1 /*
2 
3 -Procedure tyear_c ( Seconds per tropical year )
4 
5 -Abstract
6 
7    Return the number of seconds in a tropical year.
8 
9 -Disclaimer
10 
11    THIS SOFTWARE AND ANY RELATED MATERIALS WERE CREATED BY THE
12    CALIFORNIA INSTITUTE OF TECHNOLOGY (CALTECH) UNDER A U.S.
13    GOVERNMENT CONTRACT WITH THE NATIONAL AERONAUTICS AND SPACE
14    ADMINISTRATION (NASA). THE SOFTWARE IS TECHNOLOGY AND SOFTWARE
15    PUBLICLY AVAILABLE UNDER U.S. EXPORT LAWS AND IS PROVIDED "AS-IS"
16    TO THE RECIPIENT WITHOUT WARRANTY OF ANY KIND, INCLUDING ANY
17    WARRANTIES OF PERFORMANCE OR MERCHANTABILITY OR FITNESS FOR A
18    PARTICULAR USE OR PURPOSE (AS SET FORTH IN UNITED STATES UCC
19    SECTIONS 2312-2313) OR FOR ANY PURPOSE WHATSOEVER, FOR THE
20    SOFTWARE AND RELATED MATERIALS, HOWEVER USED.
21 
22    IN NO EVENT SHALL CALTECH, ITS JET PROPULSION LABORATORY, OR NASA
23    BE LIABLE FOR ANY DAMAGES AND/OR COSTS, INCLUDING, BUT NOT
24    LIMITED TO, INCIDENTAL OR CONSEQUENTIAL DAMAGES OF ANY KIND,
25    INCLUDING ECONOMIC DAMAGE OR INJURY TO PROPERTY AND LOST PROFITS,
26    REGARDLESS OF WHETHER CALTECH, JPL, OR NASA BE ADVISED, HAVE
27    REASON TO KNOW, OR, IN FACT, SHALL KNOW OF THE POSSIBILITY.
28 
29    RECIPIENT BEARS ALL RISK RELATING TO QUALITY AND PERFORMANCE OF
30    THE SOFTWARE AND ANY RELATED MATERIALS, AND AGREES TO INDEMNIFY
31    CALTECH AND NASA FOR ALL THIRD-PARTY CLAIMS RESULTING FROM THE
32    ACTIONS OF RECIPIENT IN THE USE OF THE SOFTWARE.
33 
34 -Required_Reading
35 
36 None.
37 
38 -Keywords
39 
40    CONSTANTS
41 
42 */
43 
44    #include "SpiceUsr.h"
45 
tyear_c(void)46    SpiceDouble tyear_c ( void )
47 
48 /*
49 
50 -Brief_I/O
51 
52    VARIABLE  I/O              DESCRIPTION
53    --------  ---  --------------------------------------------------
54    tyear_c       O   The number of seconds/tropical year
55 
56 -Detailed_Input
57 
58    None.
59 
60 -Detailed_Output
61 
62    The function returns the number of seconds per tropical
63    year.  This value is taken from the 1992 Explanatory Supplement
64    to the Astronomical Almanac.
65 
66 -Parameters
67 
68    None.
69 
70 -Particulars
71 
72    The tropical year is often used as a fundamental unit
73    of time when dealing with older ephemeris data.  For this
74    reason its value in terms of ephemeris seconds is
75    recorded in this function.
76 
77 -Examples
78 
79    Suppose you wish to compute the number of tropical centuries
80    that have elapsed since the ephemeris epoch B1950 (beginning
81    of the Besselian year 1950) at a particular ET epoch.  The
82    following line of code will do the trick.
83 
84 
85       century = ( et - unitim_ ( b1950_c(), "JED", "ET" ) )
86                 / ( 100.0 * tyear_c() );
87 
88 
89 -Restrictions
90 
91     None.
92 
93 -Exceptions
94 
95    Error free.
96 
97 -Files
98 
99    None.
100 
101 -Author_and_Institution
102 
103    W.L. Taber      (JPL)
104    E.D. Wright     (JPL)
105 
106 -Literature_References
107 
108    Explanatory Supplement to the Astronomical Almanac.
109    Page 80. University Science Books, 20 Edgehill Road,
110    Mill Valley, CA 94941
111 
112 -Version
113 
114    -CSPICE Version 1.0.0, 08-FEB-1998 (EDW)
115 
116 -Index_Entries
117 
118    Number of seconds per tropical year
119 
120 -&
121 */
122 
123 { /* Begin tyear_c */
124 
125    return 31556925.9747;
126 
127 } /* End tyear_c */
128