INTERSECTLINES Return all intersection points of N lines in 2D.

   PT = intersectLines(L1, L2);
   returns the intersection point of lines L1 and L2. L1 and L2 are 1-by-4
   row arrays, containing parametric representation of each line (in the
   form [x0 y0 dx dy], see 'createLine' for details).
   
   In case of colinear lines, returns [Inf Inf].
   In case of parallel but not colinear lines, returns [NaN NaN].

   If each input is [N*4] array, the result is a [N*2] array containing
   intersections of each couple of lines.
   If one of the input has N rows and the other 1 row, the result is a
   [N*2] array.

   PT = intersectLines(L1, L2, EPS);
   Specifies the tolerance for detecting parallel lines. Default is 1e-14.

   Example
   line1 = createLine([0 0], [10 10]);
   line2 = createLine([0 10], [10 0]);
   point = intersectLines(line1, line2)
   point = 
       5   5

   See also
   lines2d, edges2d, intersectEdges, intersectLineEdge
   intersectLineCircle

   ---------
   author : David Legland 
   INRA - TPV URPOI - BIA IMASTE
   created the 31/10/2003.

Package: matgeom