[Bug-gsl] [bug #26255] gsl_odeiv_evolve_apply fails to restore t on step failure

[Brian Gough]

URL:
  <http://savannah.gnu.org/bugs/?26255>

                 Summary: gsl_odeiv_evolve_apply fails to restore t on step
failure
                 Project: GNU Scientific Library
            Submitted by: bjg
            Submitted on: Mon 20 Apr 2009 08:29:48 PM BST
                Category: Runtime error
                Severity: 3 - Normal
        Operating System: 
                  Status: Confirmed
             Assigned to: bjg
             Open/Closed: Open
                 Release: 1.12
         Discussion Lock: Any

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Details:

From: Taneli Kalvas <address@hidden>
To: address@hidden
Subject: [Bug-gsl] Bug in odeiv integrator
Date: Wed, 15 Apr 2009 22:47:08 +0300

Hi!

The behaviour of gsl_odeiv_evolve_apply() differs from documentation. 
The documentation says:

"If the user-supplied functions defined in the system dydt return a 
status other than GSL_SUCCESS the step will be aborted. In this case, t 
and y will be restored to their pre-step values and the error code from 
the user-supplied function will be returned."

The y values are restored, but the t value is not. This happens in case, 
where the control function has first rejected a step because of too 
large error and when taking a new step, the user function returns an 
error.

It is easy to get around this problem by resetting the t in case of user 
function errors, so this is easy to fix, but I hope the problem would be 
fixed internally in gsl_odeiv_evolve_apply() to prevent further headaches.

Thanks and best regards,
Taneli Kalvas

-- 
Taneli Kalvas
M.Sc., Researcher
Physics Department, room FL114
P.O. Box 35 (YFL)
40014 University of Jyväskylä, Finland
Phone: +358-44-314-1602
Fax:   +358-14-260-2351
Email: address@hidden




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File Attachments:


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Date: Mon 20 Apr 2009 08:29:48 PM BST  Name: ode.c  Size: 1kB   By: bjg

<http://savannah.gnu.org/bugs/download.php?file_id=17977>
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Date: Mon 20 Apr 2009 08:29:48 PM BST  Name: out.dat  Size: 1kB   By: bjg

<http://savannah.gnu.org/bugs/download.php?file_id=17978>

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