[SciPy-User] lsoda vs. Coulomb friction

Charles R Harris charlesr.harris@gmail....
Wed Feb 3 19:29:34 CST 2010


On Wed, Feb 3, 2010 at 6:05 PM, Anne Archibald <peridot.faceted@gmail.com>wrote:

> 2010/2/3 David Goldsmith <d.l.goldsmith@gmail.com>:
>
> > "   :
> >     :
> > Returns
> >  -------
> >     :
> >     :
> >  infodict : dict, only returned if full_output == True
> >      Dictionary containing additional output information
> >         :
> >         :
> >      'mused'  a vector of method indicators for each successful time
> step:
> >               1: adams (nonstiff), 2: bdf (stiff)"
> >
> > Note that it's a _return_ value: apparently with odeint, you can't
> specify
> > which method to use, you can only "hear" which method the algorithm
> decided
> > to use for you.
>
> In particular, odeint always (?) starts with a non-stiff method and
> switches to a stiff method if the problem appears to warrant it. It
> does not seem that odeint ever switches back to a non-stiff method
> even if the problem enters a non-stiff region.
>
> In any case, I'm not sure there's any reason to think that a stiff
> solver will help with the OP's problem,


Me neither, what motivated that suggestion is that if the object "sticks",
then the ODE becomes an algebraic equation. Another WAG would be to try a
low order integrator. I'm rather curious to see what works best here.

<snip>

Chuck
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