[SciPy-user] BLAS and srotgm

Robert Kern robert.kern@gmail....
Fri Sep 14 11:00:27 CDT 2007

Donna Calhoun wrote:
> Robert Kern <robert.kern <at> gmail.com> writes:
> ----------------------------------------------------------------------------
>>> .............(lots cut out here)..........................
>>>> line 14, in <module>
>>>>      from scipy.linalg import fblas
>>>> ImportError: 
>>>> /usr/local/Python-2.5-with_tk/lib/python2.5/site-packages/scipy/linalg/
>>> fblas.so: 
>>>> undefined symbol: srotmg_
>>>> ----------------------------------------------------------------------------
>> Can you give us the contents of your site.cfg, the locations of all of the
>> libblas's on your system, the output from your build, and the g77 command that
>> worked? That might help us to explain the problem at least, if not fix it.
> Yes, here is the short answer to your question.  Here is the offending g77
> command : 
> # Original command :
> long_dir  = build/temp.linux-i686-2.5/build/src.linux-i686-2.5
> g77 -shared -L/usr/lib -lutil -lc -lpthread -L/usr/local/tk/lib -ltk8.4
> -L/usr/local/tcl/lib -ltcl8.4
> $long_dir/build/src.linux-i686-2.5/Lib/lib/blas/fblasmodule.o
> $long_dir/fortranobject.o
> $long_dir/Lib/lib/blas/fblaswrap.o
> $long_dir/build/src.linux-i686-2.5/Lib/lib/blas/fblas-f2pywrappers.o
> -L/usr/local/lapack-3.1.1 -L/usr/local/Python-2.5-with_tk/lib
> -L/usr/local/Python-2.5-with_tk/lib/python2.5/lib-dynload
> -Lbuild/temp.linux-i686-2.5 -lblas -lblas -lpython2.5 -lz -lg2c -o
> build/lib.linux-i686-2.5/scipy/lib/blas/fblas.so
> I have several 'libblas' on my system (and most of them are old)
> /usr/lib/libblas.a
> /usr/lib/libblas.so
> /usr/lib/libblas.so.3
> /usr/lib/libblas.so.3.0
> /usr/lib/libblas.so.3.0.3
> /usr/local/lapack-3.1.1/libblas.a
> /usr/local/lapack-3.1.1/libblas.so
> and the scipy build found the first one.  This is first in the g77 command, and
> so g77 quit looking for any other libraries.  That library didn't have 
> 'srotmg' in it.    (As to WHY I had libc, etc in my link path, that will have
> to wait for a longer post!)  
> I removed the library flags to libc, and libutil and the build picked up the
> correct blas library. 

I'm curious as to why you had -L/usr/lib in there. Did it come from Python's
build or do you have an LDFLAGS environment variable sitting around that's

Robert Kern

"I have come to believe that the whole world is an enigma, a harmless enigma
 that is made terrible by our own mad attempt to interpret it as though it had
 an underlying truth."
  -- Umberto Eco

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