source: trunk/FACT++/erfa/src/pom00.c@ 20115

Last change on this file since 20115 was 18921, checked in by tbretz, 7 years ago
Updated to ERFA 1.4.0
File size: 4.9 KB
Line 
1#include "erfa.h"
2
3void eraPom00(double xp, double yp, double sp, double rpom[3][3])
4/*
5** - - - - - - - - - -
6** e r a P o m 0 0
7** - - - - - - - - - -
8**
9** Form the matrix of polar motion for a given date, IAU 2000.
10**
11** Given:
12** xp,yp double coordinates of the pole (radians, Note 1)
13** sp double the TIO locator s' (radians, Note 2)
14**
15** Returned:
16** rpom double[3][3] polar-motion matrix (Note 3)
17**
18** Notes:
19**
20** 1) The arguments xp and yp are the coordinates (in radians) of the
21** Celestial Intermediate Pole with respect to the International
22** Terrestrial Reference System (see IERS Conventions 2003),
23** measured along the meridians to 0 and 90 deg west respectively.
24**
25** 2) The argument sp is the TIO locator s', in radians, which
26** positions the Terrestrial Intermediate Origin on the equator. It
27** is obtained from polar motion observations by numerical
28** integration, and so is in essence unpredictable. However, it is
29** dominated by a secular drift of about 47 microarcseconds per
30** century, and so can be taken into account by using s' = -47*t,
31** where t is centuries since J2000.0. The function eraSp00
32** implements this approximation.
33**
34** 3) The matrix operates in the sense V(TRS) = rpom * V(CIP), meaning
35** that it is the final rotation when computing the pointing
36** direction to a celestial source.
37**
38** Called:
39** eraIr initialize r-matrix to identity
40** eraRz rotate around Z-axis
41** eraRy rotate around Y-axis
42** eraRx rotate around X-axis
43**
44** Reference:
45**
46** McCarthy, D. D., Petit, G. (eds.), IERS Conventions (2003),
47** IERS Technical Note No. 32, BKG (2004)
48**
49** Copyright (C) 2013-2017, NumFOCUS Foundation.
50** Derived, with permission, from the SOFA library. See notes at end of file.
51*/
52{
53
54/* Construct the matrix. */
55 eraIr(rpom);
56 eraRz(sp, rpom);
57 eraRy(-xp, rpom);
58 eraRx(-yp, rpom);
59
60 return;
61
62}
63/*----------------------------------------------------------------------
64**
65**
66** Copyright (C) 2013-2017, NumFOCUS Foundation.
67** All rights reserved.
68**
69** This library is derived, with permission, from the International
70** Astronomical Union's "Standards of Fundamental Astronomy" library,
71** available from http://www.iausofa.org.
72**
73** The ERFA version is intended to retain identical functionality to
74** the SOFA library, but made distinct through different function and
75** file names, as set out in the SOFA license conditions. The SOFA
76** original has a role as a reference standard for the IAU and IERS,
77** and consequently redistribution is permitted only in its unaltered
78** state. The ERFA version is not subject to this restriction and
79** therefore can be included in distributions which do not support the
80** concept of "read only" software.
81**
82** Although the intent is to replicate the SOFA API (other than
83** replacement of prefix names) and results (with the exception of
84** bugs; any that are discovered will be fixed), SOFA is not
85** responsible for any errors found in this version of the library.
86**
87** If you wish to acknowledge the SOFA heritage, please acknowledge
88** that you are using a library derived from SOFA, rather than SOFA
89** itself.
90**
91**
92** TERMS AND CONDITIONS
93**
94** Redistribution and use in source and binary forms, with or without
95** modification, are permitted provided that the following conditions
96** are met:
97**
98** 1 Redistributions of source code must retain the above copyright
99** notice, this list of conditions and the following disclaimer.
100**
101** 2 Redistributions in binary form must reproduce the above copyright
102** notice, this list of conditions and the following disclaimer in
103** the documentation and/or other materials provided with the
104** distribution.
105**
106** 3 Neither the name of the Standards Of Fundamental Astronomy Board,
107** the International Astronomical Union nor the names of its
108** contributors may be used to endorse or promote products derived
109** from this software without specific prior written permission.
110**
111** THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
112** "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
113** LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
114** FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
115** COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
116** INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
117** BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
118** LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
119** CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
120** LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
121** ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
122** POSSIBILITY OF SUCH DAMAGE.
123**
124*/
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