Prof Brian Ripley ripley at stats.ox.ac.uk
Mon Aug 29 15:43:28 CEST 2005

On Mon, 29 Aug 2005, Göran Broström wrote:

> On Mon, Aug 29, 2005 at 11:48:23AM +0100, Prof Brian Ripley wrote:
>> On Mon, 29 Aug 2005, Göran Broström 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

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