1 #include "erfa.h"
2
eraC2tcio(double rc2i[3][3],double era,double rpom[3][3],double rc2t[3][3])3 void eraC2tcio(double rc2i[3][3], double era, double rpom[3][3],
4 double rc2t[3][3])
5 /*
6 ** - - - - - - - - - -
7 ** e r a C 2 t c i o
8 ** - - - - - - - - - -
9 **
10 ** Assemble the celestial to terrestrial matrix from CIO-based
11 ** components (the celestial-to-intermediate matrix, the Earth Rotation
12 ** Angle and the polar motion matrix).
13 **
14 ** Given:
15 ** rc2i double[3][3] celestial-to-intermediate matrix
16 ** era double Earth rotation angle (radians)
17 ** rpom double[3][3] polar-motion matrix
18 **
19 ** Returned:
20 ** rc2t double[3][3] celestial-to-terrestrial matrix
21 **
22 ** Notes:
23 **
24 ** 1) This function constructs the rotation matrix that transforms
25 ** vectors in the celestial system into vectors in the terrestrial
26 ** system. It does so starting from precomputed components, namely
27 ** the matrix which rotates from celestial coordinates to the
28 ** intermediate frame, the Earth rotation angle and the polar motion
29 ** matrix. One use of the present function is when generating a
30 ** series of celestial-to-terrestrial matrices where only the Earth
31 ** Rotation Angle changes, avoiding the considerable overhead of
32 ** recomputing the precession-nutation more often than necessary to
33 ** achieve given accuracy objectives.
34 **
35 ** 2) The relationship between the arguments is as follows:
36 **
37 ** [TRS] = RPOM * R_3(ERA) * rc2i * [CRS]
38 **
39 ** = rc2t * [CRS]
40 **
41 ** where [CRS] is a vector in the Geocentric Celestial Reference
42 ** System and [TRS] is a vector in the International Terrestrial
43 ** Reference System (see IERS Conventions 2003).
44 **
45 ** Called:
46 ** eraCr copy r-matrix
47 ** eraRz rotate around Z-axis
48 ** eraRxr product of two r-matrices
49 **
50 ** Reference:
51 **
52 ** McCarthy, D. D., Petit, G. (eds.), 2004, IERS Conventions (2003),
53 ** IERS Technical Note No. 32, BKG
54 **
55 ** This revision: 2021 May 11
56 **
57 ** Copyright (C) 2013-2021, NumFOCUS Foundation.
58 ** Derived, with permission, from the SOFA library. See notes at end of file.
59 */
60 {
61 double r[3][3];
62
63
64 /* Construct the matrix. */
65 eraCr(rc2i, r);
66 eraRz(era, r);
67 eraRxr(rpom, r, rc2t);
68
69 /* Finished. */
70
71 }
72 /*----------------------------------------------------------------------
73 **
74 **
75 ** Copyright (C) 2013-2021, NumFOCUS Foundation.
76 ** All rights reserved.
77 **
78 ** This library is derived, with permission, from the International
79 ** Astronomical Union's "Standards of Fundamental Astronomy" library,
80 ** available from http://www.iausofa.org.
81 **
82 ** The ERFA version is intended to retain identical functionality to
83 ** the SOFA library, but made distinct through different function and
84 ** file names, as set out in the SOFA license conditions. The SOFA
85 ** original has a role as a reference standard for the IAU and IERS,
86 ** and consequently redistribution is permitted only in its unaltered
87 ** state. The ERFA version is not subject to this restriction and
88 ** therefore can be included in distributions which do not support the
89 ** concept of "read only" software.
90 **
91 ** Although the intent is to replicate the SOFA API (other than
92 ** replacement of prefix names) and results (with the exception of
93 ** bugs; any that are discovered will be fixed), SOFA is not
94 ** responsible for any errors found in this version of the library.
95 **
96 ** If you wish to acknowledge the SOFA heritage, please acknowledge
97 ** that you are using a library derived from SOFA, rather than SOFA
98 ** itself.
99 **
100 **
101 ** TERMS AND CONDITIONS
102 **
103 ** Redistribution and use in source and binary forms, with or without
104 ** modification, are permitted provided that the following conditions
105 ** are met:
106 **
107 ** 1 Redistributions of source code must retain the above copyright
108 ** notice, this list of conditions and the following disclaimer.
109 **
110 ** 2 Redistributions in binary form must reproduce the above copyright
111 ** notice, this list of conditions and the following disclaimer in
112 ** the documentation and/or other materials provided with the
113 ** distribution.
114 **
115 ** 3 Neither the name of the Standards Of Fundamental Astronomy Board,
116 ** the International Astronomical Union nor the names of its
117 ** contributors may be used to endorse or promote products derived
118 ** from this software without specific prior written permission.
119 **
120 ** THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
121 ** "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
122 ** LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
123 ** FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
124 ** COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
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126 ** BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
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132 **
133 */
134