Re: ndsolve
- To: mathgroup at smc.vnet.net
- Subject: [mg22450] Re: ndsolve
- From: Jens-Peer Kuska <kuska at informatik.uni-leipzig.de>
- Date: Sun, 5 Mar 2000 00:23:46 -0500 (EST)
- Organization: Universitaet Leipzig
- References: <89ibli$mvi@smc.vnet.net>
- Sender: owner-wri-mathgroup at wolfram.com
Hi,
a) the Programming in Mathematica packages has a fixed stepsize
Runge-Kutta
method of order 4
<<ProgramingInMathematica`RungKutta`
will load the solver.
b) never uses an initial value solver without a step sizs control !
A constant stepsize solver is slower, make more steps and
accumulate rounding errors.
Hope that helps
Jens
Bernd Brandt wrote:
>
> Dear members,
>
> Does NDSolve have an option to use FIXED stepsize, e.g. in RungeKutta?
>
> NDSolve[{y'[x] == y[x], y[0] == 1}, y, {x, 0, 1}, Method -> RungeKutta,
> StartingStepSize -> 1, MaxStepSize -> 1]
>
> This obviously will not work since stepsize control still functions.
> How can i reduce the RungeKutta-Fehlberg to a simple RK4?
>
> Thanks,
> Bernd