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Re: NDSolve is using Solve?

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  • Subject: [mg117146] Re: NDSolve is using Solve?
  • From: Oliver Ruebenkoenig <ruebenko at>
  • Date: Thu, 10 Mar 2011 06:14:14 -0500 (EST)

On Wed, 9 Mar 2011, J.Frazer wrote:

> Hello everyone,
> This is my first time posting so my apologies if I'm going about this
> the wrong way. I'm having the following problem:
> I'm using NDSolve but its not managing to get to the solution even if I
> leave it running over the weekend. If I greatly simplify one of the
> equations I can get a result but in either case I get the error messages
> Solve:: incnst
> Solve:: ifun
> This worries me as if its trying to simplify analytically, presumably as
> the equations becomes more complicated this will become incredibly time
> consuming.
> Do people agree this may be the cause of the long running time? If so,
> is there a way of stopping NDSolve from using Solve?
> Cheers,
> Jonny=
Hi Jonny,

yes NDSolve uses Solve internally but that is only for pre processing 
purposes. If this is really the cause for the slow NDSolve (maybe it is a 
hard problem...)  It were best if you could send some working code, then 
we could have a look at it and see if anything can be done.


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