function F = mfun(q,v)
global g l1 l2 m1 m2
F = zeros(2,1);
F(1) = -m2*l2*sin(q(1)-q(2))*v(2)^2-(m1+m2)*g*sin(q(1));
F(2) =  m2*l1*sin(q(1)-q(2))*v(1)^2-m2*g*sin(q(2));