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Required Reading


   CSPICE_NPLNPT calculates the location on a defined line
   nearest to a specified point, then determines the distance
   between the two points.

   For important details concerning this module's function, please refer to
   the CSPICE routine nplnpt_c.



      linpt    a double precision 3-vector.

      lindir   a double precision 3-vector.

               are, respectively, a point and a direction vector that define
               a line. The line is the set of vectors

                     linept   +   t * linedr

               where t is any real number.

      point    a double precision 3-vector defining a position
               in space.

   the call:

      cspice_nplnpt, linpt, lindir, point, pnear, dist


      pnear   a double precision 3-vector identifying the nearest
              point on the input line to the input 'point'.

      dist    the scalar double precision distance between the
              input line and input point.


   Any numerical results shown for this example may differ between
   platforms as the results depend on the SPICE kernels used as input
   and the machine specific arithmetic implementation.

      ;; Define a point on a line, a direction for the line, and
      ;; an arbitrary point in space.
      linept = [  1.d, 2.d,  3.d ]
      linedr = [  0.d, 1.d,  1.d ]
      point  = [ -6.d, 9.d, 10.d ]

      ;; Calculate the location on the line nearest the point
      ;; and the distance between the location and the defined
      ;; point.
      cspice_nplnpt, linept, linedr, point, pnear, dist
      print, pnear
      print, dist

   IDL outputs for pnear:

      1.0000000   9.0000000   10.000000

   IDL outputs for dist:



   For every line L and point P, there is a unique closest point
   on L to P.  Call this closest point C.  It is always true that
   P - C  is perpendicular to L, and the length of P - C is called
   the "distance" between P and L.

Required Reading



   -Icy Version 1.0.1, 13-JUN-2011, EDW (JPL)

      Edits to I/O and Particulars sections so as to parallel Mice version.

   -Icy Version 1.0.0, 16-JUN-2003, EDW (JPL)


   distance between point and line
   nearest point on line to point

Wed Apr  5 17:58:02 2017