Abstract

   CSPICE_CLIGHT returns the double precision value for the constant
   speed of light in a vacuum (IAU official value, in km/sec).

I/O

   The call:

      clight = cspice_clight( )

   returns:

      clight   the IAU official value for the speed of light in vacuum:
               299792.458 km/sec.

               help, clight
                  DOUBLE = Scalar

Parameters

   None.

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.

   1) Display the IAU official double precision value
      for the constant speed of light in the vacuum, in km/sec.

      Example code begins here.


      PRO clight_ex1

         print, FORMAT='("Speed of light: ", F12.4)', cspice_clight()

      END


      When this program was executed on a Mac/Intel/IDL8.x/64-bit
      platform, the output was:


      Speed of light:  299792.4580

Particulars

   The function always returns the constant value shown above.

Exceptions

   Error free.

Files

   None.

Restrictions

   None.

Required_Reading

   ICY.REQ

Literature_References

   None.

Author_and_Institution

   J. Diaz del Rio     (ODC Space)
   E.D. Wright         (JPL)

Version

   -Icy Version 1.0.1, 25-AUG-2021 (JDR)

       Edited the header to comply with NAIF standard. Added example's
       problem statement and reformatted example's output.

       Added -Parameters, -Particulars, -Exceptions, -Files, -Restrictions,
       -Literature_References and -Author_and_Institution sections.

       Removed reference to the routine's corresponding CSPICE header from
       -Abstract section.

       Added argument's type and size information in the -I/O section.

   -Icy Version 1.0.0, 16-JUN-2003 (EDW)

Index_Entries

   measured velocity of light in a vacuum