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
1 Dear all,
2
3 I recently submitted a question to the R-help mailing list, because I
4 noticed that matrix multiplication was giving me trouble (basically, that
5 there were some times when a result was NaN):
6 http://tolstoy.newcastle.edu.au/R/e15/help/11/09/7165.html
7
8
9 As it is mentioned in the end of the thread, the solution was to recompile
10 R against the reference blas and lapack libraries, and avoid the atlas
11 that I was using.
12
13 So it seems that the problem is not R-related, but atlas-related, and
14 linked to gentoo, I would like to share the problem with you, just in case
15 somebody has any clue on what is wrong with atlas.
16
17 Although I have firstly used a very aggressive cflags to compile atlas
18 (-Ofast), I suspected that the problem was that, but I recompiled atlas
19 using -O2 and the problem still presists with atlas, but is solved with
20 reference.
21
22 I am using atlas-3.9.23-r4, R-2.13.1 and gcc-4.6.1
23
24 Thank you,
25
26 --
27 - Xavier -

Replies

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