Two-dimensional test function based on the function defintion $$f(\mathbf{x}) = (\mathbf{x}_1^2 + \mathbf{x}_2 - 11)^2 + (\mathbf{x}_1 + \mathbf{x}_2^2 - 7)^2$$ with box-constraings \(\mathbf{x}_i \in [-5, 5], i = 1, 2\).
makeHimmelblauFunction()[smoof_single_objective_function]
D. M. Himmelblau, Applied Nonlinear Programming, McGraw-Hill, 1972.