Function tilde_matrix 

pub fn tilde_matrix(v: &Vector3<f64>) -> Matrix3<f64>

Returns the skew-symmetric matrix (also known as the tilde matrix) corresponding to the provided 3D vector.

The skew-symmetric matrix of a vector v is defined as:

 0   -v.z  v.y
 v.z  0   -v.x
-v.y  v.x  0

This matrix has the property that for any vector w, the cross product v x w can be computed as the matrix product of the skew-symmetric matrix of v and w.