Function _gr_vec_dot_strided 

pub unsafe extern "C" fn _gr_vec_dot_strided(
    res: gr_ptr,
    initial: gr_srcptr,
    subtract: c_int,
    vec1: gr_srcptr,
    stride1: slong,
    vec2: gr_srcptr,
    stride2: slong,
    len: slong,
    ctx: *mut gr_ctx_struct,
) -> c_int