source: trunk/FACT++/sofa/src/pom00.c@ 18365

Last change on this file since 18365 was 18346, checked in by tbretz, 10 years ago
File size: 6.3 KB
Line 
1#include "sofa.h"
2
3void iauPom00(double xp, double yp, double sp, double rpom[3][3])
4/*
5** - - - - - - - - - -
6** i a u P o m 0 0
7** - - - - - - - - - -
8**
9** Form the matrix of polar motion for a given date, IAU 2000.
10**
11** This function is part of the International Astronomical Union's
12** SOFA (Standards Of Fundamental Astronomy) software collection.
13**
14** Status: support function.
15**
16** Given:
17** xp,yp double coordinates of the pole (radians, Note 1)
18** sp double the TIO locator s' (radians, Note 2)
19**
20** Returned:
21** rpom double[3][3] polar-motion matrix (Note 3)
22**
23** Notes:
24**
25** 1) The arguments xp and yp are the coordinates (in radians) of the
26** Celestial Intermediate Pole with respect to the International
27** Terrestrial Reference System (see IERS Conventions 2003),
28** measured along the meridians to 0 and 90 deg west respectively.
29**
30** 2) The argument sp is the TIO locator s', in radians, which
31** positions the Terrestrial Intermediate Origin on the equator. It
32** is obtained from polar motion observations by numerical
33** integration, and so is in essence unpredictable. However, it is
34** dominated by a secular drift of about 47 microarcseconds per
35** century, and so can be taken into account by using s' = -47*t,
36** where t is centuries since J2000.0. The function iauSp00
37** implements this approximation.
38**
39** 3) The matrix operates in the sense V(TRS) = rpom * V(CIP), meaning
40** that it is the final rotation when computing the pointing
41** direction to a celestial source.
42**
43** Called:
44** iauIr initialize r-matrix to identity
45** iauRz rotate around Z-axis
46** iauRy rotate around Y-axis
47** iauRx rotate around X-axis
48**
49** Reference:
50**
51** McCarthy, D. D., Petit, G. (eds.), IERS Conventions (2003),
52** IERS Technical Note No. 32, BKG (2004)
53**
54** This revision: 2013 June 18
55**
56** SOFA release 2015-02-09
57**
58** Copyright (C) 2015 IAU SOFA Board. See notes at end.
59*/
60{
61
62/* Construct the matrix. */
63 iauIr(rpom);
64 iauRz(sp, rpom);
65 iauRy(-xp, rpom);
66 iauRx(-yp, rpom);
67
68 return;
69
70/*----------------------------------------------------------------------
71**
72** Copyright (C) 2015
73** Standards Of Fundamental Astronomy Board
74** of the International Astronomical Union.
75**
76** =====================
77** SOFA Software License
78** =====================
79**
80** NOTICE TO USER:
81**
82** BY USING THIS SOFTWARE YOU ACCEPT THE FOLLOWING SIX TERMS AND
83** CONDITIONS WHICH APPLY TO ITS USE.
84**
85** 1. The Software is owned by the IAU SOFA Board ("SOFA").
86**
87** 2. Permission is granted to anyone to use the SOFA software for any
88** purpose, including commercial applications, free of charge and
89** without payment of royalties, subject to the conditions and
90** restrictions listed below.
91**
92** 3. You (the user) may copy and distribute SOFA source code to others,
93** and use and adapt its code and algorithms in your own software,
94** on a world-wide, royalty-free basis. That portion of your
95** distribution that does not consist of intact and unchanged copies
96** of SOFA source code files is a "derived work" that must comply
97** with the following requirements:
98**
99** a) Your work shall be marked or carry a statement that it
100** (i) uses routines and computations derived by you from
101** software provided by SOFA under license to you; and
102** (ii) does not itself constitute software provided by and/or
103** endorsed by SOFA.
104**
105** b) The source code of your derived work must contain descriptions
106** of how the derived work is based upon, contains and/or differs
107** from the original SOFA software.
108**
109** c) The names of all routines in your derived work shall not
110** include the prefix "iau" or "sofa" or trivial modifications
111** thereof such as changes of case.
112**
113** d) The origin of the SOFA components of your derived work must
114** not be misrepresented; you must not claim that you wrote the
115** original software, nor file a patent application for SOFA
116** software or algorithms embedded in the SOFA software.
117**
118** e) These requirements must be reproduced intact in any source
119** distribution and shall apply to anyone to whom you have
120** granted a further right to modify the source code of your
121** derived work.
122**
123** Note that, as originally distributed, the SOFA software is
124** intended to be a definitive implementation of the IAU standards,
125** and consequently third-party modifications are discouraged. All
126** variations, no matter how minor, must be explicitly marked as
127** such, as explained above.
128**
129** 4. You shall not cause the SOFA software to be brought into
130** disrepute, either by misuse, or use for inappropriate tasks, or
131** by inappropriate modification.
132**
133** 5. The SOFA software is provided "as is" and SOFA makes no warranty
134** as to its use or performance. SOFA does not and cannot warrant
135** the performance or results which the user may obtain by using the
136** SOFA software. SOFA makes no warranties, express or implied, as
137** to non-infringement of third party rights, merchantability, or
138** fitness for any particular purpose. In no event will SOFA be
139** liable to the user for any consequential, incidental, or special
140** damages, including any lost profits or lost savings, even if a
141** SOFA representative has been advised of such damages, or for any
142** claim by any third party.
143**
144** 6. The provision of any version of the SOFA software under the terms
145** and conditions specified herein does not imply that future
146** versions will also be made available under the same terms and
147** conditions.
148*
149** In any published work or commercial product which uses the SOFA
150** software directly, acknowledgement (see www.iausofa.org) is
151** appreciated.
152**
153** Correspondence concerning SOFA software should be addressed as
154** follows:
155**
156** By email: sofa@ukho.gov.uk
157** By post: IAU SOFA Center
158** HM Nautical Almanac Office
159** UK Hydrographic Office
160** Admiralty Way, Taunton
161** Somerset, TA1 2DN
162** United Kingdom
163**
164**--------------------------------------------------------------------*/
165}
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