1 #include "erfa.h"
2
eraNumat(double epsa,double dpsi,double deps,double rmatn[3][3])3 void eraNumat(double epsa, double dpsi, double deps, double rmatn[3][3])
4 /*
5 ** - - - - - - - - -
6 ** e r a N u m a t
7 ** - - - - - - - - -
8 **
9 ** Form the matrix of nutation.
10 **
11 ** Given:
12 ** epsa double mean obliquity of date (Note 1)
13 ** dpsi,deps double nutation (Note 2)
14 **
15 ** Returned:
16 ** rmatn double[3][3] nutation matrix (Note 3)
17 **
18 ** Notes:
19 **
20 **
21 ** 1) The supplied mean obliquity epsa, must be consistent with the
22 ** precession-nutation models from which dpsi and deps were obtained.
23 **
24 ** 2) The caller is responsible for providing the nutation components;
25 ** they are in longitude and obliquity, in radians and are with
26 ** respect to the equinox and ecliptic of date.
27 **
28 ** 3) The matrix operates in the sense V(true) = rmatn * V(mean),
29 ** where the p-vector V(true) is with respect to the true
30 ** equatorial triad of date and the p-vector V(mean) is with
31 ** respect to the mean equatorial triad of date.
32 **
33 ** Called:
34 ** eraIr initialize r-matrix to identity
35 ** eraRx rotate around X-axis
36 ** eraRz rotate around Z-axis
37 **
38 ** Reference:
39 **
40 ** Explanatory Supplement to the Astronomical Almanac,
41 ** P. Kenneth Seidelmann (ed), University Science Books (1992),
42 ** Section 3.222-3 (p114).
43 **
44 ** Copyright (C) 2013-2020, NumFOCUS Foundation.
45 ** Derived, with permission, from the SOFA library. See notes at end of file.
46 */
47 {
48 /* Build the rotation matrix. */
49 eraIr(rmatn);
50 eraRx(epsa, rmatn);
51 eraRz(-dpsi, rmatn);
52 eraRx(-(epsa + deps), rmatn);
53
54 return;
55
56 }
57 /*----------------------------------------------------------------------
58 **
59 **
60 ** Copyright (C) 2013-2020, NumFOCUS Foundation.
61 ** All rights reserved.
62 **
63 ** This library is derived, with permission, from the International
64 ** Astronomical Union's "Standards of Fundamental Astronomy" library,
65 ** available from http://www.iausofa.org.
66 **
67 ** The ERFA version is intended to retain identical functionality to
68 ** the SOFA library, but made distinct through different function and
69 ** file names, as set out in the SOFA license conditions. The SOFA
70 ** original has a role as a reference standard for the IAU and IERS,
71 ** and consequently redistribution is permitted only in its unaltered
72 ** state. The ERFA version is not subject to this restriction and
73 ** therefore can be included in distributions which do not support the
74 ** concept of "read only" software.
75 **
76 ** Although the intent is to replicate the SOFA API (other than
77 ** replacement of prefix names) and results (with the exception of
78 ** bugs; any that are discovered will be fixed), SOFA is not
79 ** responsible for any errors found in this version of the library.
80 **
81 ** If you wish to acknowledge the SOFA heritage, please acknowledge
82 ** that you are using a library derived from SOFA, rather than SOFA
83 ** itself.
84 **
85 **
86 ** TERMS AND CONDITIONS
87 **
88 ** Redistribution and use in source and binary forms, with or without
89 ** modification, are permitted provided that the following conditions
90 ** are met:
91 **
92 ** 1 Redistributions of source code must retain the above copyright
93 ** notice, this list of conditions and the following disclaimer.
94 **
95 ** 2 Redistributions in binary form must reproduce the above copyright
96 ** notice, this list of conditions and the following disclaimer in
97 ** the documentation and/or other materials provided with the
98 ** distribution.
99 **
100 ** 3 Neither the name of the Standards Of Fundamental Astronomy Board,
101 ** the International Astronomical Union nor the names of its
102 ** contributors may be used to endorse or promote products derived
103 ** from this software without specific prior written permission.
104 **
105 ** THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
106 ** "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
107 ** LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
108 ** FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
109 ** COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
110 ** INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
111 ** BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
112 ** LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
113 ** CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
114 ** LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
115 ** ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
116 ** POSSIBILITY OF SUCH DAMAGE.
117 **
118 */
119