Numpy and Scipy and their Lapack and Atlas dependencies

Question

I'm trying to install python numpy from source with libraries Lapack and Atlas. I have realized that Atlas itself contains lapack library. However if I compile it(atlas only), it has 0.5 MB. When Netlib Lapack is deployed than the library liblapac.a has more than 13 MB. This leads me to following questions:

Questions regarding numpy/scipy:

1. can i install numpy/scipy only with netlib's Lapack, or only with Atlas lib?
2. (if answer for 1 is yes) if only Atlas lib is installed (no netlib's Lapack) -are there any disadvantages (performance, functions unavailable,...)
3. is there any performance review how numpy/scipy are doing w/out Lapack/Atlas installed?
4. Numpy, or Scipy does use more Atlas/Lapack? is there any significant difference?

thanks!

Answer 1

ATLAS is not a full LAPACK implementation. It only provides a few routines that are optimized. This ATLAS page explains how to build full LAPACK that also uses ATLAS.

From the page:

ATLAS natively provides only a relative handful of the routines which comprise LAPACK.

The SciPy Homepage tells you that you need LAPACK for SciPy, but not for numpy:

Before building, you will also need to install packages that NumPy and SciPy depend on

• BLAS and LAPACK libraries (optional but strongly recommended for NumPy, required for SciPy): typically ATLAS + LAPACK, or MKL, or ACML

[...]

To summarize, if you want SciPy, you need LAPACK. If you want a faster LAPACK, you might want to install ATLAS, too. If you only want numpy, LAPACK is not required, but considered a good idea by the SciPy people.