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Re: Symplectic integration and Interpolating function

• To: mathgroup at smc.vnet.net
• Subject: [mg45562] Re: Symplectic integration and Interpolating function
• From: "Jens-Peer Kuska" <kuska at informatik.uni-leipzig-de>
• Date: Wed, 14 Jan 2004 01:26:15 -0500 (EST)
• Organization: Uni Leipzig
• References: <bu0do8$an9$1@smc.vnet.net>
• Sender: owner-wri-mathgroup at wolfram.com

Hi,



load :

Needs["DifferentialEquations`NDSolveUtilities`"];

and use the:

DifferentialEquations`NDSolveUtilities`Private`GetGridData[]

from this package.

Regards
  Jens

"Guibout" <guibout at ifrance.com> schrieb im Newsbeitrag
news:bu0do8$an9$1 at smc.vnet.net...
> Hi,
> I am using symplectic integrators to integrate a set of ode. One
> advantage of these integrators is that some properties are exactly
> preserved at the vertices. Therefore, it may be of interest to look at
> the values of the functions at the vertices. My question is the following:
> How do I find the vertices? NDSolve returns only an interpolating
> functions and some symplectic integrators have variable time steps, so
> even if I set the starting step size, I don't have any information on
> the next steps.
> Thanks
> Vincent
>