From bug-request at octave dot org Tue Nov 29 23:56:34 2005
Subject: lsode crashes with integration method stiff and maximum order != -1
From: "John W. Eaton" <jwe at bevo dot che dot wisc dot edu>
To: Gero Putzar <gero at friction3 dot pi dot tu-berlin dot de>
Cc: bug at octave dot org
Date: Wed, 30 Nov 2005 00:56:22 -0500

On 17-Nov-2005, Gero Putzar wrote:

| To: bug at octave dot org
| Cc: gero
| Subject: lsode crashes with integration method stiff and maximum order != -1
| 
| Bug report for Octave 2.1.69 configured for i386-pc-linux-gnu
| 
| Description:
| -----------
| 
| octave stops with a segmentation fault, when integrating an ODE with the 
| method 'stiff' and the lsode_option maximum order set to a value between 
| 1 and 5.
| 
| Repeat-By:
| ---------
| 
| %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
| %% dot x = v
| %% dot v = -F(a-x) - v - k(x-v0*t)
| %% F(x) = 0.5*(x^(-13) - x^(-7))
| 
| function xdot = f(x,t)
|   xdot = zeros(2,1);
|   F = 0.5*((2.0 - x(1))^(-13) - (2.0 - x(1))^(-7));
|   xdot(1) = x(2);
|   xdot(2) = -F - x(2) - (x(1)-t);
| endfunction
| %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
| 
| x0 = [-1.0 ; 1];
| tvec = 0:0.2:20;
| 
| lsode_options('integration method', 'stiff');
| lsode_options('relative tolerance', 1E-3);
| lsode_options('maximum order', 5);
| 
| ignore_function_time_stamp = 'all';
| t = cputime ();
| [x, istate, msg] = lsode ('f', x0, tvec);
| disp(['Finished. cputime:', num2str(cputime () - t)]);
| ignore_function_time_stamp = 'system';
| 
| if (istate != 2)
|   error( msg );
| else
|   plot(tvec, x);
|   pause;
| endif

Please try the following patch.

Thanks,

jwe

liboctave/ChangeLog:

2005-11-30  John W. Eaton  <jwe at octave dot org>

	* LSODE.cc (LSODE::do_integrate (double)): Resize iwork and rwork
	before setting any values in either array.


Index: liboctave/LSODE.cc
===================================================================
RCS file: /usr/local/cvsroot/octave/liboctave/LSODE.cc,v
retrieving revision 1.56.2.1
diff -u -r1.56.2.1 LSODE.cc
--- liboctave/LSODE.cc	26 Apr 2005 19:43:54 -0000	1.56.2.1
+++ liboctave/LSODE.cc	30 Nov 2005 05:48:07 -0000
 at @ -153,6 +153,16 @@
 
       maxord = maximum_order ();
 
+      iwork.resize (liw);
+
+      for (int i = 4; i < 9; i++)
+	iwork(i) = 0;
+
+      rwork.resize (lrw);
+
+      for (int i = 4; i < 9; i++)
+	rwork(i) = 0;
+
       if (maxord >= 0)
 	{
 	  if (maxord > 0 && maxord <= max_maxord)
 at @ -169,16 +179,6 @@
 	    }
 	}
 
-      iwork.resize (liw);
-
-      for (int i = 4; i < 9; i++)
-	iwork(i) = 0;
-
-      rwork.resize (lrw);
-
-      for (int i = 4; i < 9; i++)
-	rwork(i) = 0;
-
       if (stop_time_set)
 	{
 	  itask = 4;



-------------------------------------------------------------
Octave is freely available under the terms of the GNU GPL.

Octave's home on the web:  http://www.octave.org
How to fund new projects:  http://www.octave.org/funding.html
Subscription information:  http://www.octave.org/archive.html
-------------------------------------------------------------