optimization/test_functions/extended_rosenbrock1.m

   1 function f = extended_rosenbrock1(x)
   2   %
   3   % The extended Rosenbrock function. See Dennis & Schnabel, Appendix
   4   % B, problem #1.
   5   %
   6   % This function has a minimum at x=(1,1,...,1) with f(x) == 0. The
   7   % suggested starting point is x0=(-1.2, 1,-1.2, 1,...,-1.2, 1).
   8   % Since the number of arguments is variable, we take a vector
   9   % instead of its individual components.
  10   %
  11   n = length(x);
  12
  13   if (odd(n))
  14     % 'm' below must be an integer.
  15     f = NA;
  16     return;
  17   end
  18
  19   m = n / 2;
  20   f = 0;
  21
  22   % The extended Rosenbrock is simply a sum of Rosenbrock
  23   % applications.
  24   for k = [ 1 : m ]
  25     y1 = x(2*k - 1);
  26     y2 = x(2*k);
  27     f_k = rosenbrock(y1, y2);
  28     f = f + f_k;
  29   end
  30 end