));
15: PetscCheck(done, PetscObjectComm((PetscObject)mat), PETSC_ERR_SUP, "Cannot get rows for matrix");
17: PetscCall(PetscMalloc3(nrow, &mask, nrow, &perm, 2 * nrow, &xls));
18: PetscCall(SPARSEPACKgenrcm(&nrow, ia, ja, perm, mask, xls));
19: PetscCall(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: PetscCall(ISCreateGeneral(PETSC_COMM_SELF, nrow, perm, PETSC_COPY_VALUES, row));
24: PetscCall(ISCreateGeneral(PETSC_COMM_SELF, nrow, perm, PETSC_COPY_VALUES, col));
25: PetscCall(PetscFree3(mask, perm, xls));
26: PetscFunctionReturn(PETSC_SUCCESS);
27: }