doublep_der.m

Dispersion de Rutherford en Matlab

%doublep_der.m: returns the derivatives for the double pendulum problem
function ders = doublep_der(t,w,flag,L1,L2,m1,m2,g)
%w(1):theta1, w(2):theta1_dot, w(3):theta2, w(4):theta2_dot
tp=w(1)-w(3); cs=sin(tp); cc=cos(tp);
ta=m2*L2*cc/(m1+m2)/L1;
tb=(m2*L2*w(4).^2.*cs+(m1+m2)*g*sin(w(1)))/(m1+m2)/L1;
tc=(L1*tb.*cc+L1*w(2).^2.*cs-g*sin(w(3)))./(L2-ta.*L1.*cc);
ders=[w(2);-ta.*tc-tb;w(4);tc];