[SciPy-user] nullclines for nonlinear ODEs

Rob Clewley rob.clewley@gmail....
Wed Oct 31 09:26:46 CDT 2007

PyDSTool has a basic find_nullclines function which certainly works
for the L-V model and some other planar nonlinear systems. It's
naively implemented and I put it together quickly to get some
nullclines for a particular system, so use it at your own risk. You'll
find it in the Toolbox/phaseplane.py module, along with some functions
for finding fixed points, saddle manifolds, etc.


On 30/10/2007, LB <berthe.loic@gmail.com> wrote:
> Hi,
> It's really funny, I was planning to add an issue in the Cookbook
> about integrating ODE and I chose the Lokta-Volterra model as a basis
> too :-)
> I still haven't found the time to create the page, and I didn't plot
> any nullcline for the moment.
> I've just one remark on your example : if you look closely to your
> second graph, you can see that the trajectory crosses some arrows of
> the direction field. I had this problem too, before forcing matplotlib
> to use equal axis.
> --
> LB
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Robert H. Clewley, Ph. D.
Assistant Professor
Department of Mathematics and Statistics
Georgia State University
720 COE, 30 Pryor St
Atlanta, GA 30303, USA

tel: 404-413-6420   fax: 404-651-2246

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