Re: [Bug-gsl] gsl_odeiv_evolve_apply can only decrease step size, not increase

[Patrick Alken]

Hello,

  gsl_odeiv has been deprecated for several years and is replaced by
gsl_odeiv2. Please try the new interface and let us know if you have any
problems.

Patrick

On 10/13/2016 12:16 PM, Chris Rogers wrote:
> I am using gsl v1.15
>
> I note that ODE evolver, gsl_odeiv_evolve_apply, defined in
> gsl-1.15/ode-initval/evolve.c, can only decrease the step size in the
> integration. If I define a control function that results in an
> increasing step size, the evolver does not increase the step size.
>
> For example, if the integration goes from a region where the
> derivative changes quickly to one where the derivative changes slowly,
> the step size should get larger. This is not possible, even if a
> control function is defined that yields a large step size.
>
> Reviewing the source code, there is a code block like
>
>     if (hadjust_status == GSL_ODEIV_HADJ_DEC) {
>         <some stuff>
>     }
>
> but no code block like
>
>     if (hadjust_status == GSL_ODEIV_HADJ_INC) {
>         <some other stuff>
>     }
>
> Let me know if I can help in any way resolve the issue.
>
> Regards,
> Chris Rogers
>
>