1 #include "erfa.h"
2
eraPnm80(double date1,double date2,double rmatpn[3][3])3 void eraPnm80(double date1, double date2, double rmatpn[3][3])
4 /*
5 ** - - - - - - - - -
6 ** e r a P n m 8 0
7 ** - - - - - - - - -
8 **
9 ** Form the matrix of precession/nutation for a given date, IAU 1976
10 ** precession model, IAU 1980 nutation model.
11 **
12 ** Given:
13 ** date1,date2 double TDB date (Note 1)
14 **
15 ** Returned:
16 ** rmatpn double[3][3] combined precession/nutation matrix
17 **
18 ** Notes:
19 **
20 ** 1) The TDB date date1+date2 is a Julian Date, apportioned in any
21 ** convenient way between the two arguments. For example,
22 ** JD(TDB)=2450123.7 could be expressed in any of these ways,
23 ** among others:
24 **
25 ** date1 date2
26 **
27 ** 2450123.7 0.0 (JD method)
28 ** 2451545.0 -1421.3 (J2000 method)
29 ** 2400000.5 50123.2 (MJD method)
30 ** 2450123.5 0.2 (date & time method)
31 **
32 ** The JD method is the most natural and convenient to use in
33 ** cases where the loss of several decimal digits of resolution
34 ** is acceptable. The J2000 method is best matched to the way
35 ** the argument is handled internally and will deliver the
36 ** optimum resolution. The MJD method and the date & time methods
37 ** are both good compromises between resolution and convenience.
38 **
39 ** 2) The matrix operates in the sense V(date) = rmatpn * V(J2000),
40 ** where the p-vector V(date) is with respect to the true equatorial
41 ** triad of date date1+date2 and the p-vector V(J2000) is with
42 ** respect to the mean equatorial triad of epoch J2000.0.
43 **
44 ** Called:
45 ** eraPmat76 precession matrix, IAU 1976
46 ** eraNutm80 nutation matrix, IAU 1980
47 ** eraRxr product of two r-matrices
48 **
49 ** Reference:
50 **
51 ** Explanatory Supplement to the Astronomical Almanac,
52 ** P. Kenneth Seidelmann (ed), University Science Books (1992),
53 ** Section 3.3 (p145).
54 **
55 ** Copyright (C) 2013-2014, NumFOCUS Foundation.
56 ** Derived, with permission, from the SOFA library. See notes at end of file.
57 */
58 {
59 double rmatp[3][3], rmatn[3][3];
60
61
62 /* Precession matrix, J2000.0 to date. */
63 eraPmat76(date1, date2, rmatp);
64
65 /* Nutation matrix. */
66 eraNutm80(date1, date2, rmatn);
67
68 /* Combine the matrices: PN = N x P. */
69 eraRxr(rmatn, rmatp, rmatpn);
70
71 return;
72
73 }
74 /*----------------------------------------------------------------------
75 **
76 **
77 ** Copyright (C) 2013-2014, NumFOCUS Foundation.
78 ** All rights reserved.
79 **
80 ** This library is derived, with permission, from the International
81 ** Astronomical Union's "Standards of Fundamental Astronomy" library,
82 ** available from http://www.iausofa.org.
83 **
84 ** The ERFA version is intended to retain identical functionality to
85 ** the SOFA library, but made distinct through different function and
86 ** file names, as set out in the SOFA license conditions. The SOFA
87 ** original has a role as a reference standard for the IAU and IERS,
88 ** and consequently redistribution is permitted only in its unaltered
89 ** state. The ERFA version is not subject to this restriction and
90 ** therefore can be included in distributions which do not support the
91 ** concept of "read only" software.
92 **
93 ** Although the intent is to replicate the SOFA API (other than
94 ** replacement of prefix names) and results (with the exception of
95 ** bugs; any that are discovered will be fixed), SOFA is not
96 ** responsible for any errors found in this version of the library.
97 **
98 ** If you wish to acknowledge the SOFA heritage, please acknowledge
99 ** that you are using a library derived from SOFA, rather than SOFA
100 ** itself.
101 **
102 **
103 ** TERMS AND CONDITIONS
104 **
105 ** Redistribution and use in source and binary forms, with or without
106 ** modification, are permitted provided that the following conditions
107 ** are met:
108 **
109 ** 1 Redistributions of source code must retain the above copyright
110 ** notice, this list of conditions and the following disclaimer.
111 **
112 ** 2 Redistributions in binary form must reproduce the above copyright
113 ** notice, this list of conditions and the following disclaimer in
114 ** the documentation and/or other materials provided with the
115 ** distribution.
116 **
117 ** 3 Neither the name of the Standards Of Fundamental Astronomy Board,
118 ** the International Astronomical Union nor the names of its
119 ** contributors may be used to endorse or promote products derived
120 ** from this software without specific prior written permission.
121 **
122 ** THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
123 ** "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
124 ** LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
125 ** FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
126 ** COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
127 ** INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
128 ** BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
129 ** LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
130 ** CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
131 ** LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
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133 ** POSSIBILITY OF SUCH DAMAGE.
134 **
135 */
136