Function radians_between 

pub fn radians_between(one: ThreeVec, other: ThreeVec) -> f64

Return the angle between two vectors in radians

Example

use std::f64;
use calcify::ThreeVec;
use calcify::radians_between;

let vec1 = ThreeVec::new(1.0,0.0,0.0);
let vec2 = ThreeVec::new(0.0,1.0,0.0);

assert_eq!(radians_between(vec1,vec2),f64::consts::PI/2.0);