source: trunk/FACT++/sofa/src/c2ixy.c@ 18375

Last change on this file since 18375 was 18346, checked in by tbretz, 11 years ago
File size: 7.0 KB
Line 
1#include "sofa.h"
2
3void iauC2ixy(double date1, double date2, double x, double y,
4 double rc2i[3][3])
5/*
6** - - - - - - - - -
7** i a u C 2 i x y
8** - - - - - - - - -
9**
10** Form the celestial to intermediate-frame-of-date matrix for a given
11** date when the CIP X,Y coordinates are known. IAU 2000.
12**
13** This function is part of the International Astronomical Union's
14** SOFA (Standards Of Fundamental Astronomy) software collection.
15**
16** Status: support function.
17**
18** Given:
19** date1,date2 double TT as a 2-part Julian Date (Note 1)
20** x,y double Celestial Intermediate Pole (Note 2)
21**
22** Returned:
23** rc2i double[3][3] celestial-to-intermediate matrix (Note 3)
24**
25** Notes:
26**
27** 1) The TT date date1+date2 is a Julian Date, apportioned in any
28** convenient way between the two arguments. For example,
29** JD(TT)=2450123.7 could be expressed in any of these ways,
30** among others:
31**
32** date1 date2
33**
34** 2450123.7 0.0 (JD method)
35** 2451545.0 -1421.3 (J2000 method)
36** 2400000.5 50123.2 (MJD method)
37** 2450123.5 0.2 (date & time method)
38**
39** The JD method is the most natural and convenient to use in
40** cases where the loss of several decimal digits of resolution
41** is acceptable. The J2000 method is best matched to the way
42** the argument is handled internally and will deliver the
43** optimum resolution. The MJD method and the date & time methods
44** are both good compromises between resolution and convenience.
45**
46** 2) The Celestial Intermediate Pole coordinates are the x,y components
47** of the unit vector in the Geocentric Celestial Reference System.
48**
49** 3) The matrix rc2i is the first stage in the transformation from
50** celestial to terrestrial coordinates:
51**
52** [TRS] = RPOM * R_3(ERA) * rc2i * [CRS]
53**
54** = RC2T * [CRS]
55**
56** where [CRS] is a vector in the Geocentric Celestial Reference
57** System and [TRS] is a vector in the International Terrestrial
58** Reference System (see IERS Conventions 2003), ERA is the Earth
59** Rotation Angle and RPOM is the polar motion matrix.
60**
61** 4) Although its name does not include "00", This function is in fact
62** specific to the IAU 2000 models.
63**
64** Called:
65** iauC2ixys celestial-to-intermediate matrix, given X,Y and s
66** iauS00 the CIO locator s, given X,Y, IAU 2000A
67**
68** Reference:
69**
70** McCarthy, D. D., Petit, G. (eds.), IERS Conventions (2003),
71** IERS Technical Note No. 32, BKG (2004)
72**
73** This revision: 2013 June 18
74**
75** SOFA release 2015-02-09
76**
77** Copyright (C) 2015 IAU SOFA Board. See notes at end.
78*/
79
80{
81/* Compute s and then the matrix. */
82 iauC2ixys(x, y, iauS00(date1, date2, x, y), rc2i);
83
84 return;
85
86/*----------------------------------------------------------------------
87**
88** Copyright (C) 2015
89** Standards Of Fundamental Astronomy Board
90** of the International Astronomical Union.
91**
92** =====================
93** SOFA Software License
94** =====================
95**
96** NOTICE TO USER:
97**
98** BY USING THIS SOFTWARE YOU ACCEPT THE FOLLOWING SIX TERMS AND
99** CONDITIONS WHICH APPLY TO ITS USE.
100**
101** 1. The Software is owned by the IAU SOFA Board ("SOFA").
102**
103** 2. Permission is granted to anyone to use the SOFA software for any
104** purpose, including commercial applications, free of charge and
105** without payment of royalties, subject to the conditions and
106** restrictions listed below.
107**
108** 3. You (the user) may copy and distribute SOFA source code to others,
109** and use and adapt its code and algorithms in your own software,
110** on a world-wide, royalty-free basis. That portion of your
111** distribution that does not consist of intact and unchanged copies
112** of SOFA source code files is a "derived work" that must comply
113** with the following requirements:
114**
115** a) Your work shall be marked or carry a statement that it
116** (i) uses routines and computations derived by you from
117** software provided by SOFA under license to you; and
118** (ii) does not itself constitute software provided by and/or
119** endorsed by SOFA.
120**
121** b) The source code of your derived work must contain descriptions
122** of how the derived work is based upon, contains and/or differs
123** from the original SOFA software.
124**
125** c) The names of all routines in your derived work shall not
126** include the prefix "iau" or "sofa" or trivial modifications
127** thereof such as changes of case.
128**
129** d) The origin of the SOFA components of your derived work must
130** not be misrepresented; you must not claim that you wrote the
131** original software, nor file a patent application for SOFA
132** software or algorithms embedded in the SOFA software.
133**
134** e) These requirements must be reproduced intact in any source
135** distribution and shall apply to anyone to whom you have
136** granted a further right to modify the source code of your
137** derived work.
138**
139** Note that, as originally distributed, the SOFA software is
140** intended to be a definitive implementation of the IAU standards,
141** and consequently third-party modifications are discouraged. All
142** variations, no matter how minor, must be explicitly marked as
143** such, as explained above.
144**
145** 4. You shall not cause the SOFA software to be brought into
146** disrepute, either by misuse, or use for inappropriate tasks, or
147** by inappropriate modification.
148**
149** 5. The SOFA software is provided "as is" and SOFA makes no warranty
150** as to its use or performance. SOFA does not and cannot warrant
151** the performance or results which the user may obtain by using the
152** SOFA software. SOFA makes no warranties, express or implied, as
153** to non-infringement of third party rights, merchantability, or
154** fitness for any particular purpose. In no event will SOFA be
155** liable to the user for any consequential, incidental, or special
156** damages, including any lost profits or lost savings, even if a
157** SOFA representative has been advised of such damages, or for any
158** claim by any third party.
159**
160** 6. The provision of any version of the SOFA software under the terms
161** and conditions specified herein does not imply that future
162** versions will also be made available under the same terms and
163** conditions.
164*
165** In any published work or commercial product which uses the SOFA
166** software directly, acknowledgement (see www.iausofa.org) is
167** appreciated.
168**
169** Correspondence concerning SOFA software should be addressed as
170** follows:
171**
172** By email: sofa@ukho.gov.uk
173** By post: IAU SOFA Center
174** HM Nautical Almanac Office
175** UK Hydrographic Office
176** Admiralty Way, Taunton
177** Somerset, TA1 2DN
178** United Kingdom
179**
180**--------------------------------------------------------------------*/
181}
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