Function csc_rrule 

pub fn csc_rrule<S: ScalarAd>(x: S, cotangent: S) -> S

Reverse rule for csc.

Examples

use chainrules::csc_rrule;
let dy = csc_rrule(0.5_f64, 1.0);
assert!((dy + 0.5_f64.cos() / 0.5_f64.sin().powi(2)).abs() < 1e-12);