Function matyas_hessian

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

Hessian of Matyas test function.

Returns $$ \left( \begin{matrix} 0.52 & -0.48 \\ -0.48 & 0.52 \end{matrix} \right) $$ for any input.