[SciPy-User] SciPy ODE integrator

Rob Clewley rob.clewley@gmail....
Wed Oct 27 13:24:06 CDT 2010


Sebastian,

> Thank you for your quick answer! Now it works with regular nonstiff-problems,
> but I'm still having problems with the stiff ones. I am trying to solve a stiff
> van-der-pol oscillator as described in matlab's ode15s reference (finish time
> tf=3000). The problem is that it takes too long, so long that I have to kill
> the process (in fact, if I change the finish time to tf=10, it takes
> approximately 1 minute to solve it whereas matlab takes 0.2s to solve it for
> tf=3000, and odeint took even less but with specified time points, which I don't
> want). Here is my code:


In case it helps, PyDSTool's Radau stiff integrator will solve this
system much faster than Matlab (with adaptive time step, of course),
and there is a van der pol example (actually involving a bifurcation
analysis) provided in the /tests directory, as PyCont_vanDerPol.py.

Let me know if you need help setting up. The full wiki documentation
pages are offline right now (the old server crashed) but some of the
core pages are being mirrored at my web site, linked from
pydstool.sourceforge.net. These do include installation information
for the Dopri and Radau integrators.

-Rob


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