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/*
* julian_date.h - Constants & declarations for julian date conversions
* Copyright (C) 2010 Shiva Iyer <shiva.iyer AT g m a i l DOT c o m>
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#ifndef _JULIAN_DATE_H_
#define _JULIAN_DATE_H_
/*
* This structure is used wherever a Julian Day Number (JDN) is expected or
* returned. Two doubles are used to preserve precision.
*
* A given JDN may be partitioned between date1 & date2 in any convenient
* manner. The JDN that corresponds to this structure is date1 + date2.
*/
struct julian_date {
double date1;
double date2;
};
#define J2000_EPOCH 2451545.0
#define MJD_EPOCH 2400000.5
#define JULIAN_CENTURY_LENGTH 36525.0
#define JULIAN_MILLENNIUM_LENGTH 365250.0
#define JULIAN_CENTURIES(d1, d2) \
(((d1 - J2000_EPOCH) + d2) / JULIAN_CENTURY_LENGTH)
#define JULIAN_MILLENNIA(d1, d2) \
(((d1 - J2000_EPOCH) + d2) / JULIAN_MILLENNIUM_LENGTH)
int calendar_to_julian_date(int year, int month, int day,struct julian_date *jd);
int julian_to_calendar_date(struct julian_date *jd, int *year, int *month,
int *day, double *day_fraction);
#endif
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