Re: [Bug-gsl] msadams.c:973 aborts with GSL_ESANITY

[Tuomo Keskitalo]

Hello,

On 02.10.2017 16:52, Michael Kaufman wrote:

> > Also, maybe check that the solver is not making a huge number of small 
> > steps (stiff problem?).
>
> Not sure how I do that.

Sorry, this is not documented, though it is used in test.c. For 
gsl_odeiv2_driver *d; after driver_apply() you can get the count of all 
steps from the evolve object via d->e->count and count of failed steps 
via d->e->failed_steps.

However, if other explicit ODE-solvers have no issues and your solution 
is always progressing at more or less constant rate, then it does point 
towards msadams. But let's first try to rule out problem-specific 
numerical issue. Could you please observe what happens in about 100 
evolve_apply steps just before tripping? There is example in the manual 
how to run evolve_apply manually (without driver). I'd be interested to 
know if solver step length changes a lot just before tripping or not.

It would of course be best if your problem could be reproduced in an 
example you can share, but let's see how far we can get without.

BR,
Tuomo

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