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Abstract
I/O
Examples
Particulars
Required Reading
Version
Index_Entries

Abstract


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

I/O


   Given:

      linpt    [3,1] = size(linpt); double = class(linpt)

      lindir   [3,1] = size(lindir); double = class(lindir)

               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 point in 3-dimensional space.

               [3,n] = size(point); double = class(point)

   the call:

      [ pnear, dist ] = cspice_nplnpt( linpt, lindir, point )

   returns:

      pnear   the nearest point on the input line to the input 'point'.

              [3,1] = size(pnear); double = class(pnear)

      dist    distance between the input line and input point.

              [1,n] = size(dist); double = class(dist)

Examples


   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, 2,  3 ]';
      linedr = [  0, 1,  1 ]';
      point  = [ -6, 9, 10 ]';

      %
      % Calculate the location on the line nearest the point
      % and the distance between the location and the defined
      % point.
      %
      [ pnear, dist ] = cspice_nplnpt( linept, linedr, point )

   MATLAB outputs:

      pnear =

           1
           9
          10


      dist =

           7

Particulars


   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


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

   MICE.REQ

Version


   -Mice Version 1.0.0, 14-NOV-2013, EDW (JPL), SCK (JPL)

Index_Entries


   distance between point and line
   nearest point on line to point


Wed Apr  5 18:00:33 2017