From help-octave-request at bevo dot che dot wisc dot edu  Thu Mar  4 03:36:01 1999
Subject: sqrtm
From: "John W. Eaton" <jwe at bevo dot che dot wisc dot edu>
To: Van den Eynde Gert <gvdeynde at sckcen dot be>
Cc: "'help-octave at bevo dot che dot wisc dot edu'" <help-octave@bevo.che.wisc.edu>
Date: Thu, 4 Mar 1999 03:34:36 -0600 (CST)

On  4-Mar-1999, Van den Eynde Gert <gvdeynde at sckcen dot be> wrote:

| I recently bumped into a very recent article by
| Nick Higham about computing the matrix square root
| in a better way than is used now in Matlab and Octave.
| 
| He includes an m-file in the article, but it seems 
| it's going to be part of the next Matlab release.
| 
| Is it (legally) possible to include this also in
| Octave ? Maybe not the mfile itself, but if it gets
| coded into liboctave I see no problem....

One way around the problem would be to ask the original author to
release a version of his code under the GPL too.  That might work
unless he has already signed an exclusive copyright assignment to the
MathWorks.  In that case, we might be out of luck unless someone can
implement the algorithm independently.

But that looks like a sticky situation to me.  The paper includes the
old and the new sqrtm, both with MathWorks copyright notices.  The
algorithm is described in the paper, but could anyone actually
implement it without generating essentially the same code?  Would they
sue for copyright infringement?  Who knows?

Just for the record, they did send a letter to at least one Octave
contributor asking him to stop distributing some M-files because they
claimed copyright infringement.

jwe