Sign in to follow this  

Runge-Kutta 4th Order

Recommended Posts

I'm trying to do a particle simulation and I think my Runge-Kutta algorithm is working but I'm not sure if it is completely correct. The error may also be when I calculate the force but I think its in here. Am I doing it incorrectly? f=acceleration...
   // Runge-Kutta - 4th order
    void RungeKutta()
        // The stepsize
        const double h = 0.005;
        Vecd k1v = h * gVelocities;
        Vecd k1f = h * SumForces(gPositions, gVelocities);
        Vecd k2v = h * (gVelocities + k1f/2.0);
        Vecd k2f = h * SumForces(gPositions + k1v/2.0, gVelocities + k1f/2.0);
        Vecd k3v = h * (gVelocities + k2f/2.0);
        Vecd k3f = h * SumForces(gPositions + k2v/2.0, gVelocities + k2f/2.0);
        Vecd k4v = h * (gVelocities + k3f);
        Vecd k4f = h * SumForces(gPositions + k3v, gVelocities + k3f);

        gVelocities += k1f/6 + k2f/3 + k3f/3 + k4f/6;
        gPositions  += k1v/6 + k2v/3 + k3v/3 + k4v/6;

Share this post

Link to post
Share on other sites
A useful way to check an integrator is to apply it to a problem where you already know the answer. Then you can compare the numerical result to the analytic result to make sure the integrator is behaving as you expect.

Share this post

Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

Sign in to follow this