[Octave-bug-tracker] [bug #50776] Octave logical indexing inconsistent with Matlab

[Richard]

URL:
  <http://savannah.gnu.org/bugs/?50776>

                 Summary: Octave logical indexing inconsistent with Matlab
                 Project: GNU Octave
            Submitted by: crobar
            Submitted on: Mon 10 Apr 2017 10:12:45 AM UTC
                Category: Interpreter
                Severity: 3 - Normal
                Priority: 5 - Normal
              Item Group: Matlab Compatibility
                  Status: None
             Assigned to: None
         Originator Name: Richard Crozier
        Originator Email: 
             Open/Closed: Open
         Discussion Lock: Any
                 Release: dev
        Operating System: GNU/Linux

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Details:

Octave does not use the same rules for doing logical indexing on vectors as
Matlab in terms of the shape of the output. In Matlab the rule seems to be:
for vectors, return always the same shape of vector being indexed, for
anything else return a column vector

For example, in Matlab:


>> a = reshape (1:3, 1,1,3)

a(:,:,1) =

     1.0000e+000


a(:,:,2) =

     2.0000e+000


a(:,:,3) =

     3.0000e+000

>> b = true(1,3)

b =

  1×3 logical array

   1   1   1

>> a(b)

ans(:,:,1) =

     1.0000e+000


ans(:,:,2) =

     2.0000e+000


ans(:,:,3) =

     3.0000e+000

>> size (a(b))

ans =

     1.0000e+000     1.0000e+000     3.0000e+000


In Octave:


octave:15> a = reshape (1:3, 1,1,3)
a =

ans(:,:,1) =  1
ans(:,:,2) =  2
ans(:,:,3) =  3

octave:16> b = true(1,3)
b =

   1   1   1

octave:17> a(b)
ans =

   1   2   3

octave:18> size(a(b))
ans =

   1   3



This is using a dev version of Octave, but from quite a while ago, but I've
even deleted the repo clone I built it from, so I can't give hg id:


octave:19> ver
----------------------------------------------------------------------
GNU Octave Version: 4.1.0+
GNU Octave License: GNU General Public License
Operating System: Linux 4.4.0-34-generic #53~14.04.1-Ubuntu SMP Wed Jul 27
16:56:40 UTC 2016 x86_64
----------------------------------------------------------------------
Package Name  | Version | Installation directory
--------------+---------+-----------------------
     control  |   2.8.1 | /home/rcrozier/octave/control-2.8.1
      odepkg *|   0.8.5 | /home/rcrozier/octave/odepkg-0.8.5
      signal  |   1.3.2 | /home/rcrozier/octave/signal-1.3.2








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