File Coverage

erfasrc/src/pb06.c

Criterion	Covered	Total	%
statement	0	9	0.0
branch	0	2	0.0
condition			n/a
subroutine			n/a
pod			n/a
total	0	11	0.0

line	stmt	bran	code
1			#include "erfa.h"
2
3	0		void eraPb06(double date1, double date2,
4			double bzeta, double bz, double *btheta)
5			/*
6			** - - - - - - - -
7			** e r a P b 0 6
8			** - - - - - - - -
9			**
10			** This function forms three Euler angles which implement general
11			** precession from epoch J2000.0, using the IAU 2006 model. Frame
12			** bias (the offset between ICRS and mean J2000.0) is included.
13			**
14			** Given:
15			** date1,date2 double TT as a 2-part Julian Date (Note 1)
16			**
17			** Returned:
18			** bzeta double 1st rotation: radians cw around z
19			** bz double 3rd rotation: radians cw around z
20			** btheta double 2nd rotation: radians ccw around y
21			**
22			** Notes:
23			**
24			** 1) The TT date date1+date2 is a Julian Date, apportioned in any
25			** convenient way between the two arguments. For example,
26			** JD(TT)=2450123.7 could be expressed in any of these ways,
27			** among others:
28			**
29			** date1 date2
30			**
31			** 2450123.7 0.0 (JD method)
32			** 2451545.0 -1421.3 (J2000 method)
33			** 2400000.5 50123.2 (MJD method)
34			** 2450123.5 0.2 (date & time method)
35			**
36			** The JD method is the most natural and convenient to use in
37			** cases where the loss of several decimal digits of resolution
38			** is acceptable. The J2000 method is best matched to the way
39			** the argument is handled internally and will deliver the
40			** optimum resolution. The MJD method and the date & time methods
41			** are both good compromises between resolution and convenience.
42			**
43			** 2) The traditional accumulated precession angles zeta_A, z_A,
44			** theta_A cannot be obtained in the usual way, namely through
45			** polynomial expressions, because of the frame bias. The latter
46			** means that two of the angles undergo rapid changes near this
47			** date. They are instead the results of decomposing the
48			** precession-bias matrix obtained by using the Fukushima-Williams
49			** method, which does not suffer from the problem. The
50			** decomposition returns values which can be used in the
51			** conventional formulation and which include frame bias.
52			**
53			** 3) The three angles are returned in the conventional order, which
54			** is not the same as the order of the corresponding Euler
55			** rotations. The precession-bias matrix is
56			** R_3(-z) x R_2(+theta) x R_3(-zeta).
57			**
58			** 4) Should zeta_A, z_A, theta_A angles be required that do not
59			** contain frame bias, they are available by calling the ERFA
60			** function eraP06e.
61			**
62			** Called:
63			** eraPmat06 PB matrix, IAU 2006
64			** eraRz rotate around Z-axis
65			**
66			** Copyright (C) 2013-2019, NumFOCUS Foundation.
67			** Derived, with permission, from the SOFA library. See notes at end of file.
68			*/
69			{
70			double r[3][3], r31, r32;
71
72
73			/* Precession matrix via Fukushima-Williams angles. */
74	0		eraPmat06(date1, date2, r);
75
76			/* Solve for z. */
77	0		*bz = atan2(r[1][2], r[0][2]);
78
79			/* Remove it from the matrix. */
80	0		eraRz(*bz, r);
81
82			/* Solve for the remaining two angles. */
83	0		*bzeta = atan2 (r[1][0], r[1][1]);
84	0		r31 = r[2][0];
85	0		r32 = r[2][1];
86	0	0	btheta = atan2(-ERFA_DSIGN(sqrt(r31 r31 + r32 * r32), r[0][2]),
87			r[2][2]);
88
89	0		return;
90
91			}
92			/*----------------------------------------------------------------------
93			**
94			**
95			** Copyright (C) 2013-2019, NumFOCUS Foundation.
96			** All rights reserved.
97			**
98			** This library is derived, with permission, from the International
99			** Astronomical Union's "Standards of Fundamental Astronomy" library,
100			** available from http://www.iausofa.org.
101			**
102			** The ERFA version is intended to retain identical functionality to
103			** the SOFA library, but made distinct through different function and
104			** file names, as set out in the SOFA license conditions. The SOFA
105			** original has a role as a reference standard for the IAU and IERS,
106			** and consequently redistribution is permitted only in its unaltered
107			** state. The ERFA version is not subject to this restriction and
108			** therefore can be included in distributions which do not support the
109			** concept of "read only" software.
110			**
111			** Although the intent is to replicate the SOFA API (other than
112			** replacement of prefix names) and results (with the exception of
113			** bugs; any that are discovered will be fixed), SOFA is not
114			** responsible for any errors found in this version of the library.
115			**
116			** If you wish to acknowledge the SOFA heritage, please acknowledge
117			** that you are using a library derived from SOFA, rather than SOFA
118			** itself.
119			**
120			**
121			** TERMS AND CONDITIONS
122			**
123			** Redistribution and use in source and binary forms, with or without
124			** modification, are permitted provided that the following conditions
125			** are met:
126			**
127			** 1 Redistributions of source code must retain the above copyright
128			** notice, this list of conditions and the following disclaimer.
129			**
130			** 2 Redistributions in binary form must reproduce the above copyright
131			** notice, this list of conditions and the following disclaimer in
132			** the documentation and/or other materials provided with the
133			** distribution.
134			**
135			** 3 Neither the name of the Standards Of Fundamental Astronomy Board,
136			** the International Astronomical Union nor the names of its
137			** contributors may be used to endorse or promote products derived
138			** from this software without specific prior written permission.
139			**
140			** THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
141			** "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
142			** LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
143			** FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
144			** COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
145			** INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
146			** BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
147			** LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
148			** CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
149			** LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
150			** ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
151			** POSSIBILITY OF SUCH DAMAGE.
152			**
153			*/