Function haversine 

pub fn haversine(theta: f64) -> f64

Calculates the haversine of the given angle.

Examples

use haversine_rs::haversine;

let theta = 0.0;
assert!(haversine(theta) == 0.0);

let theta = 1.0;
assert!(haversine(theta) == 0.22984884706593015);