From help-octave-request at bevo dot che dot wisc dot edu  Tue Feb 10 16:27:15 1998
Subject: Empty matrix question
From: "John W. Eaton" <jwe at bevo dot che dot wisc dot edu>
To: Andy Adler <adlera at njc dot org>
Cc: help-octave at bevo dot che dot wisc dot edu
Date: Tue, 10 Feb 1998 16:27:37 -0600

On 10-Feb-1998, Andy Adler <adlera at njc dot org> wrote:

| ( On a side note, The abstract of one of the articles
|   referenced by the octave docs talks about the inadequacy
|   of the MATLAB empty matrix realization. This must explain
|   why Octave is implemented the way it is
| 
|   Does anyone feel like explaining to me what the deficiencies are?
| 
|   [ Nett, CN.  Haddad, WM.IEEE Trans Automatic Control. 38:771-5. 1993
|    A system-theoretic appropriate realization of the empty matrix concept
|    Abstract: A system-theoretic appropriate realization of the empty
|    matrix concept is effectively utilized to transparently handle
|    static and single vector input, single vector output systems within
|    the more general context of dynamic, two vector input, two vector
|    output systems.  The deficiencies of the present MATLAB realization
|    of this concept are described. ]  )

The idea is that if you allow empty matrices to have one nonzero
dimension, you can come up with rules that are consistent with the
existing ones for matrix algebra.  If you consider every empty matrix
to be the same as Matlab does (all are 0x0), then the rules are not
consistent.

jwe