source: trunk/FACT++/erfa/src/num00a.c@ 18350

Last change on this file since 18350 was 18348, checked in by tbretz, 9 years ago
File size: 5.1 KB
Line 
1#include "erfa.h"
2
3void eraNum00a(double date1, double date2, double rmatn[3][3])
4/*
5** - - - - - - - - - -
6** e r a N u m 0 0 a
7** - - - - - - - - - -
8**
9** Form the matrix of nutation for a given date, IAU 2000A model.
10**
11** Given:
12** date1,date2 double TT as a 2-part Julian Date (Note 1)
13**
14** Returned:
15** rmatn double[3][3] nutation matrix
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 matrix operates in the sense V(true) = rmatn * V(mean), where
39** the p-vector V(true) is with respect to the true equatorial triad
40** of date and the p-vector V(mean) is with respect to the mean
41** equatorial triad of date.
42**
43** 3) A faster, but slightly less accurate result (about 1 mas), can be
44** obtained by using instead the eraNum00b function.
45**
46** Called:
47** eraPn00a bias/precession/nutation, IAU 2000A
48**
49** Reference:
50**
51** Explanatory Supplement to the Astronomical Almanac,
52** P. Kenneth Seidelmann (ed), University Science Books (1992),
53** Section 3.222-3 (p114).
54**
55** Copyright (C) 2013-2015, NumFOCUS Foundation.
56** Derived, with permission, from the SOFA library. See notes at end of file.
57*/
58{
59 double dpsi, deps, epsa, rb[3][3], rp[3][3], rbp[3][3], rbpn[3][3];
60
61/* Obtain the required matrix (discarding other results). */
62 eraPn00a(date1, date2,
63 &dpsi, &deps, &epsa, rb, rp, rbp, rmatn, rbpn);
64
65 return;
66
67}
68/*----------------------------------------------------------------------
69**
70**
71** Copyright (C) 2013-2015, NumFOCUS Foundation.
72** All rights reserved.
73**
74** This library is derived, with permission, from the International
75** Astronomical Union's "Standards of Fundamental Astronomy" library,
76** available from http://www.iausofa.org.
77**
78** The ERFA version is intended to retain identical functionality to
79** the SOFA library, but made distinct through different function and
80** file names, as set out in the SOFA license conditions. The SOFA
81** original has a role as a reference standard for the IAU and IERS,
82** and consequently redistribution is permitted only in its unaltered
83** state. The ERFA version is not subject to this restriction and
84** therefore can be included in distributions which do not support the
85** concept of "read only" software.
86**
87** Although the intent is to replicate the SOFA API (other than
88** replacement of prefix names) and results (with the exception of
89** bugs; any that are discovered will be fixed), SOFA is not
90** responsible for any errors found in this version of the library.
91**
92** If you wish to acknowledge the SOFA heritage, please acknowledge
93** that you are using a library derived from SOFA, rather than SOFA
94** itself.
95**
96**
97** TERMS AND CONDITIONS
98**
99** Redistribution and use in source and binary forms, with or without
100** modification, are permitted provided that the following conditions
101** are met:
102**
103** 1 Redistributions of source code must retain the above copyright
104** notice, this list of conditions and the following disclaimer.
105**
106** 2 Redistributions in binary form must reproduce the above copyright
107** notice, this list of conditions and the following disclaimer in
108** the documentation and/or other materials provided with the
109** distribution.
110**
111** 3 Neither the name of the Standards Of Fundamental Astronomy Board,
112** the International Astronomical Union nor the names of its
113** contributors may be used to endorse or promote products derived
114** from this software without specific prior written permission.
115**
116** THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
117** "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
118** LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
119** FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
120** COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
121** INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
122** BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
123** LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
124** CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
125** LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
126** ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
127** POSSIBILITY OF SUCH DAMAGE.
128**
129*/
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