source: trunk/FACT++/erfa/src/c2ibpn.c@ 18711

Last change on this file since 18711 was 18711, checked in by tbretz, 9 years ago
Updated to ERFA 1.3.0 (no relevant code change except the leap second at the beginning of 2017)
File size: 6.0 KB
Line 
1#include "erfa.h"
2
3void eraC2ibpn(double date1, double date2, double rbpn[3][3],
4 double rc2i[3][3])
5/*
6** - - - - - - - - - -
7** e r a C 2 i b p n
8** - - - - - - - - - -
9**
10** Form the celestial-to-intermediate matrix for a given date given
11** the bias-precession-nutation matrix. IAU 2000.
12**
13** Given:
14** date1,date2 double TT as a 2-part Julian Date (Note 1)
15** rbpn double[3][3] celestial-to-true matrix (Note 2)
16**
17** Returned:
18** rc2i double[3][3] celestial-to-intermediate matrix (Note 3)
19**
20** Notes:
21**
22** 1) The TT date date1+date2 is a Julian Date, apportioned in any
23** convenient way between the two arguments. For example,
24** JD(TT)=2450123.7 could be expressed in any of these ways,
25** among others:
26**
27** date1 date2
28**
29** 2450123.7 0.0 (JD method)
30** 2451545.0 -1421.3 (J2000 method)
31** 2400000.5 50123.2 (MJD method)
32** 2450123.5 0.2 (date & time method)
33**
34** The JD method is the most natural and convenient to use in
35** cases where the loss of several decimal digits of resolution
36** is acceptable. The J2000 method is best matched to the way
37** the argument is handled internally and will deliver the
38** optimum resolution. The MJD method and the date & time methods
39** are both good compromises between resolution and convenience.
40**
41** 2) The matrix rbpn transforms vectors from GCRS to true equator (and
42** CIO or equinox) of date. Only the CIP (bottom row) is used.
43**
44** 3) The matrix rc2i is the first stage in the transformation from
45** celestial to terrestrial coordinates:
46**
47** [TRS] = RPOM * R_3(ERA) * rc2i * [CRS]
48**
49** = RC2T * [CRS]
50**
51** where [CRS] is a vector in the Geocentric Celestial Reference
52** System and [TRS] is a vector in the International Terrestrial
53** Reference System (see IERS Conventions 2003), ERA is the Earth
54** Rotation Angle and RPOM is the polar motion matrix.
55**
56** 4) Although its name does not include "00", This function is in fact
57** specific to the IAU 2000 models.
58**
59** Called:
60** eraBpn2xy extract CIP X,Y coordinates from NPB matrix
61** eraC2ixy celestial-to-intermediate matrix, given X,Y
62**
63** References:
64** "Expressions for the Celestial Intermediate Pole and Celestial
65** Ephemeris Origin consistent with the IAU 2000A precession-
66** nutation model", Astron.Astrophys. 400, 1145-1154 (2003)
67**
68** n.b. The celestial ephemeris origin (CEO) was renamed "celestial
69** intermediate origin" (CIO) by IAU 2006 Resolution 2.
70**
71** McCarthy, D. D., Petit, G. (eds.), IERS Conventions (2003),
72** IERS Technical Note No. 32, BKG (2004)
73**
74** Copyright (C) 2013-2016, NumFOCUS Foundation.
75** Derived, with permission, from the SOFA library. See notes at end of file.
76*/
77{
78 double x, y;
79
80
81/* Extract the X,Y coordinates. */
82 eraBpn2xy(rbpn, &x, &y);
83
84/* Form the celestial-to-intermediate matrix (n.b. IAU 2000 specific). */
85 eraC2ixy(date1, date2, x, y, rc2i);
86
87 return;
88
89}
90/*----------------------------------------------------------------------
91**
92**
93** Copyright (C) 2013-2016, NumFOCUS Foundation.
94** All rights reserved.
95**
96** This library is derived, with permission, from the International
97** Astronomical Union's "Standards of Fundamental Astronomy" library,
98** available from http://www.iausofa.org.
99**
100** The ERFA version is intended to retain identical functionality to
101** the SOFA library, but made distinct through different function and
102** file names, as set out in the SOFA license conditions. The SOFA
103** original has a role as a reference standard for the IAU and IERS,
104** and consequently redistribution is permitted only in its unaltered
105** state. The ERFA version is not subject to this restriction and
106** therefore can be included in distributions which do not support the
107** concept of "read only" software.
108**
109** Although the intent is to replicate the SOFA API (other than
110** replacement of prefix names) and results (with the exception of
111** bugs; any that are discovered will be fixed), SOFA is not
112** responsible for any errors found in this version of the library.
113**
114** If you wish to acknowledge the SOFA heritage, please acknowledge
115** that you are using a library derived from SOFA, rather than SOFA
116** itself.
117**
118**
119** TERMS AND CONDITIONS
120**
121** Redistribution and use in source and binary forms, with or without
122** modification, are permitted provided that the following conditions
123** are met:
124**
125** 1 Redistributions of source code must retain the above copyright
126** notice, this list of conditions and the following disclaimer.
127**
128** 2 Redistributions in binary form must reproduce the above copyright
129** notice, this list of conditions and the following disclaimer in
130** the documentation and/or other materials provided with the
131** distribution.
132**
133** 3 Neither the name of the Standards Of Fundamental Astronomy Board,
134** the International Astronomical Union nor the names of its
135** contributors may be used to endorse or promote products derived
136** from this software without specific prior written permission.
137**
138** THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
139** "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
140** LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
141** FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
142** COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
143** INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
144** BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
145** LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
146** CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
147** LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
148** ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
149** POSSIBILITY OF SUCH DAMAGE.
150**
151*/
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