[Numpy-discussion] Numpy installation problem

[Jonathan Tu]

On Jul 24, 2010, at 4:04 PM, Keith Goodman wrote:

> On Sat, Jul 24, 2010 at 12:58 PM, David Cournapeau <cournape at gmail.com> wrote:
>> On Sun, Jul 25, 2010 at 4:50 AM, Jonathan Tu <jhtu at princeton.edu> wrote:
>> 
>>> I am unable to find the files lapack_lite.so or _dotblas.so.  I used the locate command to look for them.
>> 
>> If you just installed numpy, locate won't find them as locate uses a
>> database which is usually updated once in a while.
>> 
>> Depending on how you installed numpy, you will find lapack_lite.so in
>> /usr, $HOME/.local or somewhere else (and also in the build directory
>> in the numpy source tree).
> 
> Here's one way to find where numpy is installed:
> 
> $ python
>>>> import numpy
>>>> numpy
> <module 'numpy' from
> '/usr/local/lib/python2.6/site-packages/numpy/__init__.pyc'>
> 
> So on my computer numpy is installed in /usr/local/lib/python2.6/site-packages
> 
>> _dotblas.so may not be present, but numpy cannot work without a lapack_lite.so.

Thanks for the tip!  This worked, and much faster than the manual hunting through directories I'd been trying.  Upon running ldd on lapack_lite.so and on _dotblas.so, I got the following (first for lapack_lite, then for _dotblas):

	libpthread.so.0 => /lib64/tls/libpthread.so.0 (0x0000002a95792000)
	libc.so.6 => /lib64/tls/libc.so.6 (0x0000002a958a7000)
	/lib64/ld-linux-x86-64.so.2 (0x000000552aaaa000)

	libpthread.so.0 => /lib64/tls/libpthread.so.0 (0x0000002a95d36000)
	libc.so.6 => /lib64/tls/libc.so.6 (0x0000002a95e4c000)
	/lib64/ld-linux-x86-64.so.2 (0x000000552aaaa000)

I am interested in whether my Numpy installation is in fact taking advantage of the LAPACK libraries that are installed on the cluster where I'm running.  I know that Numpy can function without such an installation, but I think it is probably faster when taking advantage of optimized libraries.  In any case, I know ldd shows library dependencies, but I'm not sure how to make sense of its output, and whether or not it answers my question.




Jonathan Tu