function [y] = griewank(xx) %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% % % GRIEWANK FUNCTION % % Authors: Sonja Surjanovic, Simon Fraser University % Derek Bingham, Simon Fraser University % Questions/Comments: Please email Derek Bingham at dbingham@stat.sfu.ca. % % Copyright 2013. Derek Bingham, Simon Fraser University. % % THERE IS NO WARRANTY, EXPRESS OR IMPLIED. WE DO NOT ASSUME ANY LIABILITY % FOR THE USE OF THIS SOFTWARE. If software is modified to produce % derivative works, such modified software should be clearly marked. % Additionally, this program is free software; you can redistribute it % and/or modify it under the terms of the GNU General Public License as % published by the Free Software Foundation; version 2.0 of the License. % Accordingly, this program is distributed in the hope that it will be % useful, but WITHOUT ANY WARRANTY; without even the implied warranty % of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU % General Public License for more details. % % For function details and reference information, see: % http://www.sfu.ca/~ssurjano/ % %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% % % INPUT: % % xx = [x1, x2, ..., xd] % %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% d = length(xx); sum = 0; prod = 1; for ii = 1:d xi = xx(ii); sum = sum + xi^2/4000; prod = prod * cos(xi/sqrt(ii)); end y = sum - prod + 1; end