function S=test(x)
% x0 = [3, 1]
% xo = [7.917, 7.917]
% S(xo) = -7.8856

 S=-sqrt(x(1)*x(2))*sin(x(1)).* sin(x(2));

% 
%   [xo,Ot,nS]=swarm('test28',[3 1],0,[1 1],[0 0],[10 10],[],100,20)
%