Procedure

   void psv2pl_c ( ConstSpiceDouble    point[3],
                   ConstSpiceDouble    span1[3],
                   ConstSpiceDouble    span2[3],
                   SpicePlane        * plane    ) 

Abstract

 
   Make a CSPICE plane from a point and two spanning vectors. 
 

Required_Reading

 
   PLANES 
 

Keywords

 
   GEOMETRY 
   MATH 
   PLANE 
 

Brief_I/O

 
   Variable  I/O  Description 
   --------  ---  -------------------------------------------------- 
   point, 
   span1, 
   span2      I   A point and two spanning vectors defining a plane. 
   plane      O   A CSPICE plane representing the plane. 
 

Detailed_Input

 
   point, 
   span1, 
   span2          are, respectively, a point and two spanning vectors 
                  that define a geometric plane in three-dimensional 
                  space. The plane is the set of vectors 
 
                     point   +   s * span1   +   t * span2 
 
                  where s and t are real numbers.  The spanning 
                  vectors span1 and span2 must be linearly 
                  independent, but they need not be orthogonal or 
                  unitized. 
 

Detailed_Output

 
   plane          is a CSPICE plane that represents the geometric 
                  plane defined by point, span1, and span2. 
 

Parameters

 
   None. 
 

Exceptions

 
   1)  If span1 and span2 are linearly dependent, then the vectors 
       point, span1, and span2 do not define a plane.  The error 
       SPICE(DEGENERATECASE) is signaled. 
 

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 subroutine interfaces simpler and more uniform. 
 
   The CSPICE routines that produce CSPICE 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 CSPICE 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 ) 
 
   Any of these last three routines may be used to convert this 
   routine's output, plane, to another representation of a 
   geometric plane. 
 

Examples

 
   1)  Project a vector v orthogonally onto a plane defined by 
       point, span1, and span2.  proj is the projection we want; it 
       is the closest vector in the plane to v. 
 
          psv2pl_c ( point,  span1,   span2,  &plane ); 
          vprjp_c  ( v,      &plane,  proj           );
 
 
   2)  Find the plane determined by a spacecraft's position vector 
       relative to a central body and the spacecraft's velocity 
       vector.  We assume that all vectors are given in the same 
       coordinate system. 
 
          /.
          pos is the spacecraft's position, relative to 
          the central body.  vel is the spacecraft's velocity 
          vector.  pos is a point (vector, if you like) in 
          the orbit plane, and it is also one of the spanning 
          vectors of the plane. 
          ./
          psv2pl_c ( pos, pos, vel, &plane );
           
 

Restrictions

 
   None. 
 

Literature_References

 
   [1] `Calculus and Analytic Geometry', Thomas and Finney. 
 

Author_and_Institution

 
   N.J. Bachman   (JPL) 
 

Version

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

Index_Entries

 
   point and spanning vectors to plane 
 

Link to routine psv2pl_c source file psv2pl_c.c