164   const PetscInt    *idxr, *idxc, *it;  in MatCreateSubMatrices_Htool()  local
175     PetscCall(ISGetIndices(irow[i], &idxr));  in MatCreateSubMatrices_Htool()
184           it = std::lower_bound(idxr, idxr + nrow, A->rmap->rstart);  in MatCreateSubMatrices_Htool()
185           if (it != idxr + nrow && *it == A->rmap->rstart) {    /* rmap->rstart in IS? */  in MatCreateSubMatrices_Htool()
186 …if (std::distance(idxr, it) + A->rmap->n <= nrow) { /* long enough IS to store the local diagonal …  in MatCreateSubMatrices_Htool()
195 …            m = std::distance(idxr, it); /* shift of the coefficient (0,0) of block D from above */  in MatCreateSubMatrices_Htool()
201 …            a->wrapper->copy_submatrix(nrow, m, idxr, idxc, ptr); /* vertical block B from above */  in MatCreateSubMatrices_Htool()
218                       a->wrapper->copy_submatrix(m, 1, idxr, idxc + m + k, ptr + (m + k) * nrow);  in MatCreateSubMatrices_Htool()
223 …a->wrapper->copy_submatrix(nrow, std::distance(it + A->rmap->n, idxr + nrow), idxr, idxc + m + A->…  in MatCreateSubMatrices_Htool()
240 …a->wrapper->copy_submatrix(std::distance(it + A->rmap->n, idxr + nrow), 1, it + A->rmap->n, idxc +…  in MatCreateSubMatrices_Htool()
250     if (!flg) a->wrapper->copy_submatrix(nrow, m, idxr, idxc, ptr); /* reassemble everything */  in MatCreateSubMatrices_Htool()
251     PetscCall(ISRestoreIndices(irow[i], &idxr));  in MatCreateSubMatrices_Htool()