optimization/test_functions/extended_rosenbrock_gradient1.m

   1 function g = extended_rosenbrock_gradient1(x)
   2   %
   3   % The gradient of the extended Rosenbrock function. See
   4   % extended_rosenbrock1.m for more information.
   5   %
   6   % Since the number of arguments is variable, we take a vector
   7   % instead of its individual components.
   8   %
   9   n = length(x);
  10
  11   if (odd(n))
  12     % 'm' below must be an integer.
  13     g = NA;
  14     return;
  15   end
  16
  17   m = n / 2;
  18   g = zeros(n, 1);
  19
  20   % The extended Rosenbrock is simply a sum of Rosenbrock
  21   % applications.
  22   for k = [ 1 : m ]
  23     y1 = x(2*k - 1);
  24     y2 = x(2*k);
  25
  26     g_k = rosenbrock_gradient(y1, y2);
  27
  28     g(2*k - 1) = g(2*k - 1) + g_k(1);
  29     g(2*k) = g(2*k) + g_k(2);
  30   end
  31 end