function y = Razon_Dorada(f, xl, xu)

R =  (sqrt(5) -1)/2;
t = 0;

while (xu-xl > 0.0001)
    d = R*(xu - xl);
    x1 = xl + d;
    x2 = xu - d;
    disp([t, xl, x2, x1, xu, f(x2), f(x1)]);
    t = t+1;
    if f(x1) < f(x2)
        xl = x2;
    else 
        xu = x1;
    end;
    
    if f(x1) < f(x2)
        y = x1;
    else
        y=x2;
   end;    
end;