[Numpy-discussion] Building numpy with OpenBLAS

Sergey Bartunov sbos.net at gmail.com
Fri Dec 14 04:17:23 EST 2012

Hi. I'm trying to build numpy (1.6.2 and master from git) with
OpenBLAS on Ubuntu server 11.10.

I succeed with this just once and performance boost was really big for
me, but unfortunately something went wrong with my application and I
had to reinstall numpy. After that I couldn't reproduce this result
and even just perform faster than default numpy installation with no
external libraries anyhow.

Now things went even worse. I assume that numpy built with BLAS and
LAPACK should do dot operation faster than "clean" installation on
relatively large matirces (say 2000 x 2000). Here I don't use OpenBLAS

I install libblas-dev and liblapack-dev by apt-get and after that
build numpy from sources / by pip (that doesn't matter for the
result). Building tool reports that BLAS and LAPACK are detected on my
system, so says "numpy.distutils.system_info" after installation. But
matrix multiplication by dot takes the same time as clean installation
(12 s vs 0.16 s with OpenBLAS). That's the first thing I'm wondering

Nevertheless I tried to compile numpy with OpenBLAS only. I have
forced this by setting ATLAS="" BLAS=/usr/lib/libopenblas.a
LAPACK=/usr/lib/libopenblas.a as I saw somewhere in the internet. I
had installed numpy exactly this way at the first time when I was
lucky. But now it doesn't work for me. I tryied installing OpenBLAS
from sources and as libopenblas-dev ubuntu package.

So how can I fix this? Many thanks in advance.

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