source: trunk/FACT++/erfa/src/ut1tt.c@ 18679

Last change on this file since 18679 was 18348, checked in by tbretz, 9 years ago
File size: 4.2 KB
Line 
1#include "erfa.h"
2
3int eraUt1tt(double ut11, double ut12, double dt,
4 double *tt1, double *tt2)
5/*
6** - - - - - - - - -
7** e r a U t 1 t t
8** - - - - - - - - -
9**
10** Time scale transformation: Universal Time, UT1, to Terrestrial
11** Time, TT.
12**
13** Given:
14** ut11,ut12 double UT1 as a 2-part Julian Date
15** dt double TT-UT1 in seconds
16**
17** Returned:
18** tt1,tt2 double TT as a 2-part Julian Date
19**
20** Returned (function value):
21** int status: 0 = OK
22**
23** Notes:
24**
25** 1) ut11+ut12 is Julian Date, apportioned in any convenient way
26** between the two arguments, for example where ut11 is the Julian
27** Day Number and ut12 is the fraction of a day. The returned
28** tt1,tt2 follow suit.
29**
30** 2) The argument dt is classical Delta T.
31**
32** Reference:
33**
34** Explanatory Supplement to the Astronomical Almanac,
35** P. Kenneth Seidelmann (ed), University Science Books (1992)
36**
37** Copyright (C) 2013-2015, NumFOCUS Foundation.
38** Derived, with permission, from the SOFA library. See notes at end of file.
39*/
40{
41 double dtd;
42
43/* Result, safeguarding precision. */
44 dtd = dt / ERFA_DAYSEC;
45 if ( ut11 > ut12 ) {
46 *tt1 = ut11;
47 *tt2 = ut12 + dtd;
48 } else {
49 *tt1 = ut11 + dtd;
50 *tt2 = ut12;
51 }
52
53/* Status (always OK). */
54 return 0;
55
56}
57/*----------------------------------------------------------------------
58**
59**
60** Copyright (C) 2013-2015, NumFOCUS Foundation.
61** All rights reserved.
62**
63** This library is derived, with permission, from the International
64** Astronomical Union's "Standards of Fundamental Astronomy" library,
65** available from http://www.iausofa.org.
66**
67** The ERFA version is intended to retain identical functionality to
68** the SOFA library, but made distinct through different function and
69** file names, as set out in the SOFA license conditions. The SOFA
70** original has a role as a reference standard for the IAU and IERS,
71** and consequently redistribution is permitted only in its unaltered
72** state. The ERFA version is not subject to this restriction and
73** therefore can be included in distributions which do not support the
74** concept of "read only" software.
75**
76** Although the intent is to replicate the SOFA API (other than
77** replacement of prefix names) and results (with the exception of
78** bugs; any that are discovered will be fixed), SOFA is not
79** responsible for any errors found in this version of the library.
80**
81** If you wish to acknowledge the SOFA heritage, please acknowledge
82** that you are using a library derived from SOFA, rather than SOFA
83** itself.
84**
85**
86** TERMS AND CONDITIONS
87**
88** Redistribution and use in source and binary forms, with or without
89** modification, are permitted provided that the following conditions
90** are met:
91**
92** 1 Redistributions of source code must retain the above copyright
93** notice, this list of conditions and the following disclaimer.
94**
95** 2 Redistributions in binary form must reproduce the above copyright
96** notice, this list of conditions and the following disclaimer in
97** the documentation and/or other materials provided with the
98** distribution.
99**
100** 3 Neither the name of the Standards Of Fundamental Astronomy Board,
101** the International Astronomical Union nor the names of its
102** contributors may be used to endorse or promote products derived
103** from this software without specific prior written permission.
104**
105** THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
106** "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
107** LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
108** FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
109** COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
110** INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
111** BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
112** LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
113** CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
114** LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
115** ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
116** POSSIBILITY OF SUCH DAMAGE.
117**
118*/
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