source: branches/FACT++_lidctrl_usb/erfa/src/cal2jd.c@ 19875

Last change on this file since 19875 was 18711, checked in by tbretz, 10 years ago
Updated to ERFA 1.3.0 (no relevant code change except the leap second at the beginning of 2017)
File size: 5.4 KB
Line 
1#include "erfa.h"
2
3int eraCal2jd(int iy, int im, int id, double *djm0, double *djm)
4/*
5** - - - - - - - - - -
6** e r a C a l 2 j d
7** - - - - - - - - - -
8**
9** Gregorian Calendar to Julian Date.
10**
11** Given:
12** iy,im,id int year, month, day in Gregorian calendar (Note 1)
13**
14** Returned:
15** djm0 double MJD zero-point: always 2400000.5
16** djm double Modified Julian Date for 0 hrs
17**
18** Returned (function value):
19** int status:
20** 0 = OK
21** -1 = bad year (Note 3: JD not computed)
22** -2 = bad month (JD not computed)
23** -3 = bad day (JD computed)
24**
25** Notes:
26**
27** 1) The algorithm used is valid from -4800 March 1, but this
28** implementation rejects dates before -4799 January 1.
29**
30** 2) The Julian Date is returned in two pieces, in the usual ERFA
31** manner, which is designed to preserve time resolution. The
32** Julian Date is available as a single number by adding djm0 and
33** djm.
34**
35** 3) In early eras the conversion is from the "Proleptic Gregorian
36** Calendar"; no account is taken of the date(s) of adoption of
37** the Gregorian Calendar, nor is the AD/BC numbering convention
38** observed.
39**
40** Reference:
41**
42** Explanatory Supplement to the Astronomical Almanac,
43** P. Kenneth Seidelmann (ed), University Science Books (1992),
44** Section 12.92 (p604).
45**
46** Copyright (C) 2013-2016, NumFOCUS Foundation.
47** Derived, with permission, from the SOFA library. See notes at end of file.
48*/
49{
50 int j, ly, my;
51 long iypmy;
52
53/* Earliest year allowed (4800BC) */
54 const int IYMIN = -4799;
55
56/* Month lengths in days */
57 static const int mtab[]
58 = {31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31};
59
60
61/* Preset status. */
62 j = 0;
63
64/* Validate year and month. */
65 if (iy < IYMIN) return -1;
66 if (im < 1 || im > 12) return -2;
67
68/* If February in a leap year, 1, otherwise 0. */
69 ly = ((im == 2) && !(iy%4) && (iy%100 || !(iy%400)));
70
71/* Validate day, taking into account leap years. */
72 if ( (id < 1) || (id > (mtab[im-1] + ly))) j = -3;
73
74/* Return result. */
75 my = (im - 14) / 12;
76 iypmy = (long) (iy + my);
77 *djm0 = ERFA_DJM0;
78 *djm = (double)((1461L * (iypmy + 4800L)) / 4L
79 + (367L * (long) (im - 2 - 12 * my)) / 12L
80 - (3L * ((iypmy + 4900L) / 100L)) / 4L
81 + (long) id - 2432076L);
82
83/* Return status. */
84 return j;
85
86}
87/*----------------------------------------------------------------------
88**
89**
90** Copyright (C) 2013-2016, NumFOCUS Foundation.
91** All rights reserved.
92**
93** This library is derived, with permission, from the International
94** Astronomical Union's "Standards of Fundamental Astronomy" library,
95** available from http://www.iausofa.org.
96**
97** The ERFA version is intended to retain identical functionality to
98** the SOFA library, but made distinct through different function and
99** file names, as set out in the SOFA license conditions. The SOFA
100** original has a role as a reference standard for the IAU and IERS,
101** and consequently redistribution is permitted only in its unaltered
102** state. The ERFA version is not subject to this restriction and
103** therefore can be included in distributions which do not support the
104** concept of "read only" software.
105**
106** Although the intent is to replicate the SOFA API (other than
107** replacement of prefix names) and results (with the exception of
108** bugs; any that are discovered will be fixed), SOFA is not
109** responsible for any errors found in this version of the library.
110**
111** If you wish to acknowledge the SOFA heritage, please acknowledge
112** that you are using a library derived from SOFA, rather than SOFA
113** itself.
114**
115**
116** TERMS AND CONDITIONS
117**
118** Redistribution and use in source and binary forms, with or without
119** modification, are permitted provided that the following conditions
120** are met:
121**
122** 1 Redistributions of source code must retain the above copyright
123** notice, this list of conditions and the following disclaimer.
124**
125** 2 Redistributions in binary form must reproduce the above copyright
126** notice, this list of conditions and the following disclaimer in
127** the documentation and/or other materials provided with the
128** distribution.
129**
130** 3 Neither the name of the Standards Of Fundamental Astronomy Board,
131** the International Astronomical Union nor the names of its
132** contributors may be used to endorse or promote products derived
133** from this software without specific prior written permission.
134**
135** THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
136** "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
137** LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
138** FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
139** COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
140** INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
141** BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
142** LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
143** CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
144** LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
145** ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
146** POSSIBILITY OF SUCH DAMAGE.
147**
148*/
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