1*8be712e4SBarry Smith #include <petscmat.h> 2*8be712e4SBarry Smith #include <petsc/private/matorderimpl.h> 3*8be712e4SBarry Smith 4*8be712e4SBarry Smith /* 5*8be712e4SBarry Smith MatGetOrdering_RCM - Find the Reverse Cuthill-McKee ordering of a given matrix. 6*8be712e4SBarry Smith */ 7*8be712e4SBarry Smith PETSC_INTERN PetscErrorCode MatGetOrdering_RCM(Mat mat, MatOrderingType type, IS *row, IS *col) 8*8be712e4SBarry Smith { 9*8be712e4SBarry Smith PetscInt i, *mask, *xls, nrow, *perm; 10*8be712e4SBarry Smith const PetscInt *ia, *ja; 11*8be712e4SBarry Smith PetscBool done; 12*8be712e4SBarry Smith 13*8be712e4SBarry Smith PetscFunctionBegin; 14*8be712e4SBarry Smith PetscCall(MatGetRowIJ(mat, 1, PETSC_TRUE, PETSC_TRUE, &nrow, &ia, &ja, &done)); 15*8be712e4SBarry Smith PetscCheck(done, PetscObjectComm((PetscObject)mat), PETSC_ERR_SUP, "Cannot get rows for matrix"); 16*8be712e4SBarry Smith 17*8be712e4SBarry Smith PetscCall(PetscMalloc3(nrow, &mask, nrow, &perm, 2 * nrow, &xls)); 18*8be712e4SBarry Smith PetscCall(SPARSEPACKgenrcm(&nrow, ia, ja, perm, mask, xls)); 19*8be712e4SBarry Smith PetscCall(MatRestoreRowIJ(mat, 1, PETSC_TRUE, PETSC_TRUE, NULL, &ia, &ja, &done)); 20*8be712e4SBarry Smith 21*8be712e4SBarry Smith /* shift because Sparsepack indices start at one */ 22*8be712e4SBarry Smith for (i = 0; i < nrow; i++) perm[i]--; 23*8be712e4SBarry Smith PetscCall(ISCreateGeneral(PETSC_COMM_SELF, nrow, perm, PETSC_COPY_VALUES, row)); 24*8be712e4SBarry Smith PetscCall(ISCreateGeneral(PETSC_COMM_SELF, nrow, perm, PETSC_COPY_VALUES, col)); 25*8be712e4SBarry Smith PetscCall(PetscFree3(mask, perm, xls)); 26*8be712e4SBarry Smith PetscFunctionReturn(PETSC_SUCCESS); 27*8be712e4SBarry Smith } 28