Procedure

   void dvcrss_c ( ConstSpiceDouble s1  [6],
                   ConstSpiceDouble s2  [6],
                   SpiceDouble      sout[6] ) 

Abstract

   Compute the cross product of two 3-dimensional vectors 
   and the derivative of this cross product. 

Required_Reading

   None. 

Keywords

   VECTOR 
   DERIVATIVE
   MATH

Brief_I/O

 
   VARIABLE  I/O  DESCRIPTION 
   --------  ---  -------------------------------------------------- 
   s1        I   Left hand state for cross product and derivative. 
   s2        I   Right hand state for cross product and derivative. 
   sout      O   State associated with cross product of positions. 
 

Detailed_Input

 
   s1       This may be any state vector.  Typically, this 
            might represent the apparent state of a planet or the 
            Sun, which defines the orientation of axes of 
            some coordinate system. 
 
   s2       A state vector. 
 

Detailed_Output

 
   sout     This variable represents the state associated with the 
            cross product of the position components of 's1' and 's2.' 
            In otherwords if s1 = (P1,V1) and s2 = (P2,V2) then 
            'sout' is ( P1xP2, d/dt{ P1xP2 } ) 
 
            'sout' may overwrite 's1' or 's2'. 
 

Parameters

 
   None. 
 

Exceptions

 
   Error free. 
 
   1) If 's1' and 's2'  are large in magnitude (taken together, 
      their magnitude surpasses the limit allow by the 
      computer) then it may be possible to generate a 
      floating point overflow from an intermediate 
      computation even though the actual cross product and 
      derivative may be well within the range of double 
      precision numbers. 
 
      dvcrss_c does NOT check the magnitude of 's1' or 's2'  to 
      insure that overflow will not occur. 
 

Files

 
   None. 
 

Particulars

 
   dvcrss_c calculates the three-dimensional cross product of two 
   vectors and the derivative of that cross product according to 
   the definition.  The components of this state are stored 
   in a local buffer vector until the calculation is complete. 
   Thus sout may overwrite 's1' or 's2'  without interfering with 
   intermediate computations. 
 

Examples

 
          s1                    s2                   sout 
   ----------------------------------------------------------------- 
   (0, 1, 0, 1, 0, 0)  ( 1,  0,  0, 1, 0, 0)  (0, 0, -1, 0,  0, -1 ) 
   (5, 5, 5, 1, 0, 0)  (-1, -1, -1, 2, 0, 0)  (0, 0,  0, 0, 11,-11 ) 
 

Restrictions

 
   None. 
     

Literature_References

 
   None.

Author_and_Institution

 
   W.L. Taber      (JPL) 
   E.D. Wright     (JPL)
 

Version

 
   -CSPICE Version 1.0.0, 23-NOV-2009 (EDW)

Index_Entries

 
   Compute the derivative of a cross product 
 

Link to routine dvcrss_c source file dvcrss_c.c