[Octave-bug-tracker] [bug #51785] Inconsistent behavior of various shaped empty index vectors in for loops

[Geoffrey Adams]

URL:
  <http://savannah.gnu.org/bugs/?51785>

                 Summary: Inconsistent behavior of various shaped empty index
vectors in for loops
                 Project: GNU Octave
            Submitted by: biogeo
            Submitted on: Fri 18 Aug 2017 05:52:06 PM UTC
                Category: Interpreter
                Severity: 3 - Normal
                Priority: 5 - Normal
              Item Group: Incorrect Result
                  Status: None
             Assigned to: None
         Originator Name: Geoffrey Adams
        Originator Email: 
             Open/Closed: Open
         Discussion Lock: Any
                 Release: 4.0.3
        Operating System: GNU/Linux

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Details:

When supplying an empty matrix as the index vector to a for loop, the expected
behavior is that the loop body is skipped, as in the following:


for i=[]
    disp('This will never execute');
end


However, for empty matrices that are not shaped as 0-by-0, this is not always
the case. In particular, while the following behaves as expected:


for i=reshape([],1,0)
    disp('This will never execute');
end


the following does not:


for i=reshape([],0,1)
    disp('This line executes, and i is a 0-by-1 matrix');
    disp(i);
end





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