Function beale

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

Beale test function

Defined as

$$ f(x_1, x_2) = (1.5 - x_1 + x_1 x_2)^2 + (2.25 - x_1 + x_1 x_2^2)^2 + (2.625 - x_1 + x_1 x_2^3)^2 $$

where $x_i \in [-4.5,\,4.5]$.

The global minimum is at $f(x_1, x_2) = f(3, 0.5) = 0$.