File Coverage

erfasrc/src/s06a.c

Criterion	Covered	Total	%
statement	0	5	0.0
branch			n/a
condition			n/a
subroutine			n/a
pod			n/a
total	0	5	0.0

line	stmt	code
1		#include "erfa.h"
2
3	0	double eraS06a(double date1, double date2)
4		/*
5		** - - - - - - - -
6		** e r a S 0 6 a
7		** - - - - - - - -
8		**
9		** The CIO locator s, positioning the Celestial Intermediate Origin on
10		** the equator of the Celestial Intermediate Pole, using the IAU 2006
11		** precession and IAU 2000A nutation models.
12		**
13		** Given:
14		** date1,date2 double TT as a 2-part Julian Date (Note 1)
15		**
16		** Returned (function value):
17		** double the CIO locator s in radians (Note 2)
18		**
19		** Notes:
20		**
21		** 1) The TT date date1+date2 is a Julian Date, apportioned in any
22		** convenient way between the two arguments. For example,
23		** JD(TT)=2450123.7 could be expressed in any of these ways,
24		** among others:
25		**
26		** date1 date2
27		**
28		** 2450123.7 0.0 (JD method)
29		** 2451545.0 -1421.3 (J2000 method)
30		** 2400000.5 50123.2 (MJD method)
31		** 2450123.5 0.2 (date & time method)
32		**
33		** The JD method is the most natural and convenient to use in
34		** cases where the loss of several decimal digits of resolution
35		** is acceptable. The J2000 method is best matched to the way
36		** the argument is handled internally and will deliver the
37		** optimum resolution. The MJD method and the date & time methods
38		** are both good compromises between resolution and convenience.
39		**
40		** 2) The CIO locator s is the difference between the right ascensions
41		** of the same point in two systems. The two systems are the GCRS
42		** and the CIP,CIO, and the point is the ascending node of the
43		** CIP equator. The CIO locator s remains a small fraction of
44		** 1 arcsecond throughout 1900-2100.
45		**
46		** 3) The series used to compute s is in fact for s+XY/2, where X and Y
47		** are the x and y components of the CIP unit vector; this series is
48		** more compact than a direct series for s would be. The present
49		** function uses the full IAU 2000A nutation model when predicting
50		** the CIP position.
51		**
52		** Called:
53		** eraPnm06a classical NPB matrix, IAU 2006/2000A
54		** eraBpn2xy extract CIP X,Y coordinates from NPB matrix
55		** eraS06 the CIO locator s, given X,Y, IAU 2006
56		**
57		** References:
58		**
59		** Capitaine, N., Chapront, J., Lambert, S. and Wallace, P.,
60		** "Expressions for the Celestial Intermediate Pole and Celestial
61		** Ephemeris Origin consistent with the IAU 2000A precession-
62		** nutation model", Astron.Astrophys. 400, 1145-1154 (2003)
63		**
64		** n.b. The celestial ephemeris origin (CEO) was renamed "celestial
65		** intermediate origin" (CIO) by IAU 2006 Resolution 2.
66		**
67		** Capitaine, N. & Wallace, P.T., 2006, Astron.Astrophys. 450, 855
68		**
69		** McCarthy, D. D., Petit, G. (eds.), 2004, IERS Conventions (2003),
70		** IERS Technical Note No. 32, BKG
71		**
72		** Wallace, P.T. & Capitaine, N., 2006, Astron.Astrophys. 459, 981
73		**
74		** Copyright (C) 2013-2020, NumFOCUS Foundation.
75		** Derived, with permission, from the SOFA library. See notes at end of file.
76		*/
77		{
78		double rnpb[3][3], x, y, s;
79
80
81		/* Bias-precession-nutation-matrix, IAU 20006/2000A. */
82	0	eraPnm06a(date1, date2, rnpb);
83
84		/* Extract the CIP coordinates. */
85	0	eraBpn2xy(rnpb, &x, &y);
86
87		/* Compute the CIO locator s, given the CIP coordinates. */
88	0	s = eraS06(date1, date2, x, y);
89
90	0	return s;
91
92		}
93		/*----------------------------------------------------------------------
94		**
95		**
96		** Copyright (C) 2013-2020, NumFOCUS Foundation.
97		** All rights reserved.
98		**
99		** This library is derived, with permission, from the International
100		** Astronomical Union's "Standards of Fundamental Astronomy" library,
101		** available from http://www.iausofa.org.
102		**
103		** The ERFA version is intended to retain identical functionality to
104		** the SOFA library, but made distinct through different function and
105		** file names, as set out in the SOFA license conditions. The SOFA
106		** original has a role as a reference standard for the IAU and IERS,
107		** and consequently redistribution is permitted only in its unaltered
108		** state. The ERFA version is not subject to this restriction and
109		** therefore can be included in distributions which do not support the
110		** concept of "read only" software.
111		**
112		** Although the intent is to replicate the SOFA API (other than
113		** replacement of prefix names) and results (with the exception of
114		** bugs; any that are discovered will be fixed), SOFA is not
115		** responsible for any errors found in this version of the library.
116		**
117		** If you wish to acknowledge the SOFA heritage, please acknowledge
118		** that you are using a library derived from SOFA, rather than SOFA
119		** itself.
120		**
121		**
122		** TERMS AND CONDITIONS
123		**
124		** Redistribution and use in source and binary forms, with or without
125		** modification, are permitted provided that the following conditions
126		** are met:
127		**
128		** 1 Redistributions of source code must retain the above copyright
129		** notice, this list of conditions and the following disclaimer.
130		**
131		** 2 Redistributions in binary form must reproduce the above copyright
132		** notice, this list of conditions and the following disclaimer in
133		** the documentation and/or other materials provided with the
134		** distribution.
135		**
136		** 3 Neither the name of the Standards Of Fundamental Astronomy Board,
137		** the International Astronomical Union nor the names of its
138		** contributors may be used to endorse or promote products derived
139		** from this software without specific prior written permission.
140		**
141		** THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
142		** "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
143		** LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
144		** FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
145		** COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
146		** INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
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149		** CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
150		** LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
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152		** POSSIBILITY OF SUCH DAMAGE.
153		**
154		*/