[Commons-Math] RungeKuttaIntegrator first step too large

[BIGNON Emmanuel <em...@thalesgroup.com>]

Hello,

I tried to integrate some equations using the RungeKuttaIntegrator class with an ending time within the first step. And it seems Commons Math does not adapt the first step size to match the ending time (It does it for next steps).

I also noticed that this problem has been solved in issue MATH-727 for Embedded Runge Kutta integrators (which has an adaptive step size).

Did I miss something or is that normal that the Embedded Runge Kutta integrators performs the step size check on first step but the Runge Kutta Integrator does not?

Thanks for your time,

Emmanuel

Re: [Commons-Math] RungeKuttaIntegrator first step too large

[luc <lu...@spaceroots.org>]

Le 2012-11-21 09:20, BIGNON Emmanuel a écrit :
> Hello,

Hi Emmanuel,

>
> I tried to integrate some equations using the RungeKuttaIntegrator
> class with an ending time within the first step. And it seems Commons
> Math does not adapt the first step size to match the ending time (It
> does it for next steps).
>
> I also noticed that this problem has been solved in issue MATH-727
> for Embedded Runge Kutta integrators (which has an adaptive step
> size).
>
> Did I miss something or is that normal that the Embedded Runge Kutta
> integrators performs the step size check on first step but the Runge
> Kutta Integrator does not?

It is not normal, it is a bug, thanks for reporting it.

Could you file a bug report in JIRA so we do not forget to fix it, with
a test case to reproduce the bug and ideally a patch to fix it?

best regards,
Luc

>
> Thanks for your time,
>
> Emmanuel


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