[Numpy-discussion] Biulding Numarray with atlas.

Chris Barker Chris.Barker at noaa.gov
Thu Jul 21 15:28:14 EDT 2005

Todd Miller wrote:
> I think this is a SciPy FAQ and following their advice is how I've
> worked around it in the past myself:
> http://www.scipy.org/documentation/mailman?fn=scipy-dev/2001-November/000105.html

I'd seem that note before, and it wasn't very helpful, but then I 
noticed, in the Numeric customize.py:

  Example: Some Linux distributions have ATLAS, but not LAPACK (if you're
     liblapack file is smaller than a megabyte, this is probably you)
     Use our own f2c'd lapack libraries, but use ATLAS for BLAS.

My linux distro (FC4) has a full lapack, but it's not optimized, in 
fact, it's  slower than lapack-lite. However, I got atlas from the atlas 
site, and it doesn't come with a full lapack, which would explain the 
missing symbols. Using:

#  Using ATLAS blas in /usr/local with lapack-lite
if 1:
     use_system_lapack = 0
     use_system_blas = 1
     lapack_library_dirs = ['/usr/local/lib/atlas']
     lapack_libraries = ['cblas', 'f77blas', 'atlas', 'g2c']

It compiles, works, and is about twice as fast as using the the 
Numeric-supplied blas.

I still would like to find a full, optimized lapack for Fedora Core 4. 
On my last machine, I got about a six times speed-up using the atlas 
that came with Gentoo.

But for the moment, I'm OK.

Also, I saw something in the atlas docs about how to merge the atlas 
lapack with another full lapack, so maybe I can get that to work.

Now on to see if I can do something similar with numarray.


Christopher Barker, Ph.D.
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Chris.Barker at noaa.gov

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