Procedure

   SpiceDouble vnorm_c ( ConstSpiceDouble v1[3] )

Abstract

   Compute the magnitude of a double precision, 3-dimensional vector.

Required_Reading

   None.

Keywords

 
   VECTOR 
 

Brief_I/O

   VARIABLE  I/O  DESCRIPTION
   --------  ---  --------------------------------------------------
   v1         I   Vector whose magnitude is to be found.

   The function returns the norm of v1.
 

Detailed_Input

   v1             may be any 3-dimensional, double precision vector.
 

Detailed_Output

   The function returns the magnitude of v1 calculated in a numerically 
   stable way.

Parameters

   None.

Exceptions

   Error free.

Files

   None.

Particulars

   vnorm_c takes care to avoid overflow while computing the norm of the
   input vector v1.  vnorm_c finds the component of v1 whose magnitude 
   is the largest.  Calling this magnitude v1max, the norm is computed 
   using the formula
 
       vnorm_c  =  v1max *  ||  (1/v1max) * v1  ||
       
   where the notation ||x|| indicates the norm of the vector x.

Examples

   The following table show the correlation between various input
   vectors v1 and vnorm_c:

   v1                                    vnorm_c
   -----------------------------------------------------------------
   ( 1.e0,    2.e0,   2.e0    )          3.e0
   ( 5.e0,    12.e0,  0.e0    )          13.e0
   ( -5.e-17, 0.0e0,  12.e-17 )          13.e-17
       

Restrictions

   None.
   

Literature_References

   None.

Author_and_Institution

   N.J. Bachman       (JPL)
   W.L. Taber         (JPL)
   W.M. Owen          (JPL)

Version

   -CSPICE Version 1.0.2, 16-JAN-2008   (EDW)

      Corrected typos in header titles:
      
      Detailed Input to Detailed_Input
      Detailed Output to Detailed_Output

   -CSPICE Version 1.0.1, 12-NOV-2006 (EDW)

      Added Parameters section header.

   -CSPICE Version 1.0.0, 16-APR-1999 (NJB)

Index_Entries

   norm of 3-dimensional vector
   

Link to routine vnorm_c source file vnorm_c.c