Mass spring system equation help

Hi all fellow Matlab users.

I'm fairly good a Matlab but I have encountered some difficulty in getting my function to work with ode45. I have a system with two springs and two masses which are attached to a wall. I am given two second order odes (x1'' = -((k1)*(x1 - L1))/m1 + ((k2)*(x2 - x1 - w1 - L2))/m1 & x2'' = -((k2)*(x2 - x1 - w1 - L2))/m2). There after I made the 2nd order odes into 4 1st order odes which would go into my function. The time span is from 0 - 20 and initial values of x1 = L1 and x2 = L1 + w1 + L2 + 6. Assume all the other variables to be = 1. L1 & L2 = free length of spring. m1 & m2 = masses. x1 & x2 = position of the masses. w1 & w2 = width of masses and k1 & k2 = stiffness of spring.

Any ideas on how i should approach this problem will be greatly appreciated.

Thank you

Answer 1

[Orion]

I think a question similar to this has been answered in this thread http://www.mathworks.com/matlabcentral/newsreader/view_thread/47243