Function ca_dot 

pub unsafe extern "C" fn ca_dot(
    res: *mut ca_struct,
    initial: *const ca_struct,
    subtract: c_int,
    x: ca_srcptr,
    xstep: slong,
    y: ca_srcptr,
    ystep: slong,
    len: slong,
    ctx: *mut ca_ctx_struct,
)