An improved cuckoo search optimization algorithm. Well competent and easy to use.
function y = Rastrigin(x)
% Rastrigin function
% Matlab Code by A. Hedar (Sep. 29, 2005).
% Last updated by Ahmed Tawfik (Apr. 30, 2013).
n = size(x,2);
s = 0;
for j = 1:n
s = s+(x(j)^2-10*cos(2*pi*x(j)));
y = 10*n+s;