# Python, RungeKutta and first-order differential equation system.

1. Dec 13, 2008

### MaxManus

2. Relevant equations

The equation is, given to me by lurflurf,:
mv' + f(v ) + s(u) = F(t), t > 0, u(0) = U0, v (0) = V0
where v=u'
For the record the equation was:
mu'' + f(u' ) + s(u) = F(t), t > 0, u(0) = U0, u' (0) = V0 .

3. The attempt at a solution

Code (Text):
def rhs(u, t):
return [u[1],
(1./m)*(external(t) - friction(u[1]) - spring(u[0]))]
This is the solution, but I don't get how yuu go from the equation to rhs.
Can someone help me?

2. Dec 13, 2008

### MaxManus

Re: Python, RukgeKutta and first-order differential equation system.

Here is the page with the exercises: http://www.ifi.uio.no/~inf1100/ODE_project.pdf" [Broken]

The equation is given in 11.36 and it is 11.37 I need help with.
The solution is http://www.ifi.uio.no/~inf1100/live-programming/oscillator_v1.py" [Broken]

ODESolver http://www.ifi.uio.no/~inf1100/src/oo/ODESolver.py" [Broken]

Scitools contains array, plot etc

Last edited by a moderator: May 3, 2017