Function holder_table_hessian

pub fn holder_table_hessian<T>(param: &[T; 2]) -> [[T; 2]; 2]
where
    T: Float + FromPrimitive,

Hessian of the Holder table test function.

The test function has a discontinuity at $\sqrt{x_1^2+x_2^2} = \pi$, hence the Hessian can be NaN-valued.