source: trunk/FACT++/sofa/src/num06a.c@ 18368

Last change on this file since 18368 was 18346, checked in by tbretz, 11 years ago
File size: 6.5 KB
Line 
1#include "sofa.h"
2
3void iauNum06a(double date1, double date2, double rmatn[3][3])
4/*
5** - - - - - - - - - -
6** i a u N u m 0 6 a
7** - - - - - - - - - -
8**
9** Form the matrix of nutation for a given date, IAU 2006/2000A model.
10**
11** This function is part of the International Astronomical Union's
12** SOFA (Standards Of Fundamental Astronomy) software collection.
13**
14** Status: support function.
15**
16** Given:
17** date1,date2 double TT as a 2-part Julian Date (Note 1)
18**
19** Returned:
20** rmatn double[3][3] nutation matrix
21**
22** Notes:
23**
24** 1) The TT date date1+date2 is a Julian Date, apportioned in any
25** convenient way between the two arguments. For example,
26** JD(TT)=2450123.7 could be expressed in any of these ways,
27** among others:
28**
29** date1 date2
30**
31** 2450123.7 0.0 (JD method)
32** 2451545.0 -1421.3 (J2000 method)
33** 2400000.5 50123.2 (MJD method)
34** 2450123.5 0.2 (date & time method)
35**
36** The JD method is the most natural and convenient to use in
37** cases where the loss of several decimal digits of resolution
38** is acceptable. The J2000 method is best matched to the way
39** the argument is handled internally and will deliver the
40** optimum resolution. The MJD method and the date & time methods
41** are both good compromises between resolution and convenience.
42**
43** 2) The matrix operates in the sense V(true) = rmatn * V(mean), where
44** the p-vector V(true) is with respect to the true equatorial triad
45** of date and the p-vector V(mean) is with respect to the mean
46** equatorial triad of date.
47**
48** Called:
49** iauObl06 mean obliquity, IAU 2006
50** iauNut06a nutation, IAU 2006/2000A
51** iauNumat form nutation matrix
52**
53** Reference:
54**
55** Explanatory Supplement to the Astronomical Almanac,
56** P. Kenneth Seidelmann (ed), University Science Books (1992),
57** Section 3.222-3 (p114).
58**
59** This revision: 2013 June 18
60**
61** SOFA release 2015-02-09
62**
63** Copyright (C) 2015 IAU SOFA Board. See notes at end.
64*/
65{
66 double eps, dp, de;
67
68/* Mean obliquity. */
69 eps = iauObl06(date1, date2);
70
71/* Nutation components. */
72 iauNut06a(date1, date2, &dp, &de);
73
74/* Nutation matrix. */
75 iauNumat(eps, dp, de, rmatn);
76
77 return;
78
79/*----------------------------------------------------------------------
80**
81** Copyright (C) 2015
82** Standards Of Fundamental Astronomy Board
83** of the International Astronomical Union.
84**
85** =====================
86** SOFA Software License
87** =====================
88**
89** NOTICE TO USER:
90**
91** BY USING THIS SOFTWARE YOU ACCEPT THE FOLLOWING SIX TERMS AND
92** CONDITIONS WHICH APPLY TO ITS USE.
93**
94** 1. The Software is owned by the IAU SOFA Board ("SOFA").
95**
96** 2. Permission is granted to anyone to use the SOFA software for any
97** purpose, including commercial applications, free of charge and
98** without payment of royalties, subject to the conditions and
99** restrictions listed below.
100**
101** 3. You (the user) may copy and distribute SOFA source code to others,
102** and use and adapt its code and algorithms in your own software,
103** on a world-wide, royalty-free basis. That portion of your
104** distribution that does not consist of intact and unchanged copies
105** of SOFA source code files is a "derived work" that must comply
106** with the following requirements:
107**
108** a) Your work shall be marked or carry a statement that it
109** (i) uses routines and computations derived by you from
110** software provided by SOFA under license to you; and
111** (ii) does not itself constitute software provided by and/or
112** endorsed by SOFA.
113**
114** b) The source code of your derived work must contain descriptions
115** of how the derived work is based upon, contains and/or differs
116** from the original SOFA software.
117**
118** c) The names of all routines in your derived work shall not
119** include the prefix "iau" or "sofa" or trivial modifications
120** thereof such as changes of case.
121**
122** d) The origin of the SOFA components of your derived work must
123** not be misrepresented; you must not claim that you wrote the
124** original software, nor file a patent application for SOFA
125** software or algorithms embedded in the SOFA software.
126**
127** e) These requirements must be reproduced intact in any source
128** distribution and shall apply to anyone to whom you have
129** granted a further right to modify the source code of your
130** derived work.
131**
132** Note that, as originally distributed, the SOFA software is
133** intended to be a definitive implementation of the IAU standards,
134** and consequently third-party modifications are discouraged. All
135** variations, no matter how minor, must be explicitly marked as
136** such, as explained above.
137**
138** 4. You shall not cause the SOFA software to be brought into
139** disrepute, either by misuse, or use for inappropriate tasks, or
140** by inappropriate modification.
141**
142** 5. The SOFA software is provided "as is" and SOFA makes no warranty
143** as to its use or performance. SOFA does not and cannot warrant
144** the performance or results which the user may obtain by using the
145** SOFA software. SOFA makes no warranties, express or implied, as
146** to non-infringement of third party rights, merchantability, or
147** fitness for any particular purpose. In no event will SOFA be
148** liable to the user for any consequential, incidental, or special
149** damages, including any lost profits or lost savings, even if a
150** SOFA representative has been advised of such damages, or for any
151** claim by any third party.
152**
153** 6. The provision of any version of the SOFA software under the terms
154** and conditions specified herein does not imply that future
155** versions will also be made available under the same terms and
156** conditions.
157*
158** In any published work or commercial product which uses the SOFA
159** software directly, acknowledgement (see www.iausofa.org) is
160** appreciated.
161**
162** Correspondence concerning SOFA software should be addressed as
163** follows:
164**
165** By email: sofa@ukho.gov.uk
166** By post: IAU SOFA Center
167** HM Nautical Almanac Office
168** UK Hydrographic Office
169** Admiralty Way, Taunton
170** Somerset, TA1 2DN
171** United Kingdom
172**
173**--------------------------------------------------------------------*/
174}
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