[SciPy-Dev] arpack failures 64-bit

[Aric Hagberg]

On Fri, Jun 18, 2010 at 11:00 PM, Ralf Gommers
<ralf.gommers at googlemail.com> wrote:
> Arpack test failures have been reported by several people, all on 64 bit. On
> 32-bit it's fine.
>
> ======================================================================
> ERROR: test_nonsymmetric_modes (test_arpack.TestEigenNonSymmetric)
> ----------------------------------------------------------------------
> Traceback (most recent call last):
>  File
> "/sw/lib/python2.6/site-packages/scipy/sparse/linalg/eigen/arpack/tests/test_arpack.py",
> line 204, in test_nonsymmetric_modes
>    self.eval_evec(m,typ,k,which)
>  File
> "/sw/lib/python2.6/site-packages/scipy/sparse/linalg/eigen/arpack/tests/test_arpack.py",
> line 186, in eval_evec
>    eval,evec=eigen(a,k,which=which,**kwds)
>  File
> "/sw/lib/python2.6/site-packages/scipy/sparse/linalg/eigen/arpack/arpack.py",
> line 397,
> in eigen
>    params.iterate()
>  File
> "/sw/lib/python2.6/site-packages/scipy/sparse/linalg/eigen/arpack/arpack.py",
> line 222,
> in iterate
>    raise RuntimeError("Error info=%d in arpack" % self.info)
> RuntimeError: Error info=-8 in arpack
>
> For the full list of errors see
> http://article.gmane.org/gmane.comp.python.scientific.devel/13706/match=arpack
> (on OS X).
> Similar report on Linux:
> http://thread.gmane.org/gmane.comp.python.scientific.devel/8551
> This seems also related: http://projects.scipy.org/scipy/ticket/725.
>
> Does anyone have time to look at this soon? If not, can I mark them as
> knownfail for 0.8.0?

I took a quick look at this but I don't have a fix and I also can't
reproduce the problem on 64 bit Linux.

The error is coming from the LAPACK routine zlahqr
which is what the -8 error code refers to.  See error codes at
http://projects.scipy.org/scipy/browser/trunk/scipy/sparse/linalg/eigen/arpack/ARPACK/SRC/zneupd.f#L149
:

c          = -8: Error return from LAPACK eigenvalue calculation.
c                This should never happened.

(and around line 557 where the error is generated after calling zlahqr)
and the section the
http://projects.scipy.org/scipy/browser/trunk/scipy/sparse/linalg/eigen/arpack/ARPACK/SRC/zneupd.f#L557

The LAPACK subroutine zlahqr in currently included in scipy since in earlier
testing (on Linux) we found that this function as included in the
packaged libraries was producing errors.

Further, the interface to complex number functions had to be hacked
to make it work on OSX since the OSX distributed LAPACK had a different
(C, rather than Fortran) interface: http://projects.scipy.org/scipy/ticket/725

Is this an OSX issue only? Those tests pass for me on 64 bit Linux.
Perhaps we need to revisit the code David inserted (see ticket 725 above)?

$ uname -a
Linux ll 2.6.31-22-generic #60-Ubuntu SMP Thu May 27 02:41:03 UTC 2010
x86_64 GNU/Linux
$ dpkg -l |grep atlas
ii  libatlas-base-dev                    3.6.0-22ubuntu2
             Automatically Tuned Linear Algebra Software,
ii  libatlas-headers                     3.6.0-22ubuntu2
             Automatically Tuned Linear Algebra Software,
ii  libatlas3gf-base                     3.6.0-22ubuntu2
             Automatically Tuned Linear Algebra Software,
$ dpkg -l |grep -i lapack
ii  liblapack-dev                        3.2.1-1
             library of linear algebra routines 3 - stati
ii  liblapack3gf                         3.2.1-1
             library of linear algebra routines 3 - share
>>> scipy.test()
Running unit tests for scipy
NumPy version 1.4.1
NumPy is installed in /home/aric/lib/python/numpy
SciPy version 0.8.0b1
SciPy is installed in /home/aric/lib/python/scipy
Python version 2.6.4 (r264:75706, Dec  7 2009, 18:43:55) [GCC 4.4.1]
nose version 0.11.3
......................
snip
......................................................................
======================================================================
ERROR: test_decomp.test_lapack_misaligned(<function solve at
0x314c938>, (array([[  1.734e-255,   8.189e-217,   4.025e-178,
1.903e-139,   9.344e-101,
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/home/aric/lib/python/nose-0.11.3-py2.6.egg/nose/case.py",
line 186, in runTest
    self.test(*self.arg)
  File "/home/aric/lib/python/scipy/linalg/tests/test_decomp.py", line
1071, in check_lapack_misaligned
    func(*a,**kwargs)
  File "/home/aric/lib/python/scipy/linalg/basic.py", line 49, in solve
    a1, b1 = map(asarray_chkfinite,(a,b))
  File "/home/aric/lib/python/numpy/lib/function_base.py", line 586,
in asarray_chkfinite
    raise ValueError, "array must not contain infs or NaNs"
ValueError: array must not contain infs or NaNs

----------------------------------------------------------------------
Ran 4420 tests in 54.254s

FAILED (KNOWNFAIL=11, SKIP=32, errors=1)
<nose.result.TextTestResult run=4420 errors=1 failures=0>


Aric