FACT++  1.0
pfw06.c
Go to the documentation of this file.
1 #include "erfa.h"
2 
3 void eraPfw06(double date1, double date2,
4  double *gamb, double *phib, double *psib, double *epsa)
5 /*
6 ** - - - - - - - - -
7 ** e r a P f w 0 6
8 ** - - - - - - - - -
9 **
10 ** Precession angles, IAU 2006 (Fukushima-Williams 4-angle formulation).
11 **
12 ** Given:
13 ** date1,date2 double TT as a 2-part Julian Date (Note 1)
14 **
15 ** Returned:
16 ** gamb double F-W angle gamma_bar (radians)
17 ** phib double F-W angle phi_bar (radians)
18 ** psib double F-W angle psi_bar (radians)
19 ** epsa double F-W angle epsilon_A (radians)
20 **
21 ** Notes:
22 **
23 ** 1) The TT date date1+date2 is a Julian Date, apportioned in any
24 ** convenient way between the two arguments. For example,
25 ** JD(TT)=2450123.7 could be expressed in any of these ways,
26 ** among others:
27 **
28 ** date1 date2
29 **
30 ** 2450123.7 0.0 (JD method)
31 ** 2451545.0 -1421.3 (J2000 method)
32 ** 2400000.5 50123.2 (MJD method)
33 ** 2450123.5 0.2 (date & time method)
34 **
35 ** The JD method is the most natural and convenient to use in
36 ** cases where the loss of several decimal digits of resolution
37 ** is acceptable. The J2000 method is best matched to the way
38 ** the argument is handled internally and will deliver the
39 ** optimum resolution. The MJD method and the date & time methods
40 ** are both good compromises between resolution and convenience.
41 **
42 ** 2) Naming the following points:
43 **
44 ** e = J2000.0 ecliptic pole,
45 ** p = GCRS pole,
46 ** E = mean ecliptic pole of date,
47 ** and P = mean pole of date,
48 **
49 ** the four Fukushima-Williams angles are as follows:
50 **
51 ** gamb = gamma_bar = epE
52 ** phib = phi_bar = pE
53 ** psib = psi_bar = pEP
54 ** epsa = epsilon_A = EP
55 **
56 ** 3) The matrix representing the combined effects of frame bias and
57 ** precession is:
58 **
59 ** PxB = R_1(-epsa).R_3(-psib).R_1(phib).R_3(gamb)
60 **
61 ** 4) The matrix representing the combined effects of frame bias,
62 ** precession and nutation is simply:
63 **
64 ** NxPxB = R_1(-epsa-dE).R_3(-psib-dP).R_1(phib).R_3(gamb)
65 **
66 ** where dP and dE are the nutation components with respect to the
67 ** ecliptic of date.
68 **
69 ** Reference:
70 **
71 ** Hilton, J. et al., 2006, Celest.Mech.Dyn.Astron. 94, 351
72 **
73 ** Called:
74 ** eraObl06 mean obliquity, IAU 2006
75 **
76 ** Copyright (C) 2013-2015, NumFOCUS Foundation.
77 ** Derived, with permission, from the SOFA library. See notes at end of file.
78 */
79 {
80  double t;
81 
82 /* Interval between fundamental date J2000.0 and given date (JC). */
83  t = ((date1 - ERFA_DJ00) + date2) / ERFA_DJC;
84 
85 /* P03 bias+precession angles. */
86  *gamb = ( -0.052928 +
87  ( 10.556378 +
88  ( 0.4932044 +
89  ( -0.00031238 +
90  ( -0.000002788 +
91  ( 0.0000000260 )
92  * t) * t) * t) * t) * t) * ERFA_DAS2R;
93  *phib = ( 84381.412819 +
94  ( -46.811016 +
95  ( 0.0511268 +
96  ( 0.00053289 +
97  ( -0.000000440 +
98  ( -0.0000000176 )
99  * t) * t) * t) * t) * t) * ERFA_DAS2R;
100  *psib = ( -0.041775 +
101  ( 5038.481484 +
102  ( 1.5584175 +
103  ( -0.00018522 +
104  ( -0.000026452 +
105  ( -0.0000000148 )
106  * t) * t) * t) * t) * t) * ERFA_DAS2R;
107  *epsa = eraObl06(date1, date2);
108 
109  return;
110 
111 }
112 /*----------------------------------------------------------------------
113 **
114 **
115 ** Copyright (C) 2013-2015, NumFOCUS Foundation.
116 ** All rights reserved.
117 **
118 ** This library is derived, with permission, from the International
119 ** Astronomical Union's "Standards of Fundamental Astronomy" library,
120 ** available from http://www.iausofa.org.
121 **
122 ** The ERFA version is intended to retain identical functionality to
123 ** the SOFA library, but made distinct through different function and
124 ** file names, as set out in the SOFA license conditions. The SOFA
125 ** original has a role as a reference standard for the IAU and IERS,
126 ** and consequently redistribution is permitted only in its unaltered
127 ** state. The ERFA version is not subject to this restriction and
128 ** therefore can be included in distributions which do not support the
129 ** concept of "read only" software.
130 **
131 ** Although the intent is to replicate the SOFA API (other than
132 ** replacement of prefix names) and results (with the exception of
133 ** bugs; any that are discovered will be fixed), SOFA is not
134 ** responsible for any errors found in this version of the library.
135 **
136 ** If you wish to acknowledge the SOFA heritage, please acknowledge
137 ** that you are using a library derived from SOFA, rather than SOFA
138 ** itself.
139 **
140 **
141 ** TERMS AND CONDITIONS
142 **
143 ** Redistribution and use in source and binary forms, with or without
144 ** modification, are permitted provided that the following conditions
145 ** are met:
146 **
147 ** 1 Redistributions of source code must retain the above copyright
148 ** notice, this list of conditions and the following disclaimer.
149 **
150 ** 2 Redistributions in binary form must reproduce the above copyright
151 ** notice, this list of conditions and the following disclaimer in
152 ** the documentation and/or other materials provided with the
153 ** distribution.
154 **
155 ** 3 Neither the name of the Standards Of Fundamental Astronomy Board,
156 ** the International Astronomical Union nor the names of its
157 ** contributors may be used to endorse or promote products derived
158 ** from this software without specific prior written permission.
159 **
160 ** THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
161 ** "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
162 ** LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
163 ** FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
164 ** COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
165 ** INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
166 ** BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
167 ** LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
168 ** CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
169 ** LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
170 ** ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
171 ** POSSIBILITY OF SUCH DAMAGE.
172 **
173 */
ERFA_DJ00
#define ERFA_DJ00
Definition: erfam.h:87
ERFA_DAS2R
#define ERFA_DAS2R
Definition: erfam.h:60
eraPfw06
void eraPfw06(double date1, double date2, double *gamb, double *phib, double *psib, double *epsa)
Definition: pfw06.c:3
eraObl06
double eraObl06(double date1, double date2)
Definition: obl06.c:3
ERFA_DJC
#define ERFA_DJC
Definition: erfam.h:81
t
TT t
Definition: test_client.c:26