File Coverage

erfasrc/src/s00a.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 bran cond sub pod time code
1             #include "erfa.h"
2              
3 0           double eraS00a(double date1, double date2)
4             /*
5             ** - - - - - - - -
6             ** e r a S 0 0 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 2000A
11             ** precession-nutation model.
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
48             ** is 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. Faster results, with no significant loss of
51             ** accuracy, can be obtained via the function eraS00b, which uses
52             ** instead the IAU 2000B truncated model.
53             **
54             ** Called:
55             ** eraPnm00a classical NPB matrix, IAU 2000A
56             ** eraBnp2xy extract CIP X,Y from the BPN matrix
57             ** eraS00 the CIO locator s, given X,Y, IAU 2000A
58             **
59             ** References:
60             **
61             ** Capitaine, N., Chapront, J., Lambert, S. and Wallace, P.,
62             ** "Expressions for the Celestial Intermediate Pole and Celestial
63             ** Ephemeris Origin consistent with the IAU 2000A precession-
64             ** nutation model", Astron.Astrophys. 400, 1145-1154 (2003)
65             **
66             ** n.b. The celestial ephemeris origin (CEO) was renamed "celestial
67             ** intermediate origin" (CIO) by IAU 2006 Resolution 2.
68             **
69             ** McCarthy, D. D., Petit, G. (eds.), IERS Conventions (2003),
70             ** IERS Technical Note No. 32, BKG (2004)
71             **
72             ** Copyright (C) 2013-2019, NumFOCUS Foundation.
73             ** Derived, with permission, from the SOFA library. See notes at end of file.
74             */
75             {
76             double rbpn[3][3], x, y, s;
77              
78              
79             /* Bias-precession-nutation-matrix, IAU 2000A. */
80 0           eraPnm00a(date1, date2, rbpn);
81              
82             /* Extract the CIP coordinates. */
83 0           eraBpn2xy(rbpn, &x, &y);
84              
85             /* Compute the CIO locator s, given the CIP coordinates. */
86 0           s = eraS00(date1, date2, x, y);
87              
88 0           return s;
89              
90             }
91             /*----------------------------------------------------------------------
92             **
93             **
94             ** Copyright (C) 2013-2019, NumFOCUS Foundation.
95             ** All rights reserved.
96             **
97             ** This library is derived, with permission, from the International
98             ** Astronomical Union's "Standards of Fundamental Astronomy" library,
99             ** available from http://www.iausofa.org.
100             **
101             ** The ERFA version is intended to retain identical functionality to
102             ** the SOFA library, but made distinct through different function and
103             ** file names, as set out in the SOFA license conditions. The SOFA
104             ** original has a role as a reference standard for the IAU and IERS,
105             ** and consequently redistribution is permitted only in its unaltered
106             ** state. The ERFA version is not subject to this restriction and
107             ** therefore can be included in distributions which do not support the
108             ** concept of "read only" software.
109             **
110             ** Although the intent is to replicate the SOFA API (other than
111             ** replacement of prefix names) and results (with the exception of
112             ** bugs; any that are discovered will be fixed), SOFA is not
113             ** responsible for any errors found in this version of the library.
114             **
115             ** If you wish to acknowledge the SOFA heritage, please acknowledge
116             ** that you are using a library derived from SOFA, rather than SOFA
117             ** itself.
118             **
119             **
120             ** TERMS AND CONDITIONS
121             **
122             ** Redistribution and use in source and binary forms, with or without
123             ** modification, are permitted provided that the following conditions
124             ** are met:
125             **
126             ** 1 Redistributions of source code must retain the above copyright
127             ** notice, this list of conditions and the following disclaimer.
128             **
129             ** 2 Redistributions in binary form must reproduce the above copyright
130             ** notice, this list of conditions and the following disclaimer in
131             ** the documentation and/or other materials provided with the
132             ** distribution.
133             **
134             ** 3 Neither the name of the Standards Of Fundamental Astronomy Board,
135             ** the International Astronomical Union nor the names of its
136             ** contributors may be used to endorse or promote products derived
137             ** from this software without specific prior written permission.
138             **
139             ** THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
140             ** "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
141             ** LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
142             ** FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
143             ** COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
144             ** INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
145             ** BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
146             ** LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
147             ** CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
148             ** LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
149             ** ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
150             ** POSSIBILITY OF SUCH DAMAGE.
151             **
152             */