1 #include "erfa.h"
2 
eraCal2jd(int iy,int im,int id,double * djm0,double * djm)3 int 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) 2013-2014, 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) 2013-2014, 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 */
149