Function random_regular 

pub fn random_regular<A>(n: usize) -> ArrayBase<OwnedRepr<A>, Dim<[usize; 2]>>
where
    A: Scalar + Lapack,

Generate random regular matrix

• Be sure that this it NOT a uniform distribution. Use it only for test purpose.
• This function uses rand::thread_rng. See random_regular_using for using another RNG.