bugGNU Octave - Bugs: bug #45611, help text for length function...


bug #45611: help text for length function should describe behavior for n-D arrays, not just 2d matrices

Submitter:  Nicholas Jankowski <nrjank>
Submitted:  Fri 24 Jul 2015 02:37:11 AM UTC
Category:  Octave Function Severity:  3 - Normal
Priority:  5 - Normal Item Group:  Documentation
Status:  Fixed Assigned to:  None
Originator Name:  Nick Jankowski Open/Closed:  * Closed
Release:  * 4.0.0 Operating System:  * Microsoft Windows
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Sun 26 Jul 2015 03:18:37 AM UTC, comment #1: 

Changed the documentation for length() to clarify it as you suggested in this changeset (http://hg.savannah.gnu.org/hgweb/octave/rev/fc23fbe05f3a).  This will be part of the 4.0.1 bug fix release.

Rik <rik5>
Project Administrator
Fri 24 Jul 2015 02:37:11 AM UTC, original submission:  

minor detail, but it confused me for a second. Looking at the help text for the length function, it states: 

"...For matrix objects, the length is the number of rows or columns, whichever is greater (this odd definition is used for compatibility with MATLAB)."

in both Octave and ML the behavior of the function is to give max(size(A)).  This carries through for n-dimensional arrays as well, so a dim3 vector (1x1xn) will return 'n'.  I would recommend a help text change to something like the following to be more generic:

... to maintain MATLAB compatibility, the length for matrix and n-dimensional array objects is the number of elements in the longest dimension, such that length(A) is equivalent to max(size(A)).

A = ones(3,7,2);
  ==> ans = 7
@end example


I did see bug #45138 about documenting the different behavior of length. Might be worth the explicit dimension if its usage elsewhere is usually different.

Nicholas Jankowski <nrjank>
Project Member


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    Date Changed by Updated Field Previous Value => Replaced by
    2015-07-26 rik5 StatusNone Fixed
        Open/ClosedOpen Closed

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