/*

-Procedure tyear_c ( Seconds per tropical year )

-Abstract
 
   Return the number of seconds in a tropical year. 
 
-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 "SpiceUsr.h"

   SpiceDouble tyear_c ( void ) 

/*

-Brief_I/O
 
   VARIABLE  I/O              DESCRIPTION 
   --------  ---  -------------------------------------------------- 
   tyear_c       O   The number of seconds/tropical year 
 
-Detailed_Input
 
   None. 
 
-Detailed_Output
 
   The function returns the number of seconds per tropical 
   year.  This value is taken from the 1992 Explanatory Supplement 
   to the Astronomical Almanac. 
 
-Parameters
 
   None. 
 
-Particulars
 
   The tropical year is often used as a fundamental unit 
   of time when dealing with older ephemeris data.  For this 
   reason its value in terms of ephemeris seconds is 
   recorded in this function. 
 
-Examples
 
   Suppose you wish to compute the number of tropical centuries 
   that have elapsed since the ephemeris epoch B1950 (beginning 
   of the Besselian year 1950) at a particular ET epoch.  The 
   following line of code will do the trick. 
 
 
      century = ( et - unitim_ ( b1950_c(), "JED", "ET" ) ) 
                / ( 100.0 * tyear_c() );
 
 
-Restrictions
 
    None. 
 
-Exceptions
 
   Error free. 
 
-Files
 
   None. 
 
-Author_and_Institution
 
   W.L. Taber      (JPL) 
   E.D. Wright     (JPL)
 
-Literature_References
 
   Explanatory Supplement to the Astronomical Almanac. 
   Page 80. University Science Books, 20 Edgehill Road, 
   Mill Valley, CA 94941 
 
-Version

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

-Index_Entries
 
   Number of seconds per tropical year 
 
-&
*/

{ /* Begin tyear_c */

   return 31556925.9747;

} /* End tyear_c */
