Function arf_approx_dot 

pub unsafe extern "C" fn arf_approx_dot(
    res: *mut arf_struct,
    initial: *const arf_struct,
    subtract: c_int,
    x: arf_srcptr,
    xstep: slong,
    y: arf_srcptr,
    ystep: slong,
    len: slong,
    prec: slong,
    rnd: arf_rnd_t,
)