Function COOsort

XM/include/Sparse/sparseformat.h:17–27

// COOsort
template <typename T>
inline void COOsort(
    int* row_ids, int* col_ids, T* vals, const size_l nnz
) {
    // Use zip_iterator to create tuples (row, col, val) for sorting
    auto begin = thrust::make_zip_iterator(thrust::make_tuple(thrust::device_pointer_cast(row_ids), thrust::device_pointer_cast(col_ids), thrust::device_pointer_cast(vals)));
    auto end = thrust::make_zip_iterator(thrust::make_tuple(thrust::device_pointer_cast(row_ids + nnz), thrust::device_pointer_cast(col_ids + nnz), thrust::device_pointer_cast(vals + nnz)));

    // Sort by row first, then by column for identical rows
    thrust::sort(begin, end, thrust::less<thrust::tuple<int, int, T>>());
    return;
}

// convert CSC format in cusparse to CSR format in cusparse
// this routine needs additional memories on device