source: trunk/FACT++/erfa/src/bpn2xy.c@ 18403

Last change on this file since 18403 was 18348, checked in by tbretz, 9 years ago
File size: 4.3 KB
Line 
1#include "erfa.h"
2
3void eraBpn2xy(double rbpn[3][3], double *x, double *y)
4/*
5** - - - - - - - - - -
6** e r a 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** Given:
13** rbpn double[3][3] celestial-to-true matrix (Note 1)
14**
15** Returned:
16** x,y double Celestial Intermediate Pole (Note 2)
17**
18** Notes:
19**
20** 1) The matrix rbpn transforms vectors from GCRS to true equator (and
21** CIO or equinox) of date, and therefore the Celestial Intermediate
22** Pole unit vector is the bottom row of the matrix.
23**
24** 2) The arguments x,y are components of the Celestial Intermediate
25** Pole unit vector in the Geocentric Celestial Reference System.
26**
27** Reference:
28**
29** "Expressions for the Celestial Intermediate Pole and Celestial
30** Ephemeris Origin consistent with the IAU 2000A precession-
31** nutation model", Astron.Astrophys. 400, 1145-1154
32** (2003)
33**
34** n.b. The celestial ephemeris origin (CEO) was renamed "celestial
35** intermediate origin" (CIO) by IAU 2006 Resolution 2.
36**
37** Copyright (C) 2013-2015, NumFOCUS Foundation.
38** Derived, with permission, from the SOFA library. See notes at end of file.
39*/
40{
41/* Extract the X,Y coordinates. */
42 *x = rbpn[2][0];
43 *y = rbpn[2][1];
44
45 return;
46
47}
48/*----------------------------------------------------------------------
49**
50**
51** Copyright (C) 2013-2015, NumFOCUS Foundation.
52** All rights reserved.
53**
54** This library is derived, with permission, from the International
55** Astronomical Union's "Standards of Fundamental Astronomy" library,
56** available from http://www.iausofa.org.
57**
58** The ERFA version is intended to retain identical functionality to
59** the SOFA library, but made distinct through different function and
60** file names, as set out in the SOFA license conditions. The SOFA
61** original has a role as a reference standard for the IAU and IERS,
62** and consequently redistribution is permitted only in its unaltered
63** state. The ERFA version is not subject to this restriction and
64** therefore can be included in distributions which do not support the
65** concept of "read only" software.
66**
67** Although the intent is to replicate the SOFA API (other than
68** replacement of prefix names) and results (with the exception of
69** bugs; any that are discovered will be fixed), SOFA is not
70** responsible for any errors found in this version of the library.
71**
72** If you wish to acknowledge the SOFA heritage, please acknowledge
73** that you are using a library derived from SOFA, rather than SOFA
74** itself.
75**
76**
77** TERMS AND CONDITIONS
78**
79** Redistribution and use in source and binary forms, with or without
80** modification, are permitted provided that the following conditions
81** are met:
82**
83** 1 Redistributions of source code must retain the above copyright
84** notice, this list of conditions and the following disclaimer.
85**
86** 2 Redistributions in binary form must reproduce the above copyright
87** notice, this list of conditions and the following disclaimer in
88** the documentation and/or other materials provided with the
89** distribution.
90**
91** 3 Neither the name of the Standards Of Fundamental Astronomy Board,
92** the International Astronomical Union nor the names of its
93** contributors may be used to endorse or promote products derived
94** from this software without specific prior written permission.
95**
96** THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
97** "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
98** LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
99** FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
100** COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
101** INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
102** BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
103** LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
104** CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
105** LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
106** ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
107** POSSIBILITY OF SUCH DAMAGE.
108**
109*/
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