MOP7 function from Van Valedhuizen's test suite.
makeMOP7Function()[smoof_multi_objective_function]
R. Viennet, C. Fonteix, and I. Marc, "Multicriteria optimization using a genetic algorithm for determining a Pareto set," Int. J. Syst. Sci., vol. 27, no. 2, pp. 255-260, 1996