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author | William Joye <wjoye@cfa.harvard.edu> | 2016-10-17 15:22:52 (GMT) |
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committer | William Joye <wjoye@cfa.harvard.edu> | 2016-10-17 15:22:52 (GMT) |
commit | 7dd9b970cec6832b8f6118dc2dd91a08d2836648 (patch) | |
tree | 4b3c86596ab87f35a3c6213397da07afe1e24d3e /ast/erfa/cal2jd.c | |
parent | d7bf7c61e8507e3cf51f195392c0f41f27ae18d8 (diff) | |
parent | 7fde2daeed593684120d75de07598154f3ddaf2c (diff) | |
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Merge commit '7fde2daeed593684120d75de07598154f3ddaf2c' as 'ast'
Diffstat (limited to 'ast/erfa/cal2jd.c')
-rw-r--r-- | ast/erfa/cal2jd.c | 148 |
1 files changed, 148 insertions, 0 deletions
diff --git a/ast/erfa/cal2jd.c b/ast/erfa/cal2jd.c new file mode 100644 index 0000000..e0a3439 --- /dev/null +++ b/ast/erfa/cal2jd.c @@ -0,0 +1,148 @@ +#include "erfa.h" + +int eraCal2jd(int iy, int im, int id, double *djm0, double *djm) +/* +** - - - - - - - - - - +** e r a C a l 2 j d +** - - - - - - - - - - +** +** Gregorian Calendar to Julian Date. +** +** Given: +** iy,im,id int year, month, day in Gregorian calendar (Note 1) +** +** Returned: +** djm0 double MJD zero-point: always 2400000.5 +** djm double Modified Julian Date for 0 hrs +** +** Returned (function value): +** int status: +** 0 = OK +** -1 = bad year (Note 3: JD not computed) +** -2 = bad month (JD not computed) +** -3 = bad day (JD computed) +** +** Notes: +** +** 1) The algorithm used is valid from -4800 March 1, but this +** implementation rejects dates before -4799 January 1. +** +** 2) The Julian Date is returned in two pieces, in the usual ERFA +** manner, which is designed to preserve time resolution. The +** Julian Date is available as a single number by adding djm0 and +** djm. +** +** 3) In early eras the conversion is from the "Proleptic Gregorian +** Calendar"; no account is taken of the date(s) of adoption of +** the Gregorian Calendar, nor is the AD/BC numbering convention +** observed. +** +** Reference: +** +** Explanatory Supplement to the Astronomical Almanac, +** P. Kenneth Seidelmann (ed), University Science Books (1992), +** Section 12.92 (p604). +** +** Copyright (C) 2013-2014, NumFOCUS Foundation. +** Derived, with permission, from the SOFA library. See notes at end of file. +*/ +{ + int j, ly, my; + long iypmy; + +/* Earliest year allowed (4800BC) */ + const int IYMIN = -4799; + +/* Month lengths in days */ + static const int mtab[] + = {31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31}; + + +/* Preset status. */ + j = 0; + +/* Validate year and month. */ + if (iy < IYMIN) return -1; + if (im < 1 || im > 12) return -2; + +/* If February in a leap year, 1, otherwise 0. */ + ly = ((im == 2) && !(iy%4) && (iy%100 || !(iy%400))); + +/* Validate day, taking into account leap years. */ + if ( (id < 1) || (id > (mtab[im-1] + ly))) j = -3; + +/* Return result. */ + my = (im - 14) / 12; + iypmy = (long) (iy + my); + *djm0 = ERFA_DJM0; + *djm = (double)((1461L * (iypmy + 4800L)) / 4L + + (367L * (long) (im - 2 - 12 * my)) / 12L + - (3L * ((iypmy + 4900L) / 100L)) / 4L + + (long) id - 2432076L); + +/* Return status. */ + return j; + +} +/*---------------------------------------------------------------------- +** +** +** Copyright (C) 2013-2014, NumFOCUS Foundation. +** All rights reserved. +** +** This library is derived, with permission, from the International +** Astronomical Union's "Standards of Fundamental Astronomy" library, +** available from http://www.iausofa.org. +** +** The ERFA version is intended to retain identical functionality to +** the SOFA library, but made distinct through different function and +** file names, as set out in the SOFA license conditions. The SOFA +** original has a role as a reference standard for the IAU and IERS, +** and consequently redistribution is permitted only in its unaltered +** state. The ERFA version is not subject to this restriction and +** therefore can be included in distributions which do not support the +** concept of "read only" software. +** +** Although the intent is to replicate the SOFA API (other than +** replacement of prefix names) and results (with the exception of +** bugs; any that are discovered will be fixed), SOFA is not +** responsible for any errors found in this version of the library. +** +** If you wish to acknowledge the SOFA heritage, please acknowledge +** that you are using a library derived from SOFA, rather than SOFA +** itself. +** +** +** TERMS AND CONDITIONS +** +** Redistribution and use in source and binary forms, with or without +** modification, are permitted provided that the following conditions +** are met: +** +** 1 Redistributions of source code must retain the above copyright +** notice, this list of conditions and the following disclaimer. +** +** 2 Redistributions in binary form must reproduce the above copyright +** notice, this list of conditions and the following disclaimer in +** the documentation and/or other materials provided with the +** distribution. +** +** 3 Neither the name of the Standards Of Fundamental Astronomy Board, +** the International Astronomical Union nor the names of its +** contributors may be used to endorse or promote products derived +** from this software without specific prior written permission. +** +** THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS +** "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT +** LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS +** FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE +** COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, +** INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, +** BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; +** LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER +** CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT +** LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN +** ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE +** POSSIBILITY OF SUCH DAMAGE. +** +*/ |