Path: news.mathworks.com!not-for-mail
From: <HIDDEN>
Newsgroups: comp.soft-sys.matlab
Subject: Re: Ill conditioned matrix makes linsolve crash
Date: Tue, 3 Nov 2009 09:40:06 +0000 (UTC)
Organization: ErasmusMC
Lines: 37
Message-ID: <hcotpm$7vf$1@fred.mathworks.com>
References: <hcc4ma$rso$1@fred.mathworks.com> <hcdekc$bdc$1@fred.mathworks.com> <4ca2c11d-c63e-40b8-a04f-58330c624c65@h2g2000vbd.googlegroups.com>
Reply-To: <HIDDEN>
NNTP-Posting-Host: webapp-03-blr.mathworks.com
Content-Type: text/plain; charset="ISO-8859-1"
Content-Transfer-Encoding: 8bit
X-Trace: fred.mathworks.com 1257241206 8175 172.30.248.38 (3 Nov 2009 09:40:06 GMT)
X-Complaints-To: news@mathworks.com
NNTP-Posting-Date: Tue, 3 Nov 2009 09:40:06 +0000 (UTC)
X-Newsreader: MATLAB Central Newsreader 1095751
Xref: news.mathworks.com comp.soft-sys.matlab:581990


Greg Heath <heath@alumni.brown.edu> wrote in message <4ca2c11d-c63e-40b8-a04f-58330c624c65@h2g2000vbd.googlegroups.com>...
> On Nov 2, 5:00?am, "Sebastiaan "
> <s.breedv...@erasmusmc.REMOVE.BOO.BOO.nl> wrote:
> > I am glad to be of some help :)
> >
> > This bug reminds me of something that happend in 2008a. I think it is this bug as well, but it depended on the runtime of the Matlab session.
> >
> > My work involves mathematical optimization, in which linear systems are solved hundreds of times for 1 problem. The problem was that in a long batch (~1 day) for solving many problems, Matlab crashed somewhere. However, if I restarted that single problem, Matlab did not crash.
> >
> > So the bug was reproducable for the long run, on different systems (and maybe I have even tried 2007b). However, the matrix which made Matlab crash, did not crash a fresh session.
> >
> > I fixed it by checking if the reciprocal condition is sufficient prior to solving the system.
> >
> > Sebastiaan
> >
> >
> >
> > "Bobby Cheng" <bch...@mathworks.com> wrote in message <hcf8jm$9u...@fred.mathworks.com>...
> > > I have not done this myself as I can change this from the inside. :)
> >
> > > But I think you can track the report update and comment of the content.
> > > Again, I have not tried any on this.
> >
> > > I can assure you that it is the same issue in the bug report. I am
> > > investigating the issue and have added your matrix into our tests. So thank
> > > you for the test case.
> >
> > > ---Bob
> 
> Why not try rcond, backslash and pinv ?
> 
> Greg

Interesting suggestion, I was unaware of the pseudoinverse method. I will have a look at it.

Thank you!
Sebastiaan