Fourth function by Price. The implementation is based on the defintion $$f(\mathbf{x}) = (2\mathbf{x}_1^3 \mathbf{x}_2 - \mathbf{x}_2^3)^2 + (6\mathbf{x}_1 - \mathbf{x}_2^2 + \mathbf{x}_2)^2$$ subject to \(\mathbf{x}_i \in [-500, 500]\).
makePriceN4Function()[smoof_single_objective_function]
W. L. Price, A Controlled Random Search Procedure for Global Optimisation, Computer journal, vol. 20, no. 4, pp. 367-370, 1977.