DISTANCELINES3D Minimal distance between two 3D lines.

   D = distanceLines3d(LINE1, LINE2);
   Returns the distance between line LINE1 and the line LINE2, given as:
   LINE1 : [x0 y0 z0 dx dy dz] (or M-by-6 array)
   LINE2 : [x0 y0 z0 dx dy dz] (or N-by-6 array)
   D     : (positive) array M-by-N

   [D, PT1, PT2] = distanceLines3d(LINE1, LINE2);
   Also returns the points located on LINE1 and LINE2 corresponding to the
   shortest distance. 
   One should get the following:
   distancePoints3d(PT1, PT2) - D == 0


   Example
     line1 = [2 3 4 0 1 0];
     line2 = [8 8 8 0 0 1];
     distanceLines3d(line1, line2)
     ans = 
         6.0000

   See also:
   lines3d, distancePoints3d

   ---------
   authors: Brandon Baker, oqilipo, David Legland
   created January 19, 2011

Package: matgeom