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Re: NDSolve changed bahaviour in version 8?

• To: mathgroup at smc.vnet.net
• Subject: [mg116263] Re: NDSolve changed bahaviour in version 8?
• From: Oliver Ruebenkoenig <ruebenko at wolfram.com>
• Date: Wed, 9 Feb 2011 02:09:08 -0500 (EST)

On Tue, 8 Feb 2011, Michael Weyrauch wrote:

> Hello,
>
>    I am using NDSolve for the solution of large (say 10.000)
> sets of coupled non-linear ordinary differential equations.
>
> After "upgrading" to Mathematica 8 I observe that programs, that work
> well under Mathematica 6 (i.e. finish in about 3 hours) never finish
> in Mathematica 8 (i.e. I stop them after about 24 hours). The code is
> identical.
>
> Does anyone have similar experience? Does anyone know of changes
> in the NDSolve codebase, e.g. step size management? Is there
> any way to restore Mathematica 6 performance of NDSolve?
>
> Thanks for any ideas.
>

Hi Michael,

I am aware of two issues that could *possibly* cause this. But the 
telediagonis is tricky, if possible at all.

What - if any - options do you pass to NDSolve?

In any case it were good if you could send this to tech support to 
investigate. Thanks.

Oliver


> Michael Weyrauch
>
>