Re: ODE's again (sorry)

[Brian Gough <bjg at network-theory dot co dot uk>]

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