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