File Coverage

erfasrc/src/obl80.c

Criterion	Covered	Total	%
statement	0	7	0.0
branch			n/a
condition			n/a
subroutine			n/a
pod			n/a
total	0	7	0.0

line	stmt	code
1		#include "erfa.h"
2
3	0	double eraObl80(double date1, double date2)
4		/*
5		** - - - - - - - - -
6		** e r a O b l 8 0
7		** - - - - - - - - -
8		**
9		** Mean obliquity of the ecliptic, IAU 1980 model.
10		**
11		** Given:
12		** date1,date2 double TT as a 2-part Julian Date (Note 1)
13		**
14		** Returned (function value):
15		** double obliquity of the ecliptic (radians, Note 2)
16		**
17		** Notes:
18		**
19		** 1) The TT date date1+date2 is a Julian Date, apportioned in any
20		** convenient way between the two arguments. For example,
21		** JD(TT)=2450123.7 could be expressed in any of these ways,
22		** among others:
23		**
24		** date1 date2
25		**
26		** 2450123.7 0.0 (JD method)
27		** 2451545.0 -1421.3 (J2000 method)
28		** 2400000.5 50123.2 (MJD method)
29		** 2450123.5 0.2 (date & time method)
30		**
31		** The JD method is the most natural and convenient to use in
32		** cases where the loss of several decimal digits of resolution
33		** is acceptable. The J2000 method is best matched to the way
34		** the argument is handled internally and will deliver the
35		** optimum resolution. The MJD method and the date & time methods
36		** are both good compromises between resolution and convenience.
37		**
38		** 2) The result is the angle between the ecliptic and mean equator of
39		** date date1+date2.
40		**
41		** Reference:
42		**
43		** Explanatory Supplement to the Astronomical Almanac,
44		** P. Kenneth Seidelmann (ed), University Science Books (1992),
45		** Expression 3.222-1 (p114).
46		**
47		** Copyright (C) 2013-2020, NumFOCUS Foundation.
48		** Derived, with permission, from the SOFA library. See notes at end of file.
49		*/
50		{
51		double t, eps0;
52
53
54		/* Interval between fundamental epoch J2000.0 and given date (JC). */
55	0	t = ((date1 - ERFA_DJ00) + date2) / ERFA_DJC;
56
57		/* Mean obliquity of date. */
58	0	eps0 = ERFA_DAS2R * (84381.448 +
59	0	(-46.8150 +
60	0	(-0.00059 +
61	0	( 0.001813) * t) * t) * t);
62
63	0	return eps0;
64
65		}
66		/*----------------------------------------------------------------------
67		**
68		**
69		** Copyright (C) 2013-2020, NumFOCUS Foundation.
70		** All rights reserved.
71		**
72		** This library is derived, with permission, from the International
73		** Astronomical Union's "Standards of Fundamental Astronomy" library,
74		** available from http://www.iausofa.org.
75		**
76		** The ERFA version is intended to retain identical functionality to
77		** the SOFA library, but made distinct through different function and
78		** file names, as set out in the SOFA license conditions. The SOFA
79		** original has a role as a reference standard for the IAU and IERS,
80		** and consequently redistribution is permitted only in its unaltered
81		** state. The ERFA version is not subject to this restriction and
82		** therefore can be included in distributions which do not support the
83		** concept of "read only" software.
84		**
85		** Although the intent is to replicate the SOFA API (other than
86		** replacement of prefix names) and results (with the exception of
87		** bugs; any that are discovered will be fixed), SOFA is not
88		** responsible for any errors found in this version of the library.
89		**
90		** If you wish to acknowledge the SOFA heritage, please acknowledge
91		** that you are using a library derived from SOFA, rather than SOFA
92		** itself.
93		**
94		**
95		** TERMS AND CONDITIONS
96		**
97		** Redistribution and use in source and binary forms, with or without
98		** modification, are permitted provided that the following conditions
99		** are met:
100		**
101		** 1 Redistributions of source code must retain the above copyright
102		** notice, this list of conditions and the following disclaimer.
103		**
104		** 2 Redistributions in binary form must reproduce the above copyright
105		** notice, this list of conditions and the following disclaimer in
106		** the documentation and/or other materials provided with the
107		** distribution.
108		**
109		** 3 Neither the name of the Standards Of Fundamental Astronomy Board,
110		** the International Astronomical Union nor the names of its
111		** contributors may be used to endorse or promote products derived
112		** from this software without specific prior written permission.
113		**
114		** THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
115		** "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
116		** LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
117		** FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
118		** COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
119		** INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
120		** BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
121		** LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
122		** CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
123		** LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
124		** ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
125		** POSSIBILITY OF SUCH DAMAGE.
126		**
127		*/