[Octave-bug-tracker] [bug #51283] function min/max inconsistent handling of -0

[Joel Dahne]

URL:
  <http://savannah.gnu.org/bugs/?51283>

                 Summary: function min/max inconsistent handling of -0
                 Project: GNU Octave
            Submitted by: urathai
            Submitted on: Wed 21 Jun 2017 08:56:37 AM UTC
                Category: Octave Function
                Severity: 3 - Normal
                Priority: 5 - Normal
              Item Group: Incorrect Result
                  Status: None
             Assigned to: None
         Originator Name: Joel
        Originator Email: 
             Open/Closed: Open
         Discussion Lock: Any
                 Release: 4.2.1
        Operating System: GNU/Linux

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Details:

The min/max functions does not seem to be aware of the difference between -0
and 0. We have (-0 == 0) = 1 and (-0 < 0) = 0, so it is not clear how to
handle this case. The main problem however lies in that the result is
different when comparing scalars versus when comparing vectors. For max we
have

> max (-0, 0) 
ans = 0
>max (0, -0) 
ans = -0
>max ([-0, -0], [0, 0]) 
ans = [-0, -0]
>max ([0, 0], [-0, -0]) 
ans = [0, 0]

It looks like the function make no difference between -0 and 0, it probably
just returns the first (or last?) of them it encounters. But as can be seen
the order differs between scalars and vectors.

I think it would be more natural to return 0 in all cases, but at least be
consistent with it.




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