Function rosenbrock

pub fn rosenbrock(x: &[f64], (a, b): (f64, f64)) -> f64

rosenbrock: f(x) = sum(i=0,i<N/2) (x{2i} -a)^2 + b(x{2i+1} - [x{2i}^2)^2

Rosenbrock’s banana function. Typically a=1, b=100

Defined only for even N.

Global minimum at origin [0,0, …, 0]

https://en.wikipedia.org/wiki/Rosenbrock_function

Sum of uncoupled 2D Rosenbrock problem variant.