bugGNU Octave - Bugs: bug #45651, Crash when inverting matrices...

 
 

bug #45651: Crash when inverting matrices sized 10x10 or bigger

Submitted by:  None
Submitted on:  Wed 29 Jul 2015 06:58:17 PM UTC  
 
Category: Octave FunctionSeverity: 3 - Normal
Priority: 5 - NormalItem Group: Segfault, Bus Error, etc.
Status: Need InfoAssigned to: None
Originator Name: Originator Email: -unavailable-
Open/Closed: ClosedRelease: 3.8.2
Operating System: GNU/Linux

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Mon 17 Aug 2015 02:26:45 PM UTC, comment #6:

Another solutions seems to be to use apt-pinning to upgrade octave to debian "testing" (I really begin to hate 'stable'). Meaning octave 4.0.0.

ukuvbu oibws <xyzdragon>
Wed 29 Jul 2015 10:20:44 PM UTC, comment #5:

Good that it was sorted out. Maybe Yade is easy to build from source and you can rebuild it against your installed libblas3.

Rik <rik5>
Project Administrator
Wed 29 Jul 2015 08:54:04 PM UTC, comment #4:

Thanks to your suggestions I tested
dpkg -l 'blas'
ii libblas-common 1.2.20110419-10 amd64
ii libblas-dev 1.2.20110419-10 amd64
ii libblas3 1.2.20110419-10 amd64
ii libopenblas-base 0.2.12-1 amd64
ii libopenblas-dev 0.2.12-1 amd64

After
sudo apt-get purge libopenblas-base
it seems to work now.
The problem is, that purging openblas also purged Yade (because it is a dependency of libyade) which I need, but I guess this is a problem for the openblas or yade bug list :(

ukuvbu oibws <xyzdragon>
Wed 29 Jul 2015 08:19:18 PM UTC, comment #3:

Version 3.8.2 is unsupported. Unless the behavior can be reproduced in 4.0.0 we will need to close this bug. The symptoms, however, point away from Octave and towards whatever BLAS or LAPACK library is installed.

Rik <rik5>
Project Administrator
Wed 29 Jul 2015 07:53:44 PM UTC, comment #2:

It appears that you should move up to the current release,
which is 4.0

After minor corrections all the operations with A and B size 12x12
work as expected.

However, they also work under 3.8.2, so there could
be a problem with your installation.

Michael Godfrey <godfrey>
Project Member
Wed 29 Jul 2015 07:36:08 PM UTC, comment #1:

I can not confirm this, neither with 3.8.2 nor with 4.0.0

Markus Bergholz <markuman>
Wed 29 Jul 2015 06:58:17 PM UTC, original submission:

octave --version
GNU Octave, version 3.8.2
[...]
Octave was configured for "x86_64-pc-linux-gnu"

%N=11;
N=12;
A=zeros(N);
for n=2:N-1
A(n,n-1)= 1;
A(n,n )=-2;
A(n,n+1)= 1;
end
A=A(2:end-1,2:end-1);
disp(A);
inv(A);

"Segmentation fault"

This only happens for N=12, not N=11 or less (I cut off the first and last row and column therefore the actual matrix is N-2xN-2 big). I guess it switches to some other method of calculation.

The same happens if I use backslash:
B=zeros(N);
for n=1:N
B(n,n)=1
end
AB

"Segmentation fault"

It doesn't happen for inv(B) though... Or in general it doesn't seem to hapen for diagonal matrices.

Temporary measure: implement a function mat_inv using a Gauss-Jordan algorithm myself. (very slow!)

Anonymous

 

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  • -unavailable- added by xyzdragon (Posted a comment)
  • -unavailable- added by rik5 (Posted a comment)
  • -unavailable- added by godfrey (Posted a comment)
  • -unavailable- added by markuman (Posted a comment)
  • -unavailable- added by None (Submitted the item)
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    Follow 2 latest changes.

    Date Changed By Updated Field Previous Value => Replaced By
    Wed 29 Jul 2015 10:20:44 PM UTCrik5Open/ClosedOpen=>Closed
    Wed 29 Jul 2015 08:19:18 PM UTCrik5StatusNone=>Need Info

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