[Octave-bug-tracker] [bug #62079] delaunayn function returns incorrect vertex order

[anonymous]

URL:
  <https://savannah.gnu.org/bugs/?62079>

                 Summary: delaunayn function returns incorrect vertex order
                 Project: GNU Octave
            Submitted by: None
            Submitted on: Fri 18 Feb 2022 04:10:48 PM UTC
                Category: Octave Function
                Severity: 3 - Normal
                Priority: 5 - Normal
              Item Group: Inaccurate Result
                  Status: None
             Assigned to: None
         Originator Name: Trevor B
        Originator Email: trbx174@protonmail.com
             Open/Closed: Open
                 Release: 6.4.0
         Discussion Lock: Any
        Operating System: GNU/Linux

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Details:

If I define a vector of points as

    P = [-2.6105e-01,3.5877e-01; 2.6105e-01, 3.5877e-01; -1.2939e-09,
-4.4029e-01];

I can use the delaunayn(P) command to obtain the triangulation that forms from
those points. The result I get is [1, 2, 3]. This is wrong because of the
direction of the vertices; for a positive (right hand rule in 2D) triangle,
the node order should be [1,3,2]. The result [1,3,2] is returned by a similar
software ‘Matlab’. The issue with the order of these vertices is that it
can cause ill-defined behavior when porting some scripts to Octave.




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