I am trying to find the global minimum of a schwefel function which is 0 at [420.9687,..., 420.9687]. I have used 'fmincon', Particle swarm Optimization algorithm (I'm using my code for this approach) and some other evolutionary algorithms. But none of them is giving global minimum at 0, All are giving some large positive value. Can anybody tell me how can I find global minimum of the schwefel function.
function y = schwefel(x)
s = sum(-x.*sin(sqrt(abs(x))));
y = 418.9829*length(x) + s;