function f=unc_n1_04(x)
%reference:
%note that you can get the formulation of unc_n1_04 from some
%aritcles,such as
%
%
%algorithm:
%below code is  edited according to 
%
%
% solution:
% where the bounds are -5<=x<=5, K=0;
% The global minimum is at x*= 0,and f(x*)= -.546182845904e-2;



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


K=0;
f=-20*exp(-0.2*(0.5*(K^2+x^2))^1/2)-exp(0.5*(cos(2*pi*K)+cos(2*pi*x)))+22.71282;