BISECTOR Return the bisector of two lines, or 3 points.

   RAY = bisector(LINE1, LINE2);
   create the bisector of the two lines, given as [x0 y0 dx dy].

   RAY = bisector(P1, P2, P3);
   create the bisector of lines (P2 P1) and (P2 P3).

   The result has the form [x0 y0 dx dy], with [x0 y0] being the origin
   point ans [dx dy] being the direction vector, normalized to have unit
   norm.
   
   See also:
   lines2d, rays2d

   ---------
 Author: David Legland
 e-mail: david.legland@grignon.inra.fr
 created the 31/10/2003.
 Copyright 2010 INRA - Cepia Software Platform.

Package: matgeom