source: trunk/FACT++/erfa/src/ee00.c@ 18348

Last change on this file since 18348 was 18348, checked in by tbretz, 9 years ago
File size: 5.3 KB
Line 
1#include "erfa.h"
2
3double eraEe00(double date1, double date2, double epsa, double dpsi)
4/*
5** - - - - - - - -
6** e r a E e 0 0
7** - - - - - - - -
8**
9** The equation of the equinoxes, compatible with IAU 2000 resolutions,
10** given the nutation in longitude and the mean obliquity.
11**
12** Given:
13** date1,date2 double TT as a 2-part Julian Date (Note 1)
14** epsa double mean obliquity (Note 2)
15** dpsi double nutation in longitude (Note 3)
16**
17** Returned (function value):
18** double equation of the equinoxes (Note 4)
19**
20** Notes:
21**
22** 1) The TT date date1+date2 is a Julian Date, apportioned in any
23** convenient way between the two arguments. For example,
24** JD(TT)=2450123.7 could be expressed in any of these ways,
25** among others:
26**
27** date1 date2
28**
29** 2450123.7 0.0 (JD method)
30** 2451545.0 -1421.3 (J2000 method)
31** 2400000.5 50123.2 (MJD method)
32** 2450123.5 0.2 (date & time method)
33**
34** The JD method is the most natural and convenient to use in
35** cases where the loss of several decimal digits of resolution
36** is acceptable. The J2000 method is best matched to the way
37** the argument is handled internally and will deliver the
38** optimum resolution. The MJD method and the date & time methods
39** are both good compromises between resolution and convenience.
40**
41** 2) The obliquity, in radians, is mean of date.
42**
43** 3) The result, which is in radians, operates in the following sense:
44**
45** Greenwich apparent ST = GMST + equation of the equinoxes
46**
47** 4) The result is compatible with the IAU 2000 resolutions. For
48** further details, see IERS Conventions 2003 and Capitaine et al.
49** (2002).
50**
51** Called:
52** eraEect00 equation of the equinoxes complementary terms
53**
54** References:
55**
56** Capitaine, N., Wallace, P.T. and McCarthy, D.D., "Expressions to
57** implement the IAU 2000 definition of UT1", Astronomy &
58** Astrophysics, 406, 1135-1149 (2003)
59**
60** McCarthy, D. D., Petit, G. (eds.), IERS Conventions (2003),
61** IERS Technical Note No. 32, BKG (2004)
62**
63** Copyright (C) 2013-2015, NumFOCUS Foundation.
64** Derived, with permission, from the SOFA library. See notes at end of file.
65*/
66{
67 double ee;
68
69/* Equation of the equinoxes. */
70 ee = dpsi * cos(epsa) + eraEect00(date1, date2);
71
72 return ee;
73
74}
75/*----------------------------------------------------------------------
76**
77**
78** Copyright (C) 2013-2015, NumFOCUS Foundation.
79** All rights reserved.
80**
81** This library is derived, with permission, from the International
82** Astronomical Union's "Standards of Fundamental Astronomy" library,
83** available from http://www.iausofa.org.
84**
85** The ERFA version is intended to retain identical functionality to
86** the SOFA library, but made distinct through different function and
87** file names, as set out in the SOFA license conditions. The SOFA
88** original has a role as a reference standard for the IAU and IERS,
89** and consequently redistribution is permitted only in its unaltered
90** state. The ERFA version is not subject to this restriction and
91** therefore can be included in distributions which do not support the
92** concept of "read only" software.
93**
94** Although the intent is to replicate the SOFA API (other than
95** replacement of prefix names) and results (with the exception of
96** bugs; any that are discovered will be fixed), SOFA is not
97** responsible for any errors found in this version of the library.
98**
99** If you wish to acknowledge the SOFA heritage, please acknowledge
100** that you are using a library derived from SOFA, rather than SOFA
101** itself.
102**
103**
104** TERMS AND CONDITIONS
105**
106** Redistribution and use in source and binary forms, with or without
107** modification, are permitted provided that the following conditions
108** are met:
109**
110** 1 Redistributions of source code must retain the above copyright
111** notice, this list of conditions and the following disclaimer.
112**
113** 2 Redistributions in binary form must reproduce the above copyright
114** notice, this list of conditions and the following disclaimer in
115** the documentation and/or other materials provided with the
116** distribution.
117**
118** 3 Neither the name of the Standards Of Fundamental Astronomy Board,
119** the International Astronomical Union nor the names of its
120** contributors may be used to endorse or promote products derived
121** from this software without specific prior written permission.
122**
123** THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
124** "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
125** LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
126** FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
127** COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
128** INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
129** BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
130** LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
131** CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
132** LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
133** ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
134** POSSIBILITY OF SUCH DAMAGE.
135**
136*/
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