[Numpy-discussion] Building Numeric with a native blas ?

Gerard Vermeulen gerard.vermeulen at grenoble.cnrs.fr
Fri Jul 30 10:01:34 CDT 2004

On Fri, 30 Jul 2004 09:28:35 -0700
"Chris Barker" <Chris.Barker at noaa.gov> wrote:

> David M. Cooke wrote:
> > Atlas might have installed a liblapack, with the (few) functions that it
> > overrides with faster ones. It's by no means a complete LAPACK
> > installation. Have a look at the difference in library sizes; a full
> > LAPACK is a few megs; Atlas's routines are a few hundred K.
> OK, I'm really confused now. I got it working, but it seems to have 
> virtually identical performance to the Numeric-supplied lapack-lite.
> I'm guessing that the LAPACK package I emerged does NOT use the atlas BLAS.
> if the atlas liblapack doesn't have all of lapack, how in the world are 
> you supposed to use it? I have no idea how I would get the linker to get 
> what it can from the atlas lapack, and the rest from another one.
> Has anyone done this on Gentoo? If not how about another linux distro, I 
> don't have to use portage for this after all.
I am making my own ATLAS rpms and basically I am doing the following
(starting from the ATLAS source directory, with the LAPACK unpacked
 inside it):

# build lapack
# Note added right now: this assumes that the LAPACK/make.inc has been patched
(cd LAPACK; make lapacklib)

# configuration: leave the blank lines in the 'here' document
# Note added right now: this is dependent on your CPU architecture
if  [ $(hostname)=="zombie" ] ; then
make config <<EOF



# build atlas
make install arch=Linux_P4SSE2_2

# make an atlas enhanced lapack library
# Note added right now: this is explained in the ATLAS (or SciPy docs)
cd lib/Linux_P4SSE2_2
mkdir tmp
cd tmp
ar x ../liblapack.a
cp ../../../LAPACK/lapack.a ../liblapack.a
ar r ../liblapack.a *.o
cd ..
rm -rf tmp


That is all -- Gerard

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