Function iron_shapes::math::fast_invsqrt_64

pub fn fast_invsqrt_64(x: f64) -> f64

Fast approximate computation of 1/sqrt(x). The error should be below 0.2%.

See: https://en.wikipedia.org/wiki/Fast_inverse_square_root And: http://www.lomont.org/papers/2003/InvSqrt.pdf