From help-octave-request  Thu May 27 13:53:43 1993
Subject: sum(null matrix) becomes null matrix not zero
From: che6yoh at sun dot leeds dot ac dot uk
To: twang at meishan dot animal dot uiuc dot edu
Cc: help-octave
Date: Thu, 27 May 93 19:50:00 BST

Hello.
Thank you very much.
  >Date: Thu, 27 May 1993 13:37:49 -0500
  >From: Tianlin Wang <twang at edu dot uiuc dot animal dot meishan>
  >
  >	  If I execute 
  >	  >>a=[]
  >	  >>b=sum(a)
  >	  The result becomes b=[].
  >	  Is this specification of octave?
  >	  I expected b became zero like MATLAB.
  >
  >I like b=[], because b=0 can fool people
  > 
  >	  1. The results of expm are strange.
  >		    Does the problem occure only on my system?
  >I think, octave uses eigenvectors to calculate expm, it could fail for 
  >some ill matrice. However, MATLAB built-in expm function uses more general
  >and reliable algorithm.
  >
  >An octive user, University of Illinois
  >
I am very glad to know that the cause of the problems was not
my installation.

I hope many users improve octave, though I can't check the
source codes.
It is a merit of freeware softwares, I think.

Yoshihiro Hashimoto
Dept. of Systems Eng., Nagoya Inst. of Tech.
hasimoto at coral dot system dot nitech dot ac dot jp
[Now]Dept. of Chem. Eng., The Univ. of Leeds
che6yoh at sun dot leeds dot ac dot uk
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