EDGEANGLE Return angle of edge.

   A = edgeAngle(EDGE)
   Returns the angle between horizontal, right-axis and the edge EDGE.
   Angle is given in radians, between 0 and 2*pi, in counter-clockwise
   direction. 
   Notation for edge is [x1 y1 x2 y2] (coordinates of starting and ending
   points).

   Example
   p1 = [10 20];
   p2 = [30 40];
   rad2deg(edgeAngle([p1 p2]))
   ans = 
       45

   See also
   edges2d, angles2d, edgeAngle, lineAngle, edgeLength

   ---------
   author : David Legland 
   INRA - TPV URPOI - BIA IMASTE
   created the 06/04/2003.

Package: matgeom