[Octave-bug-tracker] Re: [bug #31479] Crash & bugs in eigs

[John W. Eaton]

Please use the bug tracker to post updates and additional comments for
bug reports so that people who look at the report later will have all
the info about the bug.

If there is still a problem, please open a new report.  I think the
original problem of the crash is now fixed.

Thanks,

jwe


On 31-Jan-2011, Marco Caliari wrote:

| On Fri, 28 Jan 2011, John W. Eaton wrote:
| 
| >
| > Follow-up Comment #11, bug #31479 (project octave):
| >
| > I also started a discussion about this topic on the maintainers list, which
| > is archived starting here:
| >
| > 
https://mailman.cae.wisc.edu/pipermail/octave-maintainers/2011-January/022538.html
| >
| > Rik, in the debian package, it looks like they compile with -O3 but no other
| > special options.  I doubt there would be too much of a difference between 
that
| > and the default -O2 when using gfortran, but I haven't tried to do any
| > testing.  ARPACK already uses the BLAS and LAPACK for linear algebra, so 
what
| > is used for that will probably have more of an effect than the compiler
| > options for ARPACK itself.
| >
| > In any case, the response so far has been to include ARPACK in Octave, so
| > I'll go ahead with that.
| >
| > Note that the patch from David does not solve the problem of sometimes
| > getting different results.  But as Rik has pointed out, "The ARPACK library 
is
| > an iterative method and it's results are absolutely going to depend on where
| > in the solution space the search begins".
| >
| > Marco, do you always get the exact same value when you use eigs(A,1), or is
| > it sometimes a complex value?  If it is sometimes complex, then I think you
| > really should be getting a complex pair.
| 
| Sorry for my delay. No, I get either a real number or a *single* complex 
| value. I'm speaking of Octave 3.3.53 and ARPACK with David's patch.
| 
| About different results at each call: in normest.m we 
| the random generator is reinitialized with rand("state",trace(A))
| in order to have a consistent results. Can't we do the same with eigs?
| 
| Cheers,
| 
| Marco
| 
| >
| >    _______________________________________________________
| >
| > Reply to this item at:
| >
| >  <http://savannah.gnu.org/bugs/?31479>
| >
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