From ripley@stats.ox.ac.uk  Fri Nov 29 17:54:02 2002
From: ripley@stats.ox.ac.uk (Prof Brian D Ripley)
Date: Fri Nov 29 17:54:02 2002
Subject: [Rd] BLAS/Lapack for OS X
In-Reply-To: <3DE793B0.683106B7@bank-banque-canada.ca>
Message-ID: <Pine.GSO.4.44.0211291647500.6594-100000@auk.stats>

NB:  I referred to sunperf, not ATLAS.

Sunperf is a BLAS/LAPACK replacement, not just a version of BLAS.
There are problems where using an optimized BLAS helps, but my comment was
about an optimized LAPACK on top of an optimized BLAS.

On Fri, 29 Nov 2002, Paul Gilbert wrote:

> ripley@stats.ox.ac.uk wrote:
> ...
> > I have hacked the code to use sunperf and on real problems the
> > gain is negligible.
> ...
>
> I also found this to be the case in some recent testing I did in Linux
> (Mandrake 9.0) with an AMD Athlon 2100+. Converting from my non BLAS
> version of R 1.6.1 to optimized ATLAS saved about 10 minutes on a 4.5
> hour test suite. This was using a .a rather than a .so version of the
> library, but according to a comment by Doug Bates, the .a library is
> probably faster (but I presume uses more memory). The tests do many
> things I would not expect to benefit from ATLAS, but about a quarter of
> the time is spent on programs that do make fairly heavy use of La.svd
> and La.eigen. So, on some problems you might save some time, but overall
> I think, as Brian says, the gain is negligible.
>
> Paul Gilbert
>

-- 
Brian D. Ripley,                  ripley@stats.ox.ac.uk
Professor of Applied Statistics,  http://www.stats.ox.ac.uk/~ripley/
University of Oxford,             Tel:  +44 1865 272861 (self)
1 South Parks Road,                     +44 1865 272860 (secr)
Oxford OX1 3TG, UK                Fax:  +44 1865 272595



[Rd] BLAS/Lapack for OS X
Prof Brian D Ripley