Package: libarpack2 Version: 2.1-8 Severity: normal Tags: patch
This evening, I ran into a pretty frustrating problem with ARPACK. It aborted without being able to compute an Arnoldi factorization from within a custom Python extension, but the same snippet of code (with the same matrix!) would work just fine when executed from the command line in a plain C++ program. To make a long story short, I eventually tracked down the root cause: Both LAPACK and ARPACK define a routine called SECOND, but with different call signatures. LAPACK's copy is a function, whereas ARPACK's copy is a subroutine. Usually, all goes well, and the linker is intelligent enough to pick the right copy in all instances. I was unfortunate enough to be in a situation where that was not the case. The call to the wrong SECOND messed up the stack, and things got really strange from there. (For example, DLARNV returned a NaN instead of a proper number.) Apparently, the dynamic linker that loaded the Python module resolved the SECOND symbol in ARPACK to the LAPACK one. Hence, the ARPACK-supplied SECOND routine needs to be renamed. The attached patch (a revised version of a quick sed job) realizes this suggestion by renaming the routine to ARSCND (as in "ARpack SeCoND"), which fixed the problem for me. Apparently, somebody else on the Octave team [1] ran into a similar problem, but got only unhelpful replies. Andreas [1] http://www.octave.org/octave-lists/archive/help-octave.2004/msg01466.html -- System Information: Debian Release: testing/unstable APT prefers testing APT policy: (500, 'testing'), (99, 'unstable') Architecture: i386 (i686) Shell: /bin/sh linked to /bin/bash Kernel: Linux 2.6.11 Locale: LANG=C, LC_CTYPE=C (charmap=ANSI_X3.4-1968) Versions of packages libarpack2 depends on: ii atlas3-base [liblapack.s 3.6.0-19 Automatically Tuned Linear Algebra ii blas 1.1-14 Basic Linear Algebra Subroutines, ii lapack3 [liblapack.so.3] 3.0.20000531a-6 library of linear algebra routines ii libc6 2.3.2.ds1-22 GNU C Library: Shared libraries an ii refblas3 [libblas.so.3] 1.2-8 Basic Linear Algebra Subroutines 3 -- no debconf information
arpack-arscnd-2.patch.gz
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