From simon.urbanek at r-project.org  Wed Mar  6 05:46:05 2013
From: simon.urbanek at r-project.org (Simon Urbanek)
Date: Tue, 5 Mar 2013 23:46:05 -0500
Subject: [Rd] crossprod(): g77 versus gfortran
In-Reply-To: <5136BA23.6010605@gmail.com>
References: <51358CA9.4030004@stats.ox.ac.uk> <5136BA23.6010605@gmail.com>
Message-ID: <6B13B887-BA0A-4CDC-8377-96A7BD140228@r-project.org>


On Mar 5, 2013, at 10:38 PM, Benjamin Tyner wrote:

> Thank you Brian. So it sounds like appendix B.6 of
> 
>   http://cran.r-project.org/doc/manuals/R-admin.html
> 
> should be updated to reflect that g77 is no longer supported; I will
> notify CRAN at R-project.org of this unless you suggest a different recipient.
> 

I think you misunderstood - you can use g77 but you will also need F90-capable Fortran - typically gfortran - unless you have other source for LAPACK and that's what B.6 says explicitly.

Cheers,
Simon




> In any case, I tried again but using gfortran version 4.4.0, and now the
> timings are back to what they were under g77.
> 
> As for BLAS, was using the one that ships with R, as wanted to keep
> things simple for benchmarking purposes.
> 
> Thanks again.
> 
>> On 05/03/2013 01:45, Benjamin Tyner wrote:
>>> / Hi
>> />/
>> />/ I've got two builds of R, one using g77 (version 3.4.6) and the other
>> />/ using gfortran (version 4.1.2). The two builds are otherwise identical
>> />/ as far as I can tell. The one which used g77 performs crossprod()s
>> />/ roughly twice as fast as the gfortran one. I'm wondering if this rings a
>> />/ bell with anyone, and if so, are you aware of any configure settings
>> />/ which will improve the performance when using gfortran. This is on RHEL 5.
>> /
>> Note that recent versions of R do not build with g77, and have 
>> performance improvements in linear algebra.  So please follow the 
>> posting guide and give up the 'at a minimum' information requested and a 
>> reproducible example.
>> 
>> Also, check what BLAS is in use: an optimized BLAS can make a lot of 
>> difference on such simple operations.
>> 
>> 
>> -- 
>> Brian D. Ripley,                  ripley at stats.ox.ac.uk <https://stat.ethz.ch/mailman/listinfo/r-devel>
>> Professor of Applied Statistics,  http://www.stats.ox.ac.uk/~ripley/ <http://www.stats.ox.ac.uk/%7Eripley/>
>> 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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[Rd] crossprod(): g77 versus gfortran
Simon Urbanek