[SciPy-user] Regarding odeint timestep interval

Rob Clewley rob.clewley@gmail....
Fri Jun 26 15:33:21 CDT 2009


On Fri, Jun 26, 2009 at 8:52 AM, Ala Al-Shaibani<shaibani@ymail.com> wrote:
> Hello all.
> I'm wondering, if instead of passing timestep interval to odeint, I just
> pass start and end range (for example: t = [0, 10]), what timestep interval
> would odeint use as default in this case?

The external integrator code for odeint (namely the fortran code
lsoda, see below) will select its own initial time step by default.
This should be controllable with the optional parameters you can pass
through scipy's wrapper. See
http://docs.scipy.org/doc/scipy/reference/generated/scipy.integrate.odeint.html
for those, in particular the parameter h0.

If you want to know more explicitly how it calculates the initial time
step, you need to read the original lsoda code to see how it works it
out. See here at around the tagged line 160:

http://www.netlib.org/alliant/ode/prog/lsoda.f

-Rob


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