Polygon:

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   Generate the properties for a polygon given vertices in the form v(3,n).
   It assumes that the polygon is planar. It computes an average normal
   at all vertices.
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   Form:
   [area, n, r] = Polygon( v )
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   ------
   Inputs
   ------
   v          (3,:)       Vertices

   -------
   Outputs
   -------
   area       (1,1)       Area of the polygon
   n          (3,1)       Normal
   r          (3,1)       Geometric center

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Children:

Common: Math/Cross
Common: Math/DupVect