function y = x2_dot(x)
u =  x(1); % gaya masukan [Newton]
x3 = x(2); % sudut teta sesaat
x4 = x(3); % kecepatan sudut sesaat
g = 10 ; % percepatan gravitasi 10 m/sec2
l = 0.6 ; % panjang batang 60 cm
M = 0.25 ; % Massa kereta 250 gram
m = 0.025 ; % massa pendulum 25 gram
y = (u - (0.5*m*g*sin(2*x3)) + (m*l*(x4^2)*sin(x3)))/(M + m*(sin(x3))^2);