Function perp_product 

pub fn perp_product(a_0: f64, a_1: f64, b_0: f64, b_1: f64) -> f64

2D vector perp product function: a x b.

• a_0, a_1 the first vector values.

• b_0, b_1 the second vector values.

• returns the perp product of the 2D vectors.