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: }