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Re: [Help-gsl] odeiv2 rk2imp driver time step

From: Tuomo Keskitalo
Subject: Re: [Help-gsl] odeiv2 rk2imp driver time step
Date: Thu, 22 Dec 2011 08:34:43 +0200
User-agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv: Gecko/20110921 Thunderbird/3.1.15


On 12/22/2011 12:07 AM, Farkas, Illes wrote:

5s ) later there is an update when gsl_odeiv2_driver_apply returns the
FAILURE value: -1. After logging the current time directly from the
"function" and "jacobian" (used by the gsl_odeiv2_system, which is
driver by the driver), I found that this particular update fails,
because the time step is halved again and again until it reaches the
limit of numerical precision.

Sounds like you're driving into a singularity.

Try different steppers (msbdf, bsimp). If they're all stopping about there, the problem might be with your system. I guess you either have a bug in rhs function or jacobian code, or your system really has a singluarity in it. Or maybe you just have inappropriate tolerances in relation to your system?



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