From bug-octave-request at bevo dot che dot wisc dot edu  Tue Feb  3 14:52:08 1998
Subject: Array select bug(feature)?
From: "John W. Eaton" <jwe at bevo dot che dot wisc dot edu>
To: U-E59264-Osman Buyukisik <buyuk at c0230 dot ae dot ge dot com>
Cc: bug-octave at bevo dot che dot wisc dot edu
Date: Tue, 3 Feb 1998 14:52:00 -0600

On  3-Feb-1998, U-E59264-Osman Buyukisik <buyuk at c0230 dot ae dot ge dot com> wrote:

| octave-2.0.9.96 with gcc/f2c on hpux-10.20 :
| 
|  
| x=[1,2,3,4,5,6]'
| mask1=[1,0,1,0,1,1]'
| mask2=[1,1,1,1,1,1]'
| x(mask2) gives me different results on octave and matlab. 
| octave :
| 
| octave:53> x(mask2)
| ans =
| 
|   1
|   1
|   1
|   1
|   1
|   1
| 
| On Matlab :
| >> x(mask2)
| 
| ans =
| 
|      1
|      2
|      3
|      4
|      5
|      6
| 
| Which is the expected result. However x(mask1) is the same on both
| systems!
| Bug/feature? I am trying to convert matlab scripts.

Bug (in Matlab) because when the mask is all ones and the same size as
the array that's being indexed, the meaning of the operation is
ambiguous.  Octave allows you to choose the meaning you prefer, by
giving you the prefer_zero_one_indexing variable.  Set it to 1 and
Octave will be compatible with Matlab's behavior.

jwe