Equation of motion double pendulum

Hello,

I have to plot the time response of ninlineat system of double pendulum. I found the correct equation, but I do not how I can write on Matlab these equation. Could you explain me?

The equation of motion are :

(m1+m2)*l1*theta1(second) + m2*l2*theta2(second)*cos[theta2 - theta1] = m2*l2*[theta2(first)]^2 - (m1+m2)*g*sin[theta1]

l2*theta2(second) + l1*theta1(second)*cos[theta2 - theta1] = - l1*[theta1(first)]^2*sin[theta2 - theta1] - g*sin[theta2]

Thanks you

Answer 1

[Doug Hull]

Solve for the variables of interest. Then follow this:

http://blogs.mathworks.com/videos/2009/08/27/basics-implementing-a-formula-in-matlab/

[DABER]

Thanks you for your answer.

But, my problem is about i do not know how I can write the derivated of theta1 seconde( d²O/dt² ), theta1 first ( dO/dt ) and theta1 (O) on the équation.

I know i have to write

d²O/dt² = A dO/dt + B O, but i can not writing it on matlab :/

Thanks

[siti khadijah]

Thanks DABER :)