File Coverage

erfasrc/src/era00.c

Criterion	Covered	Total	%
statement	7	7	100.0
branch	1	2	50.0
condition			n/a
subroutine			n/a
pod			n/a
total	8	9	88.8

line	stmt	bran	code
1			#include "erfa.h"
2
3	19		double eraEra00(double dj1, double dj2)
4			/*
5			** - - - - - - - - -
6			** e r a E r a 0 0
7			** - - - - - - - - -
8			**
9			** Earth rotation angle (IAU 2000 model).
10			**
11			** Given:
12			** dj1,dj2 double UT1 as a 2-part Julian Date (see note)
13			**
14			** Returned (function value):
15			** double Earth rotation angle (radians), range 0-2pi
16			**
17			** Notes:
18			**
19			** 1) The UT1 date dj1+dj2 is a Julian Date, apportioned in any
20			** convenient way between the arguments dj1 and dj2. For example,
21			** JD(UT1)=2450123.7 could be expressed in any of these ways,
22			** among others:
23			**
24			** dj1 dj2
25			**
26			** 2450123.7 0.0 (JD method)
27			** 2451545.0 -1421.3 (J2000 method)
28			** 2400000.5 50123.2 (MJD method)
29			** 2450123.5 0.2 (date & time method)
30			**
31			** The JD method is the most natural and convenient to use in
32			** cases where the loss of several decimal digits of resolution
33			** is acceptable. The J2000 and MJD methods are good compromises
34			** between resolution and convenience. The date & time method is
35			** best matched to the algorithm used: maximum precision is
36			** delivered when the dj1 argument is for 0hrs UT1 on the day in
37			** question and the dj2 argument lies in the range 0 to 1, or vice
38			** versa.
39			**
40			** 2) The algorithm is adapted from Expression 22 of Capitaine et al.
41			** 2000. The time argument has been expressed in days directly,
42			** and, to retain precision, integer contributions have been
43			** eliminated. The same formulation is given in IERS Conventions
44			** (2003), Chap. 5, Eq. 14.
45			**
46			** Called:
47			** eraAnp normalize angle into range 0 to 2pi
48			**
49			** References:
50			**
51			** Capitaine N., Guinot B. and McCarthy D.D, 2000, Astron.
52			** Astrophys., 355, 398-405.
53			**
54			** McCarthy, D. D., Petit, G. (eds.), IERS Conventions (2003),
55			** IERS Technical Note No. 32, BKG (2004)
56			**
57			** Copyright (C) 2013-2020, NumFOCUS Foundation.
58			** Derived, with permission, from the SOFA library. See notes at end of file.
59			*/
60			{
61			double d1, d2, t, f, theta;
62
63
64			/* Days since fundamental epoch. */
65	19	50	if (dj1 < dj2) {
66			d1 = dj1;
67			d2 = dj2;
68			} else {
69			d1 = dj2;
70			d2 = dj1;
71			}
72	19		t = d1 + (d2- ERFA_DJ00);
73
74			/* Fractional part of T (days). */
75	19		f = fmod(d1, 1.0) + fmod(d2, 1.0);
76
77			/* Earth rotation angle at this UT1. */
78	19		theta = eraAnp(ERFA_D2PI * (f + 0.7790572732640
79	19		+ 0.00273781191135448 * t));
80
81	19		return theta;
82
83			}
84			/*----------------------------------------------------------------------
85			**
86			**
87			** Copyright (C) 2013-2020, NumFOCUS Foundation.
88			** All rights reserved.
89			**
90			** This library is derived, with permission, from the International
91			** Astronomical Union's "Standards of Fundamental Astronomy" library,
92			** available from http://www.iausofa.org.
93			**
94			** The ERFA version is intended to retain identical functionality to
95			** the SOFA library, but made distinct through different function and
96			** file names, as set out in the SOFA license conditions. The SOFA
97			** original has a role as a reference standard for the IAU and IERS,
98			** and consequently redistribution is permitted only in its unaltered
99			** state. The ERFA version is not subject to this restriction and
100			** therefore can be included in distributions which do not support the
101			** concept of "read only" software.
102			**
103			** Although the intent is to replicate the SOFA API (other than
104			** replacement of prefix names) and results (with the exception of
105			** bugs; any that are discovered will be fixed), SOFA is not
106			** responsible for any errors found in this version of the library.
107			**
108			** If you wish to acknowledge the SOFA heritage, please acknowledge
109			** that you are using a library derived from SOFA, rather than SOFA
110			** itself.
111			**
112			**
113			** TERMS AND CONDITIONS
114			**
115			** Redistribution and use in source and binary forms, with or without
116			** modification, are permitted provided that the following conditions
117			** are met:
118			**
119			** 1 Redistributions of source code must retain the above copyright
120			** notice, this list of conditions and the following disclaimer.
121			**
122			** 2 Redistributions in binary form must reproduce the above copyright
123			** notice, this list of conditions and the following disclaimer in
124			** the documentation and/or other materials provided with the
125			** distribution.
126			**
127			** 3 Neither the name of the Standards Of Fundamental Astronomy Board,
128			** the International Astronomical Union nor the names of its
129			** contributors may be used to endorse or promote products derived
130			** from this software without specific prior written permission.
131			**
132			** THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
133			** "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
134			** LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
135			** FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
136			** COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
137			** INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
138			** BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
139			** LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
140			** CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
141			** LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
142			** ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
143			** POSSIBILITY OF SUCH DAMAGE.
144			**
145			*/