File Coverage

erfasrc/src/gst06a.c

Criterion	Covered	Total	%
statement	4	4	100.0
branch			n/a
condition			n/a
subroutine			n/a
pod			n/a
total	4	4	100.0

line	stmt	code
1		#include "erfa.h"
2
3	3	double eraGst06a(double uta, double utb, double tta, double ttb)
4		/*
5		** - - - - - - - - - -
6		** e r a G s t 0 6 a
7		** - - - - - - - - - -
8		**
9		** Greenwich apparent sidereal time (consistent with IAU 2000 and 2006
10		** resolutions).
11		**
12		** Given:
13		** uta,utb double UT1 as a 2-part Julian Date (Notes 1,2)
14		** tta,ttb double TT as a 2-part Julian Date (Notes 1,2)
15		**
16		** Returned (function value):
17		** double Greenwich apparent sidereal time (radians)
18		**
19		** Notes:
20		**
21		** 1) The UT1 and TT dates uta+utb and tta+ttb respectively, are both
22		** Julian Dates, apportioned in any convenient way between the
23		** argument pairs. For example, JD=2450123.7 could be expressed in
24		** any of these ways, among others:
25		**
26		** Part A Part B
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 (in the case of UT; the TT is not at all critical
36		** in this respect). The J2000 and MJD methods are good compromises
37		** between resolution and convenience. For UT, the date & time
38		** method is best matched to the algorithm that is used by the Earth
39		** rotation angle function, called internally: maximum precision is
40		** delivered when the uta argument is for 0hrs UT1 on the day in
41		** question and the utb argument lies in the range 0 to 1, or vice
42		** versa.
43		**
44		** 2) Both UT1 and TT are required, UT1 to predict the Earth rotation
45		** and TT to predict the effects of precession-nutation. If UT1 is
46		** used for both purposes, errors of order 100 microarcseconds
47		** result.
48		**
49		** 3) This GAST is compatible with the IAU 2000/2006 resolutions and
50		** must be used only in conjunction with IAU 2006 precession and
51		** IAU 2000A nutation.
52		**
53		** 4) The result is returned in the range 0 to 2pi.
54		**
55		** Called:
56		** eraPnm06a classical NPB matrix, IAU 2006/2000A
57		** eraGst06 Greenwich apparent ST, IAU 2006, given NPB matrix
58		**
59		** Reference:
60		**
61		** Wallace, P.T. & Capitaine, N., 2006, Astron.Astrophys. 459, 981
62		**
63		** Copyright (C) 2013-2019, NumFOCUS Foundation.
64		** Derived, with permission, from the SOFA library. See notes at end of file.
65		*/
66		{
67		double rnpb[3][3], gst;
68
69
70		/* Classical nutation x precession x bias matrix, IAU 2000A. */
71	3	eraPnm06a(tta, ttb, rnpb);
72
73		/* Greenwich apparent sidereal time. */
74	3	gst = eraGst06(uta, utb, tta, ttb, rnpb);
75
76	3	return gst;
77
78		}
79		/*----------------------------------------------------------------------
80		**
81		**
82		** Copyright (C) 2013-2019, NumFOCUS Foundation.
83		** All rights reserved.
84		**
85		** This library is derived, with permission, from the International
86		** Astronomical Union's "Standards of Fundamental Astronomy" library,
87		** available from http://www.iausofa.org.
88		**
89		** The ERFA version is intended to retain identical functionality to
90		** the SOFA library, but made distinct through different function and
91		** file names, as set out in the SOFA license conditions. The SOFA
92		** original has a role as a reference standard for the IAU and IERS,
93		** and consequently redistribution is permitted only in its unaltered
94		** state. The ERFA version is not subject to this restriction and
95		** therefore can be included in distributions which do not support the
96		** concept of "read only" software.
97		**
98		** Although the intent is to replicate the SOFA API (other than
99		** replacement of prefix names) and results (with the exception of
100		** bugs; any that are discovered will be fixed), SOFA is not
101		** responsible for any errors found in this version of the library.
102		**
103		** If you wish to acknowledge the SOFA heritage, please acknowledge
104		** that you are using a library derived from SOFA, rather than SOFA
105		** itself.
106		**
107		**
108		** TERMS AND CONDITIONS
109		**
110		** Redistribution and use in source and binary forms, with or without
111		** modification, are permitted provided that the following conditions
112		** are met:
113		**
114		** 1 Redistributions of source code must retain the above copyright
115		** notice, this list of conditions and the following disclaimer.
116		**
117		** 2 Redistributions in binary form must reproduce the above copyright
118		** notice, this list of conditions and the following disclaimer in
119		** the documentation and/or other materials provided with the
120		** distribution.
121		**
122		** 3 Neither the name of the Standards Of Fundamental Astronomy Board,
123		** the International Astronomical Union nor the names of its
124		** contributors may be used to endorse or promote products derived
125		** from this software without specific prior written permission.
126		**
127		** THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
128		** "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
129		** LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
130		** FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
131		** COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
132		** INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
133		** BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
134		** LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
135		** CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
136		** LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
137		** ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
138		** POSSIBILITY OF SUCH DAMAGE.
139		**
140		*/