Return the position of a 3D point projected on a 3D line.

   T = linePosition3d(POINT, LINE)
   Computes position of point POINT on the line LINE, relative to origin
   point and direction vector of the line.
   LINE has the form [x0 y0 z0 dx dy dy],
   POINT has the form [x y z], and is assumed to belong to line.
   The result T is the value such that POINT = LINE(1:3) + T * LINE(4:6).
   If POINT does not belong to LINE, the position of its orthogonal
   projection is computed instead. 

   T = linePosition3d(POINT, LINES)
   If LINES is an array of NL lines, return NL positions, corresponding to
   each line.

   T = linePosition3d(POINTS, LINE)
   If POINTS is an array of NP points, return NP positions, corresponding
   to each point.

   See also:
   lines3d, createLine3d, distancePointLine3d, projPointOnLine3d

   ---------
   author : David Legland 
   INRA - TPV URPOI - BIA IMASTE
   created the 17/02/2005.

Package: matgeom