FACT++  1.0
taiut1.c
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1 #include "erfa.h"
2 
3 int eraTaiut1(double tai1, double tai2, double dta,
4  double *ut11, double *ut12)
5 /*
6 ** - - - - - - - - - -
7 ** e r a T a i u t 1
8 ** - - - - - - - - - -
9 **
10 ** Time scale transformation: International Atomic Time, TAI, to
11 ** Universal Time, UT1.
12 **
13 ** Given:
14 ** tai1,tai2 double TAI as a 2-part Julian Date
15 ** dta double UT1-TAI in seconds
16 **
17 ** Returned:
18 ** ut11,ut12 double UT1 as a 2-part Julian Date
19 **
20 ** Returned (function value):
21 ** int status: 0 = OK
22 **
23 ** Notes:
24 **
25 ** 1) tai1+tai2 is Julian Date, apportioned in any convenient way
26 ** between the two arguments, for example where tai1 is the Julian
27 ** Day Number and tai2 is the fraction of a day. The returned
28 ** UT11,UT12 follow suit.
29 **
30 ** 2) The argument dta, i.e. UT1-TAI, is an observed quantity, and is
31 ** available from IERS tabulations.
32 **
33 ** Reference:
34 **
35 ** Explanatory Supplement to the Astronomical Almanac,
36 ** P. Kenneth Seidelmann (ed), University Science Books (1992)
37 **
38 ** Copyright (C) 2013-2015, NumFOCUS Foundation.
39 ** Derived, with permission, from the SOFA library. See notes at end of file.
40 */
41 {
42  double dtad;
43 
44 /* Result, safeguarding precision. */
45  dtad = dta / ERFA_DAYSEC;
46  if ( tai1 > tai2 ) {
47  *ut11 = tai1;
48  *ut12 = tai2 + dtad;
49  } else {
50  *ut11 = tai1 + dtad;
51  *ut12 = tai2;
52  }
53 
54 /* Status (always OK). */
55  return 0;
56 
57 }
58 /*----------------------------------------------------------------------
59 **
60 **
61 ** Copyright (C) 2013-2015, NumFOCUS Foundation.
62 ** All rights reserved.
63 **
64 ** This library is derived, with permission, from the International
65 ** Astronomical Union's "Standards of Fundamental Astronomy" library,
66 ** available from http://www.iausofa.org.
67 **
68 ** The ERFA version is intended to retain identical functionality to
69 ** the SOFA library, but made distinct through different function and
70 ** file names, as set out in the SOFA license conditions. The SOFA
71 ** original has a role as a reference standard for the IAU and IERS,
72 ** and consequently redistribution is permitted only in its unaltered
73 ** state. The ERFA version is not subject to this restriction and
74 ** therefore can be included in distributions which do not support the
75 ** concept of "read only" software.
76 **
77 ** Although the intent is to replicate the SOFA API (other than
78 ** replacement of prefix names) and results (with the exception of
79 ** bugs; any that are discovered will be fixed), SOFA is not
80 ** responsible for any errors found in this version of the library.
81 **
82 ** If you wish to acknowledge the SOFA heritage, please acknowledge
83 ** that you are using a library derived from SOFA, rather than SOFA
84 ** itself.
85 **
86 **
87 ** TERMS AND CONDITIONS
88 **
89 ** Redistribution and use in source and binary forms, with or without
90 ** modification, are permitted provided that the following conditions
91 ** are met:
92 **
93 ** 1 Redistributions of source code must retain the above copyright
94 ** notice, this list of conditions and the following disclaimer.
95 **
96 ** 2 Redistributions in binary form must reproduce the above copyright
97 ** notice, this list of conditions and the following disclaimer in
98 ** the documentation and/or other materials provided with the
99 ** distribution.
100 **
101 ** 3 Neither the name of the Standards Of Fundamental Astronomy Board,
102 ** the International Astronomical Union nor the names of its
103 ** contributors may be used to endorse or promote products derived
104 ** from this software without specific prior written permission.
105 **
106 ** THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
107 ** "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
108 ** LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
109 ** FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
110 ** COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
111 ** INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
112 ** BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
113 ** LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
114 ** CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
115 ** LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
116 ** ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
117 ** POSSIBILITY OF SUCH DAMAGE.
118 **
119 */
ERFA_DAYSEC
#define ERFA_DAYSEC
Definition: erfam.h:75
eraTaiut1
int eraTaiut1(double tai1, double tai2, double dta, double *ut11, double *ut12)
Definition: taiut1.c:3