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Re: ODE solver
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On Friday 29 October 2004 05:33 pm, you wrote:
> Ivo Alxneit writes:
> > int
> > jac_without (double t, const double y[], double *dfdy, double dfdt[],
> > void *params)
> > {
> > dfdy = NULL;
> > dfdt = NULL;
> > return GSL_SUCCESS;
> > }
> >
> > is jac_without correctly used?
>
> Subtle error---the variables dfdy and dfdt are local, so get discarded
> when the function exits.
aahhh yes (silly me)
>
> What you want to do is set the jacobian function pointer itself to
> NULL or put an abort() inside jac_without().
so you mean
gsl_odeiv_system sys_without = {func2, NULL, 2, &mu2};
in my code?
in this case i get the expected segfault. (question: shouldn't
gsl_odeiv_evolve_apply and related functions return an error and abort
gracefully?).
i assume that i was correct on that only bsimp uses the jacobian
matrix/function (maybe state in the manual that only algorithms where it is
explicity mentionned make use of the jacobian).
anyway thanks
- --
Dr. Ivo Alxneit
Laboratory for Solar Technology phone: +41 56 310 4092
CH-5232 Villigen fax: +41 56 310 2624
Paul Scherrer Institute http://solar.web.psi.ch
Switzerland gnupg key: 0x515E30C7
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