inconsistent condition numbers from cond, det, inv functions

[David Bateman]

Rolf Fabian wrote:
> Thanks Ben. From your results I conclude that MatLab
> is actually doing something very similar than I did for my
> condh-function. I personally have good reasons not to
> send any code any more to any Octave list. 
Ralf,

I believe you are referring to the message

http://www.nabble.com/polyvalm-problems-for-defective-matrix-input-to15183200.html#a15269047

I can tell you I've made some major changes to many Octave files without
changing the attribution of the copyright/authorship at all in the files
themselves. Look through the changelogs and compare against the files if
you don't believe, me.. I hope to explain to you why I'm comfortable
with this position, and not surprised that this happened in your case.

However, you are essentially making a claim of plagarism and all such
claims need to be taken serious. I was not involved at all in the Octave
project in 1997 and so I believe I can be fairly neutral analysis of the
situation. The change you are referring to can be seen in the Octave
version control system at

http://velveeta.che.wisc.edu/cgi-bin/cvsweb.cgi/octave/scripts/polynomial/polyvalm.m.diff?r1=1.11;r2=1.12

and essentially comes down to the change

--- octave/scripts/polynomial/polyvalm.m 1997/03/27 16:19:15 1.11
+++ octave/scripts/polynomial/polyvalm.m 1997/09/19 22:07:32 1.12
@@ -61,6 +61,10 @@ function y = polyvalm (c, x)

[v, d] = eig (x);

- y = v * diag (polyval (c, diag (d))) * v';
+ if (is_symmetric (x))
+ y = v * diag (polyval (c, diag (d))) * v';
+ else
+ y = v * (diag (polyval (c, diag (d))) / v);
+ endif

endfunction

with the rest being layout/whitespace changes. Yes the attribution in
the file that you included in your patch is missing, so on face value
you are right.

This might be justified by the size of the patch being small (-1 line
and +5 lines of essential code), however I don't take that position. A
change is a change and appropriate citation is necessary. However what
is appropriate citation for a software project? We could include every
person that ever touched a file in a list of authors of all files in
octave. However, as many people have touch many files with Octave that
is unwieldy. In fact there are many projects where individual files have
no authorship attributions. This does not mean that the citation of the
author is not performed. Its just done differently.

Unfortunately, for reasons I don't quite understand, Octave has many
files with copyright assigned to individual authors and this has lead
people contributing to Octave to also include author lines. As we can't
change that now in any sane way, newly contributed files have typically
had the authorship/copyright assigned to the original author, and people
who modify the file aren't cited in the file themselves....

So where are they cited, and in particular where is your contribution of
the Aug 19, 1997 cited? Looking through the file scripts/Changelog
you'll find the following entry

Thu Aug 28 15:31:20 1997  Rolf Fabian  <fabian at olymp.Umwelt.TU-Cottbus.de>

        * polynomial/polyvalm.m: Don't assume orthogonal eigenvectors for
        nonsymmetric matrices.

        * general/tril.m: Fix usage message.

        * polynomial/polyvalm.m: Fix error messages.
        * polynomial/polyderiv.m: Likewise.
        * polynomial/polyval.m: Likewise.

which is the citation of your authorship of the modifications, what was
changed and the date the change was applied to Octave itself. Also
you'll find in

http://www.gnu.org/software/octave/doc/interpreter/Acknowledgements.html#Acknowledgements

your name listed as a contributor to Octave itself, as are all people
who have contributed a modification to Octave. This is the way Octave
has handled all contributions that I've seen. So I believe your implied
claim to plagarism is unfounded. The move to mercurial will help here if
authors contribute their patches as mercurial changesets. In that case
the version control log will also contain the name of the person
responsible for the change.

I hope I have addressed your complaint and that you'll reconsider your
position..

Regards
David

-- 
David Bateman                                David.Bateman at motorola.com
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Parc Les Algorithmes, Commune de St Aubin    +33 6 72 01 06 33 (Mob) 
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