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Re: NDSolve precision and velocity problem

  • To: mathgroup at smc.vnet.net
  • Subject: [mg91315] Re: NDSolve precision and velocity problem
  • From: Jens-Peer Kuska <kuska at informatik.uni-leipzig.de>
  • Date: Fri, 15 Aug 2008 06:53:17 -0400 (EDT)
  • References: <g81378$o$1@smc.vnet.net>

Hi,

what mean "same methods as the LSODEA"
has five methods implemented, as listed in

http://www.netlib.org/odepack/opksmain.f

and you don't tell us what method you use.

And *why* you want to re-invent the wheel
if you already *have* a solution with LSODA.

Regards
   Jens


Joerg Schaber wrote:
> Hi,
> 
> I have an ODE system that takes lots of time to solve with NDSolve 
> (several minutes),
> whereas the same system with the FORTRAN solver LSODA
> solves the problem in an second.
> When I decrease the precision, e.g. AccuracyGoal->6, NDSolve crashes. It 
> often crashes, because it finds complex values in a less-than-comparison.
> 
> Maybe it's a method problem.
> How do I tell NDSolve, to use the same methods as the LSODEA solver?
> 
> Thanks,
> 
> joerg
> 
> 


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