1 function f = extended_powell1(x)
3 % The extended Powell function. See Dennis & Schnabel, Appendix B,
6 % This function has a minimum at x=(0,0,...,0) with f(x) == 0. The
7 % suggested starting point is x0=(3, -1, 0, 1,..., 3, -1, 0, 1).
8 % Since the number of arguments is variable, we take a vector
9 % instead of its individual components.
14 % 'm' below must be an integer.
22 % The extended Powell is simply a sum of Powell
30 f_k = powell(y1,y2,y3,y4);