[Numpy-discussion] debian floating point exceptions/numpy/f2py -- sse

David Cournapeau david at ar.media.kyoto-u.ac.jp
Fri Jul 14 04:31:44 CDT 2006

Andrew Jaffe wrote:
> Hi All,
> I have just switched from RHEL to debian, and all of a sudden I started 
> getting floating point exception errors in various contexts.
> Apparently, this has to do with some faulty error stuff in glibc, 
> specifically related to the sse. I would prefer to fix the actual 
> problem, but I can't seem to be able to get the recommended 'apt-get 
> source glibc' incantation to work (I'm not root, but I can sudo.)
What does not work ? The apt-get source part ? The actual building ?

Basically, if the sources are OK, you just need to do
 - fakeroot dpkg-source -x name_of_dsc_file
 - cd name_of_package
 - fakeroot dpkg-buildpackage

And that's it
> I was able to fix some of these issues by simply downgrading ATLAS to 
> not use sse instructions anymore.
> But f2py still links with sse and sse2 by default. I can't quite 
> understand the configuration well enough to work out how to turn it off. 
> Can someone give me any guidance?
The way it is supposed to work, at least on debian and ubuntu, is that 
you never link to the sse/sse2 versions, but to the non-optimized 
versions. After, the dynamic loader will get the right one (ie optimized 
if available) instead of the one linked (this of course only works for 
dynamic linking). You can check which library is picked with a ldconfig 
- p | grep lapack (for lapack functions, and so on...)


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