From bug-request at octave dot org Sun Dec 19 12:08:10 2004
Subject: Re: rank problem
From: Geraint Paul Bevan <g dot bevan at mech dot gla dot ac dot uk>
To: Andrea <agaleazzi at aliceposta dot it>
CC: bug-octave at bevo dot che dot wisc dot edu
Date: Sun, 19 Dec 2004 18:21:21 +0000

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Andrea wrote:

| Description:
| -----------
|
|   * I've got a problem to calculate the rank and the pseudoinverse of a
| matrix. In particular when I try, i.e., to calculate the rank of a
| square random matrix sometimes the system seems to be in loop and other
| times answers me with a zero
|


| Configuration (please do not edit this section):
| -----------------------------------------------
|
| uname output:     Linux localhost.localdomain 2.6.9-1.681_FC3 #1 Thu Nov
| C compiler:       gcc, version 3.4.2 20041006 (Red Hat 3.4.2-5)

The rank of a matrix is calculated using singular value decomposition
which is performed using the LAPACK library.

There have been some reports on the lists that Fedora Core 3 (which you
appear to be using) ships with a broken LAPACK library, e.g:
http://www.octave.org/octave-lists/archive/octave-maintainers.2004/msg00817.html

Perhaps your problem is related to this?

- --
Geraint Bevan
http://homepage.ntlworld.com/geraint.bevan

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