From ripley at stats.ox.ac.uk  Mon Aug 29 15:43:28 2005
From: ripley at stats.ox.ac.uk (Prof Brian Ripley)
Date: Mon, 29 Aug 2005 14:43:28 +0100 (BST)
Subject: [Rd] BLAS and ATLAS
In-Reply-To: <20050829133409.GB3471@stat.umu.se>
References: <20050829133409.GB3471@stat.umu.se>
Message-ID: <Pine.LNX.4.61.0508291442001.5510@gannet.stats>

On Mon, 29 Aug 2005, G?ran Brostr?m wrote:

> On Mon, Aug 29, 2005 at 11:48:23AM +0100, Prof Brian Ripley wrote:
>> On Mon, 29 Aug 2005, G?ran Brostr?m wrote:
>
>>> LAPACK/BLAS routines call xerbla "if an input parameter has an
>>> invalid value" (exact quote from  XERBLA at Netlib). Other types of errors
>>> are not printed (by xerbla), but it is up to the user to check the return
>>> value of the argument 'INFO'. See
>>> http://www.netlib.org/lapack/lug/node119.html.
>>
>> Maybe, that is not actually true for real-life LAPACK implementations, as
>> I did say.
>>
>>> So we can safely give the more informative, original, error messages,
>>> together with mentioning LAPACK and eventually BLAS, whatever you prefer.
>>> This would "make clear what these refer to". Given that other BLAS/LAPACK
>>> routines than xerbla aren't changed in R, of course.
>>
>> Irrelevant as R is often compiled against other ones implementations.
>
> That confuses me. My R installation (R-devel of yesterday) is compiled
> against ATLAS BLAS (from Debian-unstable). Why, then, is xerbla from  R
> sources used anyway?

Because it is the only one seen: ATLAS does not provide it.  There is no 
guarantee that ATLAS or libsunperf or vecLib ... only use xerbla in the 
meaning in that page.

-- 
Brian D. Ripley,                  ripley at 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 272866 (PA)
Oxford OX1 3TG, UK                Fax:  +44 1865 272595


[Rd] BLAS and ATLAS
Prof Brian Ripley