Procedure

   pl2nvp_c ( Plane to normal vector and point ) 

   void pl2nvp_c ( ConstSpicePlane   * plane,
                   SpiceDouble         normal[3],
                   SpiceDouble         point [3]  )

Abstract

   Return a unit normal vector and point that define a specified
   plane.

Required_Reading

   PLANES

Keywords

   GEOMETRY
   MATH
   PLANE

Brief_I/O

   VARIABLE  I/O  DESCRIPTION
   --------  ---  --------------------------------------------------
   plane      I   A SPICE plane.
   normal,
   point      O   A unit normal vector and point that define `plane'.

Detailed_Input

   plane       is a SPICE plane.

Detailed_Output

   normal,
   point       are, respectively, a unit normal vector and point
               that define the geometric plane represented by
               `plane'. Let the symbol < a, b > indicate the inner
               product of vectors `a' and `b'; then the geometric
               plane is the set of vectors `x' in three-dimensional
               space that satisfy

                  < x - point, normal >  =  0.

               `point' is always the closest point in the input
               plane to the origin. `point' is always a
               non-negative scalar multiple of `normal'.

Parameters

   None.

Exceptions

   Error free.

   1)  The input plane MUST have been created by one of the CSPICE
       routines

          nvc2pl_c ( Normal vector and constant to plane )
          nvp2pl_c ( Normal vector and point to plane    )
          psv2pl_c ( Point and spanning vectors to plane )

       Otherwise, the results of this routine are unpredictable.

Files

   None.

Particulars

   CSPICE geometry routines that deal with planes use the `plane'
   data type to represent input and output planes. This data type
   makes the routine interfaces simpler and more uniform.

   The CSPICE routines that produce SPICE planes from data that
   define a plane are:

      nvc2pl_c ( Normal vector and constant to plane )
      nvp2pl_c ( Normal vector and point to plane    )
      psv2pl_c ( Point and spanning vectors to plane )

   The CSPICE routines that convert SPICE planes to data that
   define a plane are:

      pl2nvc_c ( Plane to normal vector and constant )
      pl2nvp_c ( Plane to normal vector and point    )
      pl2psv_c ( Plane to point and spanning vectors )

Examples

   1)  Given a plane normal and constant, find a point in
       the plane. `point' is the point we seek.

          nvc2pl_c (  normal, const, &plane  );
          pl2nvp_c ( &plane, normal,  point  );

Restrictions

   None.

Literature_References

   [1]  G. Thomas and R. Finney, "Calculus and Analytic Geometry,"
        7th Edition, Addison Wesley, 1988.

Author_and_Institution

   N.J. Bachman        (JPL)
   J. Diaz del Rio     (ODC Space)

Version

   -CSPICE Version 1.0.1, 24-AUG-2021 (JDR)

       Edited the header to comply with NAIF standard.

   -CSPICE Version 1.0.0, 05-MAR-1999 (NJB)

Index_Entries

   plane to normal vector and point

Link to routine pl2nvp_c source file pl2nvp_c.c