Function sincos_frule 

pub fn sincos_frule<S: ScalarAd>(x: S, dx: S) -> ((S, S), (S, S))

Forward rule for sincos.

Examples

use chainrules::sincos_frule;

let ((s, c), (ds, dc)) = sincos_frule(0.25_f64, 1.0);
assert!((ds - 0.25_f64.cos()).abs() < 1e-12);
assert!((dc + 0.25_f64.sin()).abs() < 1e-12);