function S=test33(x)
% x0 = [0, 0]
% xo = [8.6998, 6.7665]
% S(xo) = -2

 S=-(sin(x(1)-x(2)/8)^2+sin(x(2)+x(1)/8)^2)/(1+sqrt((x(1)-8.6998)^2+(x(2)-6.7665)^2));

% 
%   [xo,Ot,nS]=swarm('test33',[0 0],0,[1 1],[-100 -100],[100 100],[],100,20)
%