/*

-Procedure  rpd_c ( Radians per degree ) 

-Abstract
 
   Return the number of radians per degree.

-Disclaimer

   THIS SOFTWARE AND ANY RELATED MATERIALS WERE CREATED BY THE
   CALIFORNIA INSTITUTE OF TECHNOLOGY (CALTECH) UNDER A U.S.
   GOVERNMENT CONTRACT WITH THE NATIONAL AERONAUTICS AND SPACE
   ADMINISTRATION (NASA). THE SOFTWARE IS TECHNOLOGY AND SOFTWARE
   PUBLICLY AVAILABLE UNDER U.S. EXPORT LAWS AND IS PROVIDED "AS-IS"
   TO THE RECIPIENT WITHOUT WARRANTY OF ANY KIND, INCLUDING ANY
   WARRANTIES OF PERFORMANCE OR MERCHANTABILITY OR FITNESS FOR A
   PARTICULAR USE OR PURPOSE (AS SET FORTH IN UNITED STATES UCC
   SECTIONS 2312-2313) OR FOR ANY PURPOSE WHATSOEVER, FOR THE
   SOFTWARE AND RELATED MATERIALS, HOWEVER USED.

   IN NO EVENT SHALL CALTECH, ITS JET PROPULSION LABORATORY, OR NASA
   BE LIABLE FOR ANY DAMAGES AND/OR COSTS, INCLUDING, BUT NOT
   LIMITED TO, INCIDENTAL OR CONSEQUENTIAL DAMAGES OF ANY KIND,
   INCLUDING ECONOMIC DAMAGE OR INJURY TO PROPERTY AND LOST PROFITS,
   REGARDLESS OF WHETHER CALTECH, JPL, OR NASA BE ADVISED, HAVE
   REASON TO KNOW, OR, IN FACT, SHALL KNOW OF THE POSSIBILITY.

   RECIPIENT BEARS ALL RISK RELATING TO QUALITY AND PERFORMANCE OF
   THE SOFTWARE AND ANY RELATED MATERIALS, AND AGREES TO INDEMNIFY
   CALTECH AND NASA FOR ALL THIRD-PARTY CLAIMS RESULTING FROM THE
   ACTIONS OF RECIPIENT IN THE USE OF THE SOFTWARE.

-Required_Reading

   None.

-Keywords 
 
   CONSTANTS 

*/

   #include <math.h>
   #include "SpiceUsr.h"

   SpiceDouble rpd_c ( void )

/*

-Brief_I/O
 
   The function returns the number of radians per degree. 
 
-Detailed_Input 
 
   None. 
 
-Detailed_Output 

   The function returns the number of radians per degree: pi/180.
   The value of pi is determined by the ACOS function. That is,

      rpd = acos ( -1. ) / 180.

-Files 
 
   None. 
 
-Exceptions 
 
   Error free. 
 
-Particulars 
 
   When the function is referenced, the value computed as shown 
   above is returned.
 
-Parameters 
 
   None. 

-Examples
 
   The code fragment below illustrates the use of rpd_c.
 
      /. Convert all angles to radians for output  ./

         clock *= rpd_c() 
         cone  *= rpd_c() 
         twist *= rpd_c()  

-Restrictions

   None.

-Literature_References

   None.

-Author_and_Institution

   W.L. Taber      (JPL) 
   I.M. Underwood  (JPL) 
   E.D. Wright     (JPL)

-Version

   -CSPICE Version 1.0.0, 08-FEB-1998 (EDW)

-Index_Entries

   radians per degree

-&
*/

 
{ /* Begin rpd_c */

   /*
   Local Variables
   */

   static SpiceDouble  value = 0.;
  

   if ( value == 0. )
      {
      value  =  acos(-1.) / 180.;
      }


   return value;

} /* End rpd_c */

