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Re: Good eigenvalue/eigenvector test problems for eigs?
From: |
David Bateman |
Subject: |
Re: Good eigenvalue/eigenvector test problems for eigs? |
Date: |
Sat, 23 Sep 2006 15:28:31 +0200 |
User-agent: |
Thunderbird 1.5.0.5 (X11/20060817) |
Quentin Spencer wrote:
>
> On Fedora, running plain atlas (no sse or sse2) I get:
> Max error: 8.60406e-21
>
> Come to think of it, I think the eig function that is shipped in both
> the Debian and Fedora atlas packages is taken straight out of lapack
> because it's not provided directly by atlas. So, I think you're using
> the same eig function with or without atlas installed.
>
> -Quentin
>
Ok. However, its only partly true that I'm using the same eig function.
The lapack [dz]geev used by the octave eig functions states that it uses
the following external subroutines.
* ..
* .. External Subroutines ..
EXTERNAL DGEBAK, DGEBAL, DGEHRD, DHSEQR, DLACPY, DLARTG,
$ DLASCL, DORGHR, DROT, DSCAL, DTREVC, XERBLA
There are certainly a few of those that are accelerated in atlas. My
sysadmin also installed an unstable version of atlas and so there might
be something there causing the problem as well. I seem to be using
version 3.7.11 of atlas..
Regards
David
Re: Good eigenvalue/eigenvector test problems for eigs?, Sebastien Loisel, 2006/09/22