[Octave-bug-tracker] [bug #46892] subsref for OO @class failed to be called within method function.

[Rik]

URL:
  <http://savannah.gnu.org/bugs/?46892>

                 Summary: subsref for OO @class failed to be called within
method function.
                 Project: GNU Octave
            Submitted by: rik5
            Submitted on: Wed 13 Jan 2016 03:55:36 PM PST
                Category: Interpreter
                Severity: 3 - Normal
                Priority: 5 - Normal
              Item Group: Incorrect Result
                  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:

The failing code is taken from examples/code/@polynomial/plot.m.

The code is 


function h = plot (p, varargin)
  n = 128;
  rmax = max (abs (roots (p.poly)));
  x = [0 : (n - 1)] / (n - 1) * 2.2 * rmax - 1.1 * rmax;
  if (nargout > 0)
    h = plot (x, p(x), varargin{:});
  else
    plot (x, p(x), varargin{:});
  endif
endfunction


The code makes use of overloading for the subsref function so that p(x)
calculates the value of the polynomial at the points x.  Unfortunately, the
overloaded subsref is not called and it is treated as normal indexing which
then fails because some of the x values are not integers.


cd examples/code
../../run-octave -f --no-gui
p = polynomial ([1 0 1])
p = 1 + X ^ 2
plot (p)
error: p(-1.1): subscripts must be either integers 1 to (2^31)-1 or logicals
error: called from
    plot at line 10 column 5








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