[Octave-bug-tracker] [bug #53231] Range type should implement division operator for scalars

[Rik]

URL:
  <http://savannah.gnu.org/bugs/?53231>

                 Summary: Range type should implement division operator for
scalars
                 Project: GNU Octave
            Submitted by: rik5
            Submitted on: Mon 26 Feb 2018 05:43:27 PM PST
                Category: Interpreter
                Severity: 3 - Normal
                Priority: 5 - Normal
              Item Group: Feature Request
                  Status: None
             Assigned to: None
         Originator Name: 
        Originator Email: 
             Open/Closed: Open
         Discussion Lock: Any
                 Release: dev
        Operating System: Any

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Details:

While fixing a bug in hist.m I accidentally discovered that division by a
scalar is not implement for Range values.

For example:


octave:2> x = 1:10
x =

    1    2    3    4    5    6    7    8    9   10

octave:3> typeinfo (x)
ans = range
octave:4> y = 3 * x
y =

    3    6    9   12   15   18   21   24   27   30

octave:5> typeinfo (y)
ans = range
octave:6> z = x / 1
z =

    1    2    3    4    5    6    7    8    9   10

octave:7> typeinfo (z)
ans = matrix


This is rather surprising and likely to trip up users.

I was able to work around the limitation by using multiplication, but the code
looks awkward.


new_range = old_range * (1/scalar)


The issue is confirmed by looking at liboctave/array/Range.h where the list of
operators implemented does not include division.


  friend OCTAVE_API Range operator - (const Range& r);
  friend OCTAVE_API Range operator + (double x, const Range& r);
  friend OCTAVE_API Range operator + (const Range& r, double x);
  friend OCTAVE_API Range operator - (double x, const Range& r);
  friend OCTAVE_API Range operator - (const Range& r, double x);
  friend OCTAVE_API Range operator * (double x, const Range& r);
  friend OCTAVE_API Range operator * (const Range& r, double x);


This seems like a simple enough fix to introduce function prototypes for
division by a scalar in Range.h and copy/modify the existing multiplication
code in Range.cc to work for division.





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