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/** * Persian Calendar see: http://code.google.com/p/persian-calendar/ Copyright (C) 2012 Mortezaadi@gmail.com PersianCalendarUtils.java/*w w w .ja v a2 s. c om*/ Persian Calendar 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/>. */ package ir.smartlab.persindatepicker.util; /** * algorithms for converting Julian days to the Persian calendar, and vice versa * are adopted from <a * href="casema.nl/couprie/calmath/persian/index.html">couprie.nl</a> written in * VB. The algorithms is not exactly the same as its original. I've done some * minor changes in the sake of performances and corrected some bugs. * * @author Morteza contact: <a * href="mailto:Mortezaadi@gmail.com">Mortezaadi@gmail.com</a> * @version 1.0 * */ public class PersianCalendarUtils { /** * Converts a provided Persian (Shamsi) date to the Julian Day Number (i.e. * the number of days since January 1 in the year 4713 BC). Since the * Persian calendar is a highly regular calendar, converting to and from a * Julian Day Number is not as difficult as it looks. Basically it's a * mather of dividing, rounding and multiplying. This routine uses Julian * Day Number 1948321 as focal point, since that Julian Day Number * corresponds with 1 Farvardin (1) 1. * * @param year * int persian year * @param month * int persian month * @param day * int persian day * @return long */ public static long persianToJulian(long year, int month, int day) { return 365L * ((ceil(year - 474L, 2820D) + 474L) - 1L) + ((long) Math.floor((682L * (ceil(year - 474L, 2820D) + 474L) - 110L) / 2816D)) + (PersianCalendarConstants.PERSIAN_EPOCH - 1L) + 1029983L * ((long) Math.floor((year - 474L) / 2820D)) + (month < 7 ? 31 * month : 30 * month + 6) + day; } /** * Calculate whether current year is Leap year in persian or not * * @return boolean */ public static boolean isPersianLeapYear(int persianYear) { return PersianCalendarUtils.ceil((38D + (PersianCalendarUtils.ceil(persianYear - 474L, 2820L) + 474L)) * 682D, 2816D) < 682L; } /** * Converts a provided Julian Day Number (i.e. the number of days since * January 1 in the year 4713 BC) to the Persian (Shamsi) date. Since the * Persian calendar is a highly regular calendar, converting to and from a * Julian Day Number is not as difficult as it looks. Basically it's a * mather of dividing, rounding and multiplying. * * @param julianDate * @return long */ public static long julianToPersian(long julianDate) { long persianEpochInJulian = julianDate - persianToJulian(475L, 0, 1); long cyear = ceil(persianEpochInJulian, 1029983D); long ycycle = cyear != 1029982L ? ((long) Math.floor((2816D * (double) cyear + 1031337D) / 1028522D)) : 2820L; long year = 474L + 2820L * ((long) Math.floor(persianEpochInJulian / 1029983D)) + ycycle; long aux = (1L + julianDate) - persianToJulian(year, 0, 1); int month = (int) (aux > 186L ? Math.ceil((double) (aux - 6L) / 30D) - 1 : Math.ceil((double) aux / 31D) - 1); int day = (int) (julianDate - (persianToJulian(year, month, 1) - 1L)); return (year << 16) | (month << 8) | day; } /** * Ceil function in original algorithm * * @param double1 * @param double2 * @return long */ public static long ceil(double double1, double double2) { return (long) (double1 - double2 * Math.floor(double1 / double2)); } }