From ripley at stats.ox.ac.uk  Mon Aug 29 12:48:23 2005
From: ripley at stats.ox.ac.uk (Prof Brian Ripley)
Date: Mon, 29 Aug 2005 11:48:23 +0100 (BST)
Subject: [Rd] xerbla called from BLAS routine (PR#8100)
In-Reply-To: <20050829103457.GB14693@stat.umu.se>
References: <20050829080600.3854E13F8E@slim.kubism.ku.dk>
	<20050829091908.GA14693@stat.umu.se>
	<Pine.LNX.4.61.0508291022120.30101@gannet.stats>
	<20050829103457.GB14693@stat.umu.se>
Message-ID: <Pine.LNX.4.61.0508291145200.3755@gannet.stats>

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

> On Mon, Aug 29, 2005 at 10:27:24AM +0100, Prof Brian Ripley wrote:
>> On Mon, 29 Aug 2005, G?ran Brostr?m wrote:
> [...]
>>>
>>> BTW, the original BLAS xerbla (from the netlib page you referred to)
>>> gives the message:
>>>
>>>    WRITE( *, FMT = 9999 )SRNAME, INFO
>>> 9999 FORMAT( ' ** On entry to ', A6, ' parameter number ', I2, ' had ',
>>>    $      'an illegal value' )
>>>
>>> which I think is even better than my original suggestion.
>>> (Why was it changed?)
>>
>> Probably because R is not a Fortran program and so needs to make clear
>> what these refer to, and because LAPACK does have other error values that
>> invalid parameter values.
>
> 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.

-- 
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] xerbla called from BLAS routine (PR#8100)
Prof Brian Ripley