Function argmin_testfunctions::schaffer_n4

pub fn schaffer_n4<T>(param: &[T; 2]) -> T
where
    T: Float + FromPrimitive,

Schaffer test function No. 4

Defined as

f(x_1, x_2) = 0.5 + (cos(sin(abs(x_1^2 - x_2^2)))^2 - 0.5) / (1 + 0.001*(x_1^2 + x_2^2))^2

where x_i \in [-100, 100].

The global minimum is at f(x_1, x_2) = f(0, 1.25313) = 0.291992.