Golden ratio method

function x = golden_ratio_method(a, b, max_error, max_iter, my_function)

    c = (3 - sqrt(5))/2;

    for i = 1:max_iter

        x_1 = a + c*(b - a);
        x_2 = b - c*(b - a);

        if feval(my_function, x_1) > feval(my_function, x_2)
            a = x_1;
        elseif feval(my_function, x_2) > feval(my_function, x_1)
            b = x_2;
        else
            % Novi par tacaka ?
            a = x_1;
            b = x_2;
        end

        if abs(b-a) < max_error
            x = (a+b)/2;
            return;
        end

    end

    x = (a+b)/2;

end