From albrecht.gebhardt@uni-klu.ac.at  Mon Jun  5 11:25:10 2000
From: albrecht.gebhardt@uni-klu.ac.at (Albrecht Gebhardt)
Date: Mon, 5 Jun 2000 12:25:10 +0200 (MET DST)
Subject: [Rd] make check on DU4 with R-1.1.0 snapshot
In-Reply-To: <Pine.GSO.4.05.10006030612260.5027-100000@auk.stats>
Message-ID: <Pine.OSF.4.21.0006051216460.25005-100000@zidsrv.sci.uni-klu.ac.at>

On Sat, 3 Jun 2000, Prof Brian D Ripley wrote:

> On Fri, 2 Jun 2000, Albrecht Gebhardt wrote:
> 
> > On Fri, 2 Jun 2000, Albrecht Gebhardt wrote:
> > 
> > > On Fri, 2 Jun 2000, Albrecht Gebhardt wrote:
> > > 
> > > > 
> > > > I just tried the rsync version of R-1.1.0 on one of my alphas:
> > > > It compiles without problems (gcc/g77 2.95.2, system is DU4.0E)
> > > > .........
> > > > 
> > > > I compiled --whithout-dxml, so I'm not using any special numeric library.
> > > > 
> > > 
> > > Sorry I mixed something up in my report: In this compile I used the alpha
> > > specific DXML library, in my rpms I omit it with --without-dxml (because
> > > it sometimes crashes). I will try once more now without dxml, may be this
> > > changes something, don't know if it gets used at all in the svd code.
> > > 
> > 
> > That was the reason. Now without DXML I pass the test without modifying
> > Eps:
> 
> Nevertheless, the tolerance was too low. Most machines (e.g. Linux, 
> Solaris and Windows) are giving errors of 8 or 9 times the 
> machine precision, and with dxml you got 10x (and this failed as
> Eps was exactly 10x). eigen's help page has tolerances of 60x and 1000x,
> and I've given svd's 100x.
> 
> [...]
> 
> > So may be it is better do disable dxml support by default in ./configure?
> 
> Well, what does dxml support do for you?  Making the errors 1x machine
> precision larger than without is hardly critical.  On the other hand, I am
> not convinced that these optimized blas operations are worthwhile for all
> but the most unusual uses of R.

I did not make any performance analysis for dxml, of course it should be
better than plain BLAS or LAPACK. But I have it disabled in my setups for
long now, because I ran frequently into troubles with special LAPACK
routines. I remember the case where I used DSYEVX (selected symmetric
eigenvalues/vectors) in one of my development libraries and got
reproducable crashes, if R was linked with dxml, it was fine without. It
even crashed when I downloaded the dsyevx source from netlib and put it
into my library, R still jumped into DSYEVX from dxml and crashed. 

I guess I could gain much more performance if I could revert from using
gcc/g77 back to DEC cc/f77, but this seems impossible or at least very
difficult (R-1.1.0 compiles with DEC cc/f77 but has problems loading
libjpeg when accessing the X11 code, and crashes with memory allocation
problems in make check if called with --gui=none)


Albrecht


> -- 
> 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
> 
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.....................................................................
| Albrecht Gebhardt          Tel.: (++43 463) 2700/832               |
| Institut fuer Mathematik   Fax : (++43 463) 2700/834               |
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[Rd] make check on DU4 with R-1.1.0 snapshot
Albrecht Gebhardt