[Octave-bug-tracker] [bug #40970] inpolygon incompatibility (Octave and Matlab disagrees about points on edges)

[anonymous]

URL:
  <http://savannah.gnu.org/bugs/?40970>

                 Summary: inpolygon incompatibility (Octave and Matlab
disagrees about points on edges)
                 Project: GNU Octave
            Submitted by: None
            Submitted on: Thu 19 Dec 2013 11:37:57 AM UTC
                Category: Libraries
                Severity: 3 - Normal
                Priority: 5 - Normal
              Item Group: Matlab Compatibility
                  Status: None
             Assigned to: None
         Originator Name: Anders A. Søndergaard
        Originator Email: address@hidden
             Open/Closed: Open
         Discussion Lock: Any
                 Release: 3.6.4
        Operating System: GNU/Linux

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Details:

The inpolygon function in Matlab returns 1 if a point is inside
a polygon __or on the edge of it__.

In Octave, inpolygon only returns 1 if the point is strictly inside the
polygon, and 0 if it is on the edge.

The following function demonstrates the incompatibility


function octavematlab()

   xs = [0,1,2]; % Triangle from 0,0 to 1,1 and 2,0
   ys = [0,1,0];

   inmatlab = inpolygon(1,1,xs,ys); % Is the vertex 1,1 in the polygon?

   if inmatlab
     disp('Hello from Matlab!');
   else
     disp('Hello from Octave!');
   end

   xs = [0,1,1,0]; % Rectangle from 0,0 to 1,1
   ys = [1,1,0,0];

   if (inpolygon(0.5,1,xs,ys))  % Is a point on an edge in the polygon?
        disp('Edge is inside polygon');
   else
        disp('Edge is outside polygon');

end


When called from matlab, the result is

Hello from Matlab!
Edge is inside polygon

When called from Octave:

Hello from Octave!
Edge is outside polygon


Anders Søndergaard




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