Re: Greased Lightning: ATLAS

[David Bateman]

Miroslaw Kwasniak wrote:

> On Wed, May 18, 2005 at 06:03:26PM -0700, Keith Goodman wrote:
>  
>
> > On 5/18/05, Marius Schamschula <address@hidden> wrote:
> >    
> >
> > > Get it at:
> > >
> > > <http://math-atlas.sourceforge.net/>
> > >      
> > I installed the atlas (3.6.0-19) debian packages: atlas3-base,
> > atlas3-base-dev, and atlas3-headers.
> >
> > But I don't know how to check if Octave is using them.
> >    
>
> On my Debian
>
> $ ldd `which octave-2.1.50`|grep las
>        liblapack.so.2 => /usr/lib/atlas/liblapack.so.2 (0x49b65000)
>        libblas.so.2 => /usr/lib/atlas/libblas.so.2 (0x4a595000)
>                                ^^^^^ 
>
> $ ldd `which octave-2.9.2`|grep las
>        liblapack.so.3 => /usr/lib/atlas/liblapack.so.3 (0x4abfb000)
>        libblas.so.3 => /usr/lib/atlas/libblas.so.3 (0x4b249000)
>        libblas.so.2 => /usr/lib/atlas/libblas.so.2 (0x4a595000)
>
>  

The important point for octave is that it finds an external version of 
lapack and blas at all at the time it is configured. The version is not 
important. The reason this is important, is that if octave doesn't find 
lapack and blas when it is configured, it will compile local versions of 
lapack and blas into the octave library libcruft. Unfortunately 
libcruft.so is found linked before the blas/lapack libraries and so, 
once that has happened to only way to use altas would be using the 
LD_PRELOAD environment variable to force it to be loaded first, which is 
an ugly solution.

Once I have a generic build of octave linked to lapack/blas of whatever 
flavor, what I do on my mandrake system, and what I presume debian does, 
is then to play with either the LD_LIBRARY_PATH environment variable or 
the /etc/ld.so.conf file to set the library search path of each and 
every different system I run on to find the correct version of ATLAS, or 
leave it with a generic LAPACK/BLAS build if there is no other choice 
(rare). So I then have a version of octave that I can build once and use 
everywhere...

D.

--
David Bateman                                address@hidden
Motorola Labs - Paris                        +33 1 69 35 48 04 (Ph) 
Parc Les Algorithmes, Commune de St Aubin    +33 1 69 35 77 01 (Fax) 
91193 Gif-Sur-Yvette FRANCE

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