ackley.m

% 
% -------------------------------------------------------------------------
%    This file is part of BayesOpt, an efficient C++ library for 
%    Bayesian optimization.
%
%    Copyright (C) 2011-2015 Ruben Martinez-Cantin <rmcantin@unizar.es>
%
%    BayesOpt is free software: you can redistribute it and/or modify it 
%    under the terms of the GNU Affero General Public License as published by
%    the Free Software Foundation, either version 3 of the License, or
%    (at your option) any later version.
%
%    BayesOpt 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 Affero General Public License for more details.
%
%    You should have received a copy of the GNU Affero General Public License
%    along with BayesOpt.  If not, see <http://www.gnu.org/licenses/>.
% ------------------------------------------------------------------------
%

function y = ackley(x)
% Bounds -32.768, 32.768
% Min x = zeros, y = 0

n = length(x);
a = 20;
b = 0.2;
c = 2*pi;
ccx = cos(c*x);

y = -a*exp(-b*sqrt(sum(x.^2)/n)) - exp(sum(ccx)/n) + a + exp(1);