Function standardize

pub fn standardize<F>(design: Array2<F>) -> Array2<F>
where
    F: Float + FromPrimitive + DivAssign,

Returns a standardization of a design matrix where rows are seperate observations and columns are different dependent variables. Each quantity has its mean subtracted and is then divided by the standard deviation. The normalization by the standard deviation is not performed if there is only 1 observation, since such an operation is undefined.