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Re: ODE's again (sorry)
- From: Brian Gough <bjg at network-theory dot co dot uk>
- To: "Sam Halliday" <plendily at hotmail dot com>
- Cc: gsl-discuss at sources dot redhat dot com
- Date: Mon, 4 Mar 2002 22:31:30 +0000 (GMT)
- Subject: Re: ODE's again (sorry)
- References: <F51BwTXPx8XVccxXzLs0000472e@hotmail.com>
Sam Halliday writes:
> hello all,
> i have been having problems with the ODE's of gsl 1.1. i thought i
> had it mastered when i solved lane-emden (which is not disimilar to
> the thomas-fermi equation), but now i have moved onto solving 3
> simple newtonian motion equations, which need to have solutions
> from the other in order to calculate the next value...
> so i tried making 3 calls to the runge-kutta (4th order), which
> worked for me before, and if i solve for one of these 3 equations
> by itself, it seems to work, however if i change the step range in
> my solution to only solve for 1 value (instead of a whole range), i
> get a slight error in the 2nd calculated values with respect to the
> solution over a range, here is some sample data --solution by one
> call to my function (similar to the fixed-step example in the
> docs), solving for the whole range:
Have you tried stepping through the source code with the debugger?
Then you can see exactly what is being calculated.
regards
Brian