source: branches/FACT++_lidctrl_usb/erfa/src/c2i06a.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: 5.6 KB
Line 
1#include "erfa.h"
2
3void eraC2i06a(double date1, double date2, double rc2i[3][3])
4/*
5** - - - - - - - - - -
6** e r a C 2 i 0 6 a
7** - - - - - - - - - -
8**
9** Form the celestial-to-intermediate matrix for a given date using the
10** IAU 2006 precession and IAU 2000A nutation models.
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** Called:
52** eraPnm06a classical NPB matrix, IAU 2006/2000A
53** eraBpn2xy extract CIP X,Y coordinates from NPB matrix
54** eraS06 the CIO locator s, given X,Y, IAU 2006
55** eraC2ixys celestial-to-intermediate matrix, given X,Y and s
56**
57** References:
58**
59** McCarthy, D. D., Petit, G. (eds.), 2004, IERS Conventions (2003),
60** IERS Technical Note No. 32, BKG
61**
62** Copyright (C) 2013-2016, NumFOCUS Foundation.
63** Derived, with permission, from the SOFA library. See notes at end of file.
64*/
65{
66 double rbpn[3][3], x, y, s;
67
68
69/* Obtain the celestial-to-true matrix (IAU 2006/2000A). */
70 eraPnm06a(date1, date2, rbpn);
71
72/* Extract the X,Y coordinates. */
73 eraBpn2xy(rbpn, &x, &y);
74
75/* Obtain the CIO locator. */
76 s = eraS06(date1, date2, x, y);
77
78/* Form the celestial-to-intermediate matrix. */
79 eraC2ixys(x, y, s, rc2i);
80
81 return;
82
83}
84/*----------------------------------------------------------------------
85**
86**
87** Copyright (C) 2013-2016, NumFOCUS Foundation.
88** All rights reserved.
89**
90** This library is derived, with permission, from the International
91** Astronomical Union's "Standards of Fundamental Astronomy" library,
92** available from http://www.iausofa.org.
93**
94** The ERFA version is intended to retain identical functionality to
95** the SOFA library, but made distinct through different function and
96** file names, as set out in the SOFA license conditions. The SOFA
97** original has a role as a reference standard for the IAU and IERS,
98** and consequently redistribution is permitted only in its unaltered
99** state. The ERFA version is not subject to this restriction and
100** therefore can be included in distributions which do not support the
101** concept of "read only" software.
102**
103** Although the intent is to replicate the SOFA API (other than
104** replacement of prefix names) and results (with the exception of
105** bugs; any that are discovered will be fixed), SOFA is not
106** responsible for any errors found in this version of the library.
107**
108** If you wish to acknowledge the SOFA heritage, please acknowledge
109** that you are using a library derived from SOFA, rather than SOFA
110** itself.
111**
112**
113** TERMS AND CONDITIONS
114**
115** Redistribution and use in source and binary forms, with or without
116** modification, are permitted provided that the following conditions
117** are met:
118**
119** 1 Redistributions of source code must retain the above copyright
120** notice, this list of conditions and the following disclaimer.
121**
122** 2 Redistributions in binary form must reproduce the above copyright
123** notice, this list of conditions and the following disclaimer in
124** the documentation and/or other materials provided with the
125** distribution.
126**
127** 3 Neither the name of the Standards Of Fundamental Astronomy Board,
128** the International Astronomical Union nor the names of its
129** contributors may be used to endorse or promote products derived
130** from this software without specific prior written permission.
131**
132** THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
133** "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
134** LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
135** FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
136** COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
137** INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
138** BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
139** LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
140** CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
141** LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
142** ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
143** POSSIBILITY OF SUCH DAMAGE.
144**
145*/
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