Function tan_rrule 

pub fn tan_rrule<S: ScalarAd>(result: S, cotangent: S) -> S

Reverse rule for tan.

Examples

use chainrules::tan_rrule;

let dy = tan_rrule(0.25_f64.tan(), 1.0);
assert!((dy - (1.0 + 0.25_f64.tan().powi(2))).abs() < 1e-12);