From help-request at octave dot org Sat Jul 31 22:09:03 2004 Subject: Re: error: `eig' undefined near line 5 column 7 From: "Henry F. Mollet" To: Rich Shepard , Octave_post Date: Sat, 31 Jul 2004 20:05:34 -0700 Others have replied and resolved emacs problems. Here are the eight solutions (eigenvalues) to your matrix and I suggest that it is not a symmetric matrix as can be seen by inspection. In addition, all eigenvalues would be real for a symmetric matrix. It looks as if your matrix is inverse symmetric, but I'm not familiar with such terminology. Henry A = 1.00000 0.14300 0.33300 9.00000 0.16700 0.20000 0.50000 0.25000 7.00000 1.00000 0.20000 9.00000 0.33300 0.14300 5.00000 4.00000 3.00000 5.00000 1.00000 5.00000 0.25000 0.16700 1.00000 3.00000 0.11100 0.11100 0.20000 1.00000 0.14300 0.12500 0.12500 0.20000 6.00000 3.00000 4.00000 7.00000 1.00000 2.00000 0.50000 4.00000 5.00000 7.00000 6.00000 8.00000 0.50000 1.00000 0.33300 0.33300 2.00000 0.20000 1.00000 8.00000 2.00000 3.00000 1.00000 1.00000 4.00000 0.25000 0.33300 5.00000 0.25000 3.00000 1.00000 1.00000 octave:2> foo = eig(A) foo = 11.72374 + 0.00000i -1.05925 + 5.81855i -1.05925 - 5.81855i -0.00571 + 2.32593i -0.00571 - 2.32593i -2.03018 + 0.00000i 0.21818 + 0.82953i 0.21818 - 0.82953i on 7/30/04 5:49 PM, Rich Shepard at rshepard at appl-ecosys dot com wrote: > I'm brand-new at using octave. I need to calculate the principal > eigenvector for a symetrical matrix. For the moment, it's 8x8. The installed > version of octave is 2.1.35; I downloaded 2.1.71 yesterday but haven't yet > upgraded. > > I wrote a short shell script: > > #! /usr/bin/octave -pf > # calculate eigenvector for Columbia Gateway scoping. > A = [1.000,0.143,0.333,9.000,0.167,0.200,0.500,0.250; > 7.000,1.000,0.200,9.000,0.333,0.143,5.000,4.000; > 3.000,5.000,1.000,5.000,0.250,0.167,1.000,3.000; > 0.111,0.111,0.200,1.000,0.143,0.125,0.125,0.200; > 6.000,3.000,4.000,7.000,1.000,2.000,0.500,4.000; > 5.000,7.000,6.000,8.000,0.500,1.000,0.333,0.333; > 2.000,0.200,1.000,8.000,2.000,3.000,1.000,1.000; > 4.000,0.250,0.333,5.000,0.250,3.000,1.000,1.000]; > foo = eig(A); > > When I run it this is what I see: > > [rshepard at salmo ~]$ ./gateway.oct > GNU Octave, version 2.1.35 (i386-redhat-linux-gnu). > Copyright (C) 1996, 1997, 1998, 1999, 2000, 2001 John W. Eaton. > This is free software with ABSOLUTELY NO WARRANTY. > For details, type arranty'. > > *** This is a development version of Octave. Development releases > *** are provided for people who want to help test, debug, and improve > *** Octave. > *** > *** If you want a stable, well-tested version of Octave, you should be > *** using one of the stable releases (when this development release > *** was made, the latest stable version was 2.0.16). > > error: ig' undefined near line 5 column 7 > error: evaluating index expression near line 5, column 7 > error: evaluating assignment expression near line 5, column 5 > > What have I missed? > > Thanks, > > Rich ------------------------------------------------------------- Octave is freely available under the terms of the GNU GPL. Octave's home on the web: http://www.octave.org How to fund new projects: http://www.octave.org/funding.html Subscription information: http://www.octave.org/archive.html -------------------------------------------------------------