I install Numpy (in a virtualenv env) with OpenBlas (from the system).
$ sudo apt-get install libopenblas-dev
(env)$ mkdir evn/download
(env)$ pip install -d env/download numpy
(env)$ mkdir env/build
(env)$ cd env/build
(env)$ tar xzf ../download/numpy-1.9.2.tar.gz
(env)$ cd numpy-1.9.2
Edit the site.cfg:
[atlas]
atlas_libs = openblas
libraries = openblas
[openblas]
libraries = openblas
library_dirs = /usr/lib/openblas-base/
And then, install numpy using pip. Additionally, install numpy via system (with blas). I test the times with this scrpit. In both case, I have the same time. I check, and the system use Blas and the virtualenv use OpenBlas. Why it takes the same time?
I use Debian testing, and python 2.7.9