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


From: Rik
Subject: [Octave-bug-tracker] [bug #31479] Crash & bugs in eigs
Date: Fri, 29 Oct 2010 01:44:02 +0000
User-agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.2.11) Gecko/20101013 Ubuntu/9.10 (karmic) Firefox/3.6.11

Follow-up Comment #2, bug #31479 (project octave):

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.  There may
be an opportunity to initialize the starting point based on some
characteristic of the initial matrix which yields better convergence, but I'm
not sure what that would be.

As an aside, you want to use the right tool for the job and eigs is not the
right tool for a small matrix.  You can just use eig and it will be more
computationally efficient and deliver all of the eigenvalues, not just one as
you were requesting.

Finally, I can confirm the a memory leak and crash in the eigs code. 
Attached is a small script which runs eigs repeatedly and always causes a
crash on my system.

According to the backtrace from run-octave, the problem is in the destructor
for the Array class.


#4  0x0000003e8407ac6c in *__GI___libc_free (mem=<value optimized out>) at
malloc.c:3716
#5  0x00007ffff73cb72d in Array<double>::~Array() () from
/home/rik/wip/Projects_Mine/octave-doc/src/.libs/liboctinterp-3.3.53+.so
#6  0x00007ffff29393d8 in int
EigsRealNonSymmetricMatrix<SparseMatrix>(SparseMatrix const&, std::string,
int, int, int&, ComplexMatrix&, ComplexColumnVector&, SparseMatrix const&,
ColumnVector&, ColumnVector&, std::ostream&, double, bool, bool, int, int) ()
   from /home/rik/wip/Projects_Mine/octave-doc/src/DLD-FUNCTIONS/eigs.oct
#7  0x00007ffff2921e07 in Feigs(octave_value_list const&, int) () from
/home/rik/wip/Projects_Mine/octave-doc/src/DLD-FUNCTIONS/eigs.oct


(file #21855)
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Additional Item Attachment:

File name: force_eigs_crash.m             Size:0 KB


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