function [y] = ackley(xx, a, b, c) %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% % % ACKLEY 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/ % %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% % % INPUTS: % % xx = [x1, x2, ..., xd] % a = constant (optional), with default value 20 % b = constant (optional), with default value 0.2 % c = constant (optional), with default value 2*pi % %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% d = length(xx); if (nargin < 4) c = 2*pi; end if (nargin < 3) b = 0.2; end if (nargin < 2) a = 20; end sum1 = 0; sum2 = 0; for ii = 1:d xi = xx(ii); sum1 = sum1 + xi^2; sum2 = sum2 + cos(c*xi); end term1 = -a * exp(-b*sqrt(sum1/d)); term2 = -exp(sum2/d); y = term1 + term2 + a + exp(1); end