source: trunk/FACT++/sofa/src/num00a.c@ 18375

Last change on this file since 18375 was 18346, checked in by tbretz, 11 years ago
File size: 6.6 KB
Line 
1#include "sofa.h"
2
3void iauNum00a(double date1, double date2, double rmatn[3][3])
4/*
5** - - - - - - - - - -
6** i a u N u m 0 0 a
7** - - - - - - - - - -
8**
9** Form the matrix of nutation for a given date, IAU 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** 3) A faster, but slightly less accurate result (about 1 mas), can be
49** obtained by using instead the iauNum00b function.
50**
51** Called:
52** iauPn00a bias/precession/nutation, IAU 2000A
53**
54** Reference:
55**
56** Explanatory Supplement to the Astronomical Almanac,
57** P. Kenneth Seidelmann (ed), University Science Books (1992),
58** Section 3.222-3 (p114).
59**
60** This revision: 2013 June 18
61**
62** SOFA release 2015-02-09
63**
64** Copyright (C) 2015 IAU SOFA Board. See notes at end.
65*/
66{
67 double dpsi, deps, epsa, rb[3][3], rp[3][3], rbp[3][3], rbpn[3][3];
68
69/* Obtain the required matrix (discarding other results). */
70 iauPn00a(date1, date2,
71 &dpsi, &deps, &epsa, rb, rp, rbp, rmatn, rbpn);
72
73 return;
74
75/*----------------------------------------------------------------------
76**
77** Copyright (C) 2015
78** Standards Of Fundamental Astronomy Board
79** of the International Astronomical Union.
80**
81** =====================
82** SOFA Software License
83** =====================
84**
85** NOTICE TO USER:
86**
87** BY USING THIS SOFTWARE YOU ACCEPT THE FOLLOWING SIX TERMS AND
88** CONDITIONS WHICH APPLY TO ITS USE.
89**
90** 1. The Software is owned by the IAU SOFA Board ("SOFA").
91**
92** 2. Permission is granted to anyone to use the SOFA software for any
93** purpose, including commercial applications, free of charge and
94** without payment of royalties, subject to the conditions and
95** restrictions listed below.
96**
97** 3. You (the user) may copy and distribute SOFA source code to others,
98** and use and adapt its code and algorithms in your own software,
99** on a world-wide, royalty-free basis. That portion of your
100** distribution that does not consist of intact and unchanged copies
101** of SOFA source code files is a "derived work" that must comply
102** with the following requirements:
103**
104** a) Your work shall be marked or carry a statement that it
105** (i) uses routines and computations derived by you from
106** software provided by SOFA under license to you; and
107** (ii) does not itself constitute software provided by and/or
108** endorsed by SOFA.
109**
110** b) The source code of your derived work must contain descriptions
111** of how the derived work is based upon, contains and/or differs
112** from the original SOFA software.
113**
114** c) The names of all routines in your derived work shall not
115** include the prefix "iau" or "sofa" or trivial modifications
116** thereof such as changes of case.
117**
118** d) The origin of the SOFA components of your derived work must
119** not be misrepresented; you must not claim that you wrote the
120** original software, nor file a patent application for SOFA
121** software or algorithms embedded in the SOFA software.
122**
123** e) These requirements must be reproduced intact in any source
124** distribution and shall apply to anyone to whom you have
125** granted a further right to modify the source code of your
126** derived work.
127**
128** Note that, as originally distributed, the SOFA software is
129** intended to be a definitive implementation of the IAU standards,
130** and consequently third-party modifications are discouraged. All
131** variations, no matter how minor, must be explicitly marked as
132** such, as explained above.
133**
134** 4. You shall not cause the SOFA software to be brought into
135** disrepute, either by misuse, or use for inappropriate tasks, or
136** by inappropriate modification.
137**
138** 5. The SOFA software is provided "as is" and SOFA makes no warranty
139** as to its use or performance. SOFA does not and cannot warrant
140** the performance or results which the user may obtain by using the
141** SOFA software. SOFA makes no warranties, express or implied, as
142** to non-infringement of third party rights, merchantability, or
143** fitness for any particular purpose. In no event will SOFA be
144** liable to the user for any consequential, incidental, or special
145** damages, including any lost profits or lost savings, even if a
146** SOFA representative has been advised of such damages, or for any
147** claim by any third party.
148**
149** 6. The provision of any version of the SOFA software under the terms
150** and conditions specified herein does not imply that future
151** versions will also be made available under the same terms and
152** conditions.
153*
154** In any published work or commercial product which uses the SOFA
155** software directly, acknowledgement (see www.iausofa.org) is
156** appreciated.
157**
158** Correspondence concerning SOFA software should be addressed as
159** follows:
160**
161** By email: sofa@ukho.gov.uk
162** By post: IAU SOFA Center
163** HM Nautical Almanac Office
164** UK Hydrographic Office
165** Admiralty Way, Taunton
166** Somerset, TA1 2DN
167** United Kingdom
168**
169**--------------------------------------------------------------------*/
170}
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