Function atan2 

pub fn atan2<F>(y: F, x: F) -> F
where
    F: Float,

The angle of the point (x, y) from the positive x axis, from -π to π, with y first as in C’s atan2. Zeros and infinities give C99’s angles: atan2(±0, -0) is ±π, and atan2(±∞, ±∞) is an odd multiple of ±π/4.