[Octave-bug-tracker] [bug #52706] mpower compatibility behavior

[Marco Caliari]

URL:
  <http://savannah.gnu.org/bugs/?52706>

                 Summary: mpower compatibility behavior
                 Project: GNU Octave
            Submitted by: caliari
            Submitted on: Wed 20 Dec 2017 11:53:09 AM UTC
                Category: Octave Function
                Severity: 2 - Minor
                Priority: 5 - Normal
              Item Group: Matlab Compatibility
                  Status: None
             Assigned to: None
         Originator Name: 
        Originator Email: 
             Open/Closed: Open
         Discussion Lock: Any
                 Release: dev
        Operating System: GNU/Linux

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Details:

It is easy to check that, e.g., A^7 is computed in octave as


A2 = A * A;
A4 = A2 * A2;
(A * A2) * A4


while in matlab as


A2 = A * A;
A4 = A2 * A2;
A4 * (A2 * A)


In exact arithmetic it is obviously the same. The modification would be


result = result * atmp; -> result = atmp * result;


in xpow.cc. Any objections?




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