source: branches/FACT++_part_filenames/erfa/src/c2i00a.c@ 19894

Last change on this file since 19894 was 18711, checked in by tbretz, 8 years ago
Updated to ERFA 1.3.0 (no relevant code change except the leap second at the beginning of 2017)
File size: 5.8 KB
Line 
1#include "erfa.h"
2
3void eraC2i00a(double date1, double date2, double rc2i[3][3])
4/*
5** - - - - - - - - - -
6** e r a C 2 i 0 0 a
7** - - - - - - - - - -
8**
9** Form the celestial-to-intermediate matrix for a given date using the
10** IAU 2000A precession-nutation model.
11**
12** Given:
13** date1,date2 double TT as a 2-part Julian Date (Note 1)
14**
15** Returned:
16** rc2i double[3][3] celestial-to-intermediate matrix (Note 2)
17**
18** Notes:
19**
20** 1) The TT date date1+date2 is a Julian Date, apportioned in any
21** convenient way between the two arguments. For example,
22** JD(TT)=2450123.7 could be expressed in any of these ways,
23** among others:
24**
25** date1 date2
26**
27** 2450123.7 0.0 (JD method)
28** 2451545.0 -1421.3 (J2000 method)
29** 2400000.5 50123.2 (MJD method)
30** 2450123.5 0.2 (date & time method)
31**
32** The JD method is the most natural and convenient to use in
33** cases where the loss of several decimal digits of resolution
34** is acceptable. The J2000 method is best matched to the way
35** the argument is handled internally and will deliver the
36** optimum resolution. The MJD method and the date & time methods
37** are both good compromises between resolution and convenience.
38**
39** 2) The matrix rc2i is the first stage in the transformation from
40** celestial to terrestrial coordinates:
41**
42** [TRS] = RPOM * R_3(ERA) * rc2i * [CRS]
43**
44** = rc2t * [CRS]
45**
46** where [CRS] is a vector in the Geocentric Celestial Reference
47** System and [TRS] is a vector in the International Terrestrial
48** Reference System (see IERS Conventions 2003), ERA is the Earth
49** Rotation Angle and RPOM is the polar motion matrix.
50**
51** 3) A faster, but slightly less accurate result (about 1 mas), can be
52** obtained by using instead the eraC2i00b function.
53**
54** Called:
55** eraPnm00a classical NPB matrix, IAU 2000A
56** eraC2ibpn celestial-to-intermediate matrix, given NPB matrix
57**
58** References:
59**
60** "Expressions for the Celestial Intermediate Pole and Celestial
61** Ephemeris Origin consistent with the IAU 2000A precession-
62** nutation model", Astron.Astrophys. 400, 1145-1154
63** (2003)
64**
65** n.b. The celestial ephemeris origin (CEO) was renamed "celestial
66** intermediate origin" (CIO) by IAU 2006 Resolution 2.
67**
68** McCarthy, D. D., Petit, G. (eds.), IERS Conventions (2003),
69** IERS Technical Note No. 32, BKG (2004)
70**
71** Copyright (C) 2013-2016, NumFOCUS Foundation.
72** Derived, with permission, from the SOFA library. See notes at end of file.
73*/
74{
75 double rbpn[3][3];
76
77
78/* Obtain the celestial-to-true matrix (IAU 2000A). */
79 eraPnm00a(date1, date2, rbpn);
80
81/* Form the celestial-to-intermediate matrix. */
82 eraC2ibpn(date1, date2, rbpn, rc2i);
83
84 return;
85
86}
87/*----------------------------------------------------------------------
88**
89**
90** Copyright (C) 2013-2016, NumFOCUS Foundation.
91** All rights reserved.
92**
93** This library is derived, with permission, from the International
94** Astronomical Union's "Standards of Fundamental Astronomy" library,
95** available from http://www.iausofa.org.
96**
97** The ERFA version is intended to retain identical functionality to
98** the SOFA library, but made distinct through different function and
99** file names, as set out in the SOFA license conditions. The SOFA
100** original has a role as a reference standard for the IAU and IERS,
101** and consequently redistribution is permitted only in its unaltered
102** state. The ERFA version is not subject to this restriction and
103** therefore can be included in distributions which do not support the
104** concept of "read only" software.
105**
106** Although the intent is to replicate the SOFA API (other than
107** replacement of prefix names) and results (with the exception of
108** bugs; any that are discovered will be fixed), SOFA is not
109** responsible for any errors found in this version of the library.
110**
111** If you wish to acknowledge the SOFA heritage, please acknowledge
112** that you are using a library derived from SOFA, rather than SOFA
113** itself.
114**
115**
116** TERMS AND CONDITIONS
117**
118** Redistribution and use in source and binary forms, with or without
119** modification, are permitted provided that the following conditions
120** are met:
121**
122** 1 Redistributions of source code must retain the above copyright
123** notice, this list of conditions and the following disclaimer.
124**
125** 2 Redistributions in binary form must reproduce the above copyright
126** notice, this list of conditions and the following disclaimer in
127** the documentation and/or other materials provided with the
128** distribution.
129**
130** 3 Neither the name of the Standards Of Fundamental Astronomy Board,
131** the International Astronomical Union nor the names of its
132** contributors may be used to endorse or promote products derived
133** from this software without specific prior written permission.
134**
135** THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
136** "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
137** LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
138** FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
139** COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
140** INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
141** BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
142** LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
143** CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
144** LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
145** ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
146** POSSIBILITY OF SUCH DAMAGE.
147**
148*/
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