source: trunk/FACT++/sofa/src/bpn2xy.c@ 18365

Last change on this file since 18365 was 18346, checked in by tbretz, 10 years ago
File size: 5.7 KB
Line 
1#include "sofa.h"
2
3void iauBpn2xy(double rbpn[3][3], double *x, double *y)
4/*
5** - - - - - - - - - -
6** i a u B p n 2 x y
7** - - - - - - - - - -
8**
9** Extract from the bias-precession-nutation matrix the X,Y coordinates
10** of the Celestial Intermediate Pole.
11**
12** This function is part of the International Astronomical Union's
13** SOFA (Standards Of Fundamental Astronomy) software collection.
14**
15** Status: support function.
16**
17** Given:
18** rbpn double[3][3] celestial-to-true matrix (Note 1)
19**
20** Returned:
21** x,y double Celestial Intermediate Pole (Note 2)
22**
23** Notes:
24**
25** 1) The matrix rbpn transforms vectors from GCRS to true equator (and
26** CIO or equinox) of date, and therefore the Celestial Intermediate
27** Pole unit vector is the bottom row of the matrix.
28**
29** 2) The arguments x,y are components of the Celestial Intermediate
30** Pole unit vector in the Geocentric Celestial Reference System.
31**
32** Reference:
33**
34** "Expressions for the Celestial Intermediate Pole and Celestial
35** Ephemeris Origin consistent with the IAU 2000A precession-
36** nutation model", Astron.Astrophys. 400, 1145-1154
37** (2003)
38**
39** n.b. The celestial ephemeris origin (CEO) was renamed "celestial
40** intermediate origin" (CIO) by IAU 2006 Resolution 2.
41**
42** This revision: 2013 June 18
43**
44** SOFA release 2015-02-09
45**
46** Copyright (C) 2015 IAU SOFA Board. See notes at end.
47*/
48{
49/* Extract the X,Y coordinates. */
50 *x = rbpn[2][0];
51 *y = rbpn[2][1];
52
53 return;
54
55/*----------------------------------------------------------------------
56**
57** Copyright (C) 2015
58** Standards Of Fundamental Astronomy Board
59** of the International Astronomical Union.
60**
61** =====================
62** SOFA Software License
63** =====================
64**
65** NOTICE TO USER:
66**
67** BY USING THIS SOFTWARE YOU ACCEPT THE FOLLOWING SIX TERMS AND
68** CONDITIONS WHICH APPLY TO ITS USE.
69**
70** 1. The Software is owned by the IAU SOFA Board ("SOFA").
71**
72** 2. Permission is granted to anyone to use the SOFA software for any
73** purpose, including commercial applications, free of charge and
74** without payment of royalties, subject to the conditions and
75** restrictions listed below.
76**
77** 3. You (the user) may copy and distribute SOFA source code to others,
78** and use and adapt its code and algorithms in your own software,
79** on a world-wide, royalty-free basis. That portion of your
80** distribution that does not consist of intact and unchanged copies
81** of SOFA source code files is a "derived work" that must comply
82** with the following requirements:
83**
84** a) Your work shall be marked or carry a statement that it
85** (i) uses routines and computations derived by you from
86** software provided by SOFA under license to you; and
87** (ii) does not itself constitute software provided by and/or
88** endorsed by SOFA.
89**
90** b) The source code of your derived work must contain descriptions
91** of how the derived work is based upon, contains and/or differs
92** from the original SOFA software.
93**
94** c) The names of all routines in your derived work shall not
95** include the prefix "iau" or "sofa" or trivial modifications
96** thereof such as changes of case.
97**
98** d) The origin of the SOFA components of your derived work must
99** not be misrepresented; you must not claim that you wrote the
100** original software, nor file a patent application for SOFA
101** software or algorithms embedded in the SOFA software.
102**
103** e) These requirements must be reproduced intact in any source
104** distribution and shall apply to anyone to whom you have
105** granted a further right to modify the source code of your
106** derived work.
107**
108** Note that, as originally distributed, the SOFA software is
109** intended to be a definitive implementation of the IAU standards,
110** and consequently third-party modifications are discouraged. All
111** variations, no matter how minor, must be explicitly marked as
112** such, as explained above.
113**
114** 4. You shall not cause the SOFA software to be brought into
115** disrepute, either by misuse, or use for inappropriate tasks, or
116** by inappropriate modification.
117**
118** 5. The SOFA software is provided "as is" and SOFA makes no warranty
119** as to its use or performance. SOFA does not and cannot warrant
120** the performance or results which the user may obtain by using the
121** SOFA software. SOFA makes no warranties, express or implied, as
122** to non-infringement of third party rights, merchantability, or
123** fitness for any particular purpose. In no event will SOFA be
124** liable to the user for any consequential, incidental, or special
125** damages, including any lost profits or lost savings, even if a
126** SOFA representative has been advised of such damages, or for any
127** claim by any third party.
128**
129** 6. The provision of any version of the SOFA software under the terms
130** and conditions specified herein does not imply that future
131** versions will also be made available under the same terms and
132** conditions.
133*
134** In any published work or commercial product which uses the SOFA
135** software directly, acknowledgement (see www.iausofa.org) is
136** appreciated.
137**
138** Correspondence concerning SOFA software should be addressed as
139** follows:
140**
141** By email: sofa@ukho.gov.uk
142** By post: IAU SOFA Center
143** HM Nautical Almanac Office
144** UK Hydrographic Office
145** Admiralty Way, Taunton
146** Somerset, TA1 2DN
147** United Kingdom
148**
149**--------------------------------------------------------------------*/
150}
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