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 >