unc_nn_griewangk.m

it contains many classic Test Problems for Unconstrained Optimization such as camel6,treccani,goldst

function [fval]=unc_nn_Griewangk(x)
%reference:
%note that you can get the formulation of unc_nn_Griewangk from some
%aritcles,such as
%(1)Hartmut Pohlheim 'Genetic Algorithm Toolbox Test Functions'
%
%algorithm:
%below code is  edited according to 
%(1)Hartmut Pohlheim 'Genetic Algorithm Toolbox Test Functions'
%
%solution:
% where the bounds are -600<=x<=600;
%The global minimum is at x*=zeros(n,1),and f(x*)=0;
%there are about 200 minimia;
% Griewangk's function is similar to Rastrigin's function. It has many widespread local
% minima. However, the location of the minima are regularly distributed.

%Copyright:
% programmers:oiltowater.
% It comply with the GPL2.0
% Copyright 2006  oiltowater 

n=size(x,1);
producta=1;
for i=1:n
   producta=producta*cos(x(i,1)/sqrt(i));
end

fval=sum(x.*x)/4000-producta+1;