From help-octave-request at bevo dot che dot wisc dot edu  Fri Feb  4 18:43:35 2000
Subject: Re: ATLAS and octave
From: "John W. Eaton" <jwe at bevo dot che dot wisc dot edu>
To: "Timothy H. Keitt" <keitt at nceas dot ucsb dot edu>
Cc: R Clint Whaley <rwhaley at cs dot utk dot edu>, atlas@cs.utk.edu,         help-octave@bevo.che.wisc.edu
Date: Fri, 4 Feb 2000 18:44:18 -0600 (CST)

On  4-Feb-2000, Timothy H. Keitt <keitt at nceas dot ucsb dot edu> wrote:

| Sounds good to me.

Yes, I am also interested in this.  The last time I checked up on
atlas, I thought it looked promising, but it was not really ready.
But if it supports all of the level 1 and 2 blas plus some lapack
calls, then it might be time to consider replacing what we can with
atlas-generated code.

| (I'm
| assuming here that the octave's blas and lapack routines are the
| same as the standard ones, so no recoding would be necessary.)

Octave uses the Fortran blas and lapack straight from netlib.  I think
the only change is to modify xerbla so that it doesn't exit on errors.

| I've actually never quite understood why octave includes blas and lapack
| code.  It seems to defeat the purpose of having standard (and
| tunable) external libraries.  (At best it duplicates some code; at
| worst its an unofficial code fork.)

There are at least a few reasons that make sense to me.

First, there are licensing issues.  If the tuned blas libraries are
distributed under terms that are not compatible with the GPL, then
we can't distribute a version of Octave that is linked with them.

Second, it is easier to just distribute the Fortran sources than to
try to figure out if the blas and lapack libraries that are installed
on a system are the right version, or if they will even work.  If
someone reports a problem with Octave that involves the blas or lapack
routines, it is harder to debug if the problem might be due to some
broken installation of the blas or lapack.

It is also easier for people to install Octave if the instructions are
essentially `unpack a single tar file, then run configure and make',
instead of `get several packages, try to figure out how to install the
other packages (last I checked, the blas and lapack did not use
configure) and then try to build Octave using them'.

If atlas is distributed under terms that are compatible with the GPL
(I think it was the last time I checked) then I think it could be the
best solution for Octave, since there won't be any licensing problems,
and it will not require tweaking the configure script for each new
vendor blas.

jwe



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