From help-octave-request at bevo dot che dot wisc dot edu  Wed Jan 27 18:30:40 1999
Subject: Colon inconsistency between Matlab and Octave
From: Arno Peters <A dot W dot Peters at ieee dot org>
To: help-octave at bevo dot che dot wisc dot edu
Date: Thu, 28 Jan 1999 01:28:51 +0100 (CET)


SUMMARY:

1) In Matlab, the colon operator _always_ returns a column vector.

2) pause flushes buffers in Matlab, not in Octave

Verified with Octave version 2.1.10 and 2.0.13.


Case 1:

octave> a = [1 2; 3 4];
octave> a(:)
ans =

  1
  3
  2
  4

Case 2:

octave> b = [1; 2; 3; 4];
octave> b(:)
ans =

  1
  2
  3
  4

Case 3:

octave> c = [1 2 3 4];
octave> c(:)
ans =

  1  2  3  4


Cases 1 and 2 are consistent with Matlab but for case 3 the results
should be identical to case 2.  I guess I would expect this also from
looking at the behaviour of the colon operator on matrixes.

Currently I am unable to verify with Matlab but I have seen at least
one script that relies on this feature: robot, a set of scripts in the
contributed directory of the Matlab site.  The Robot Toolbox homepage
is at

        http://www.cat.csiro.au/dmt/programs/autom/pic/matlab.html

Contrary what the author claims in the documentation, the demo runs
perfectly except for this minor incompatibility.  BTW, he used Matlab
version 4 and Octave version 1.1.1.  Things have changed considerably
since then (1996).

At least options 2 and 3 of 'rtdemo' will bomb out after you hit one
or more keys.  This way, I also found out that apparently 'pause' will
flush the buffers in Matlab.  When you run the other demos will also
make this clear because in Octave you don't see a thing until you hit
a key or several keys.

Thanks for any feedback you can provide.

-- 
Arno Peters