[SciPy-dev] signbit and -inf

Travis Oliphant oliphant at ee.byu.edu
Wed Oct 19 12:53:03 CDT 2005


Darren Dale wrote:

>>I can run the full test without a segfault, although I am only using the
>>newcore (I get a segfault when I install newscipy and try to import scipy).
>>I am using Gentoo on a Pentium4, with Python-2.4.2 and gcc-3.4.4. I built
>>scipy against BLAS/LAPACK/ATLAS using the same site.cfg as I used to build
>>scipy-0.3.2. It turns out that on my machine, signbit returns False for any
>>negative number, not just -inf.
>>    
>>
>
>Does anyone have any suggestions as to how I can pursue this?
>
>  
>
Look at the config.h file in the scipy include directory  (under 
site-packages/scipy/base/include)

The code for signbit is from cephes and is in 
scipy/base/src/_signbit.c   It is pretty simple but depends on certain 
platform characteristics.

The important questions are

is WORDS_BIGENDIAN defined in pyconfig.h (in include/pythonX.X) and what 
is the SIZEOF integer on your platform.

For your system, I would expect SIZEOF_INT to be 4 (look in config.h) 
and WORDS_BIGENDIAN to not be defined. 

-Travis




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