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Empty matrix question
From: |
Andy Adler |
Subject: |
Empty matrix question |
Date: |
Tue, 10 Feb 1998 12:00:15 -0700 (MST) |
I'm having a problem with empty matrices.
There's probably an octave preference variable to do this
but I couldn't find it. (So far 90% of my questions to
help-octave have been answered by a preference variable)
Anyway, here's the sample code
octave:54> vector=ones(1,5);
octave:55> numfix=0;
octave:56> vector(1:numfix)=zeros(numfix,1);
error: A([]) = X: X must also be an empty matrix
error: evaluating assignment expression near line 56, column 17
"numfix" is not necessarily zero in the "real" code, but can
be zero if there are no elements to "fix"
The problem seems to be that the matrices are different types
of empty matrix
octave:58> vector(1:numfix)
ans = [](0x0)
octave:59> zeros(numfix,1)
ans = [](0x1)
Because this works if I try
octave:60> vector(1:numfix)=zeros(0,0);
I realize that I could fix this code using something like
octave:56> vector(1:numfix)=zeros(numfix, (numfix>=1) );
but this seems to be inelegant.
Is there a way to change it?
( 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. ] )
_____________________________________________________________________
Andy Adler, | Pulmonary Physiology Unit | Lab 303-398-1626
address@hidden | National Jewish Center,Denver,USA | Fax 303-398-1607
Just because you're not paranoid doesn't mean they're not out to get you
- Empty matrix question,
Andy Adler <=