## Copyright (C) 2004-2011 David Legland <david.legland@grignon.inra.fr>
## Copyright (C) 2004-2011 INRA - CEPIA Nantes - MIAJ (Jouy-en-Josas)
## Copyright (C) 2012 Adapted to Octave by Juan Pablo Carbajal <carbajal@ifi.uzh.ch>
## All rights reserved.
## 
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## modification, are permitted provided that the following conditions are met:
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## -*- texinfo -*-
## @deftypefn {Function File} {@var{n} =} planeNormal (@var{plane})
# Compute the normal to a plane
#
#   N = planeNormal(PLANE) 
#   compute the normal of the given plane
#   PLANE : [x0 y0 z0 dx1 dy1 dz1 dx2 dy2 dz2]
#   N : [dx dy dz]
#   
## @seealso{planes3d, createPlane}
## @end deftypefn

function n = planeNormal(plane)

  n = cross (plane(:,4:6), plane(:, 7:9), 2);

endfunction