Gentoo Archives: gentoo-science

From: "Xavier Fernández i Marín" <xfim.ll@×××××.com>
To: gentoo-science@l.g.o
Subject: [gentoo-science] Atlas giving wrong results on matrix multiplication
Date: Wed, 14 Sep 2011 08:50:18
Message-Id: 20110914084814.GH2225@deu.xfim
Dear all,

I recently submitted a question to the R-help mailing list, because I
noticed that matrix multiplication was giving me trouble (basically, that
there were some times when a result was NaN):

As it is mentioned in the end of the thread, the solution was to recompile
R against the reference blas and lapack libraries, and avoid the atlas
that I was using.

So it seems that the problem is not R-related, but atlas-related, and
linked to gentoo, I would like to share the problem with you, just in case
somebody has any clue on what is wrong with atlas.

Although I have firstly used a very aggressive cflags to compile atlas
(-Ofast), I suspected that the problem was that, but I recompiled atlas
using -O2 and the problem still presists with atlas, but is solved with

I am using atlas-3.9.23-r4, R-2.13.1 and gcc-4.6.1

Thank you,

-  Xavier  -


Subject Author
Re: [gentoo-science] Atlas giving wrong results on matrix multiplication Andrea Arteaga <andyspiros@×××××.com>