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Abstract
I/O
Examples
Particulars
Required Reading
Version
Index_Entries

Abstract


   CSPICE_PLTNRM computes an outward normal vector of a triangular plate.
   The vector does not necessarily have unit length.

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

I/O


   Given:

      v1,
      v2,
      v3         are 3-vectors constituting the vertices of
                 a triangular plate.

   the call:

      cspice_pltnrm, v1, v2, v3, normal

   returns:

      normal     is an outward normal vector of the plate defined by
                 the input vertices. The order of the vertices is
                 used to determine the choice of normal direction:
                 the normal vector is

                    ( V2 - V1 ) x ( V3 - V2 )

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.

   Compute an outward normal of an equilateral triangle lying
   in the X-Y plane and centered at the origin.

      PRO PLTNRM_T

         s = sqrt(3.D)/2.D;

         v1 = [  s,  -0.5D,  0.D]
         v2 = [ 0.D,  1.D,   0.D]
         v3 = [ -s,  -0.5D,  0.D]

         cspice_pltnrm, v1, v2, v3, normal

         print, 'NORMAL = ', normal

      END

   IDL outputs:

      NORMAL =        0.0000000       0.0000000       2.5980762

Particulars


   This routine saves computation time by not scaling the output
   vector to unit length. The caller can scale the vector using
   the routine cspice_vhat.

Required Reading


   ICY.REQ
   DSK.REQ

Version


   -Icy Version 1.0.0, 15-DEC-2016, ML (JPL), EDW (JPL)

Index_Entries


   compute normal vector of triangular plate from vertices



Wed Apr  5 17:58:02 2017