source: branches/FACT++_lidctrl_usb/erfa/src/c2i00a.c@ 19875

Last change on this file since 19875 was 18711, checked in by tbretz, 10 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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