fuction[x, f, it] = Powell(fun, x0, epsilon)
n = length(x0);
u = eye(n);
x = x0;
x1 = x0 + 2 * epsilon;
it = 0;

while max(abs(x - x1)) > epsilon
 it = it + 1;
 ti = x;
 for i = 1:n
  teta = ZlatniPresek(fun, -10, 10, epsilon);
  ti = ti + teta*u(:,i);
 end
 u = [u(:, 2:n)  ti-x];
 x1 = x;
 teta = parabola(fun, u(:, n), ti, epsilon);
 x = ti + teta*u(:, n);
end
f = feval(fun, x);