[Pkg-octave-devel] [OctDev] A Bug in Octave-OdePkg

[Wang Long]

On Wed, 2008-10-08 at 21:33 +0200, Thomas Treichl wrote:
> Wang Long schrieb:
> > Hi Thomas,
> > 
> > Thank you very much in helping me with this problem! The solution in
> > your email solved the problem I mentioned before, but when I tried some
> > other t_in's, for example,
> >   t_in_2=[0.00 0.10 0.23 0.38 0.63 1.21 1.97];
> >   t_in_3=[0.00 0.03 0.05 0.11 0.17 0.25 0.38 0.47 0.68 0.91 1.38 1.98];
> > it seems that the same problem comes out again in the 0.6.0 release of
> > odepkg :(  
> > 
> > I examined the improper t_out's, and found that every element in them is
> > identical to t_in's, respectively, except those at ``t_out(end-1)'',
> > which is created by ode45. Therefore, can we simply make ode45 check the
> > length of t_out, and delete certain elements of t_out (and ``y'', of
> > course) if the length of t_out is larger than t_in?
> > 
> > Thanks!
> > 
> > Regards,
> > Wang Long
> 
> Hi Wang,
> 
> there seems to be another problem in the 0.6.0 solver file(s), I can't see that 
> with the current sources. I'll send you a snapshot of the latest solver files 
> offside this mailing list in a few minutes (because of the sizes of these 
> files). Please try once again with these files...
> 
>    Thomas

Hi Thomas,

The problem was solved by the snapshot of latest version, thank you very
much!

At first, your latest snapshot of ode45, ode78 and other ode-solvers
does not work at all but complained:
   error: structure has no member `OutputSave'
   error: evaluating argument list element number 1
   error: if: error evaluating conditional expression
   error: evaluating if command near line 166, column 3
   error: called from `ode45' in file `ode45.m'

I think this is due to the mismatch between `odeset' version 0.6.0 and
the latest snapshot. Then I downloaded the latest version (0.6.4) of
odepkg released at http://octave.sf.net/odepkg/ and tried with my
t_in's, only got another error:
   Solving has not been successful. The iterative integration 
   loop exited at time t = 1.470000 before endpoint at 
   tend = 1.780000 was reached.  This may happen if the 
   stepsize grows smaller than defined in vminstepsize. Try 
   to reduce the value of "InitialStep" and/or "MaxStep" with 
   the command "odeset".

Fortunately, everything works after the ode45 and other ode-solvers in
odepkg version 0.6.4 were overwritten with your latest version. Thank
you for your continuously help!

Best wishes and regards!

Wang Long