
<!--

/*  You may notice that a variety of array variables logically local
    to functions are declared globally here.  In JavaScript, construction
    of an array variable from source code occurs as the code is
    interpreted.  Making these variables pseudo-globals permits us
    to avoid overhead constructing and disposing of them in each
    call on the function in which they are used.  */

var J0000 = 1721424.5;                // Julian date of Gregorian epoch: 0000-01-01
var J1970 = 2440587.5;                // Julian date at Unix epoch: 1970-01-01
var JMJD  = 2400000.5;                // Epoch of Modified Julian Date system
var J1900 = 2415020.5;                // Epoch (day 1) of Excel 1900 date system (PC)
var J1904 = 2416480.5;                // Epoch (day 0) of Excel 1904 date system (Mac)

var NormLeap = new Array("Normal year", "Leap year");

/*  WEEKDAY_BEFORE  --  Return Julian date of given weekday (0 = Sunday)
                        in the seven days ending on jd.  */

function weekday_before(weekday, jd)
{
    return jd - jwday(jd - weekday);
}

/*  SEARCH_WEEKDAY  --  Determine the Julian date for: 

            weekday      Day of week desired, 0 = Sunday
            jd           Julian date to begin search
            direction    1 = next weekday, -1 = last weekday
            offset       Offset from jd to begin search
*/

function search_weekday(weekday, jd, direction, offset)
{
    return weekday_before(weekday, jd + (direction * offset));
}

//  Utility weekday functions, just wrappers for search_weekday

function nearest_weekday(weekday, jd)
{
    return search_weekday(weekday, jd, 1, 3);
}

function next_weekday(weekday, jd)
{
    return search_weekday(weekday, jd, 1, 7);
}

function next_or_current_weekday(weekday, jd)
{
    return search_weekday(weekday, jd, 1, 6);
}

function previous_weekday(weekday, jd)
{
    return search_weekday(weekday, jd, -1, 1);
}

function previous_or_current_weekday(weekday, jd)
{
    return search_weekday(weekday, jd, 1, 0);
}

function TestSomething()
{
}

//  LEAP_GREGORIAN  --  Is a given year in the Gregorian calendar a leap year ?

function leap_gregorian(year)
{
    return ((year % 4) == 0) &&
            (!(((year % 100) == 0) && ((year % 400) != 0)));
}

//  GREGORIAN_TO_JD  --  Determine Julian day number from Gregorian calendar date

var GREGORIAN_EPOCH = 1721425.5;

function gregorian_to_jd(year, month, day)
{
    return (GREGORIAN_EPOCH - 1) +
           (365 * (year - 1)) +
           Math.floor((year - 1) / 4) +
           (-Math.floor((year - 1) / 100)) +
           Math.floor((year - 1) / 400) +
           Math.floor((((367 * month) - 362) / 12) +
           ((month <= 2) ? 0 :
                               (leap_gregorian(year) ? -1 : -2)
           ) +
           day);
}

//  JD_TO_GREGORIAN  --  Calculate Gregorian calendar date from Julian day

function jd_to_gregorian(jd) {
    var wjd, depoch, quadricent, dqc, cent, dcent, quad, dquad,
        yindex, dyindex, year, yearday, leapadj;

    wjd = Math.floor(jd - 0.5) + 0.5;
    depoch = wjd - GREGORIAN_EPOCH;
    quadricent = Math.floor(depoch / 146097);
    dqc = mod(depoch, 146097);
    cent = Math.floor(dqc / 36524);
    dcent = mod(dqc, 36524);
    quad = Math.floor(dcent / 1461);
    dquad = mod(dcent, 1461);
    yindex = Math.floor(dquad / 365);
    year = (quadricent * 400) + (cent * 100) + (quad * 4) + yindex;
    if (!((cent == 4) || (yindex == 4))) {
        year++;
    }
    yearday = wjd - gregorian_to_jd(year, 1, 1);
    leapadj = ((wjd < gregorian_to_jd(year, 3, 1)) ? 0
                                                  :
                  (leap_gregorian(year) ? 1 : 2)
              );
    month = Math.floor((((yearday + leapadj) * 12) + 373) / 367);
    day = (wjd - gregorian_to_jd(year, month, 1)) + 1;

    return new Array(year, month, day);
}

//  ISO_TO_JULIAN  --  Return Julian day of given ISO year, week, and day

function n_weeks(weekday, jd, nthweek)
{
    var j = 7 * nthweek;

    if (nthweek > 0) {
        j += previous_weekday(weekday, jd);
    } else {
        j += next_weekday(weekday, jd);
    }
    return j;
}

function iso_to_julian(year, week, day)
{
    return day + n_weeks(0, gregorian_to_jd(year - 1, 12, 28), week);
}

//  JD_TO_ISO  --  Return array of ISO (year, week, day) for Julian day

function jd_to_iso(jd)
{
    var year, week, day;

    year = jd_to_gregorian(jd - 3)[0];
    if (jd >= iso_to_julian(year + 1, 1, 1)) {
        year++;
    }
    week = Math.floor((jd - iso_to_julian(year, 1, 1)) / 7) + 1;
    day = jwday(jd);
    if (day == 0) {
        day = 7;
    }
    return new Array(year, week, day);
}

//  ISO_DAY_TO_JULIAN  --  Return Julian day of given ISO year, and day of year

function iso_day_to_julian(year, day)
{
    return (day - 1) + gregorian_to_jd(year, 1, 1);
}

//  JD_TO_ISO_DAY  --  Return array of ISO (year, day_of_year) for Julian day

function jd_to_iso_day(jd)
{
    var year, day;

    year = jd_to_gregorian(jd)[0];
    day = Math.floor(jd - gregorian_to_jd(year, 1, 1)) + 1;
    return new Array(year, day);
}

/*  PAD  --  Pad a string to a given length with a given fill character.  */

function pad(str, howlong, padwith) {
    var s = str.toString();

    while (s.length < howlong) {
        s = padwith + s;
    }
    return s;
}

//  LEAP_ISLAMIC  --  Is a given year a leap year in the Islamic calendar ?

function leap_islamic(year)
{
    return (((year * 11) + 14) % 30) < 11;
}

//  ISLAMIC_TO_JD  --  Determine Julian day from Islamic date

var ISLAMIC_EPOCH = 1948439.5;
var ISLAMIC_WEEKDAYS = new Array("al-'ahad", "al-'ithnayn",
                                 "ath-thalatha'", "al-'arb`a'",
                                 "al-khamis", "al-jum`a", "as-sabt");

function islamic_to_jd(year, month, day)
{
    return (day +
            Math.ceil(29.5 * (month - 1)) +
            (year - 1) * 354 +
            Math.floor((3 + (11 * year)) / 30) +
            ISLAMIC_EPOCH) - 1;
}

//  JD_TO_ISLAMIC  --  Calculate Islamic date from Julian day

function jd_to_islamic(jd)
{
    var year, month, day;

    jd = Math.floor(jd) + 0.5;
    year = Math.floor(((30 * (jd - ISLAMIC_EPOCH)) + 10646) / 10631);
    month = Math.min(12,
                Math.ceil((jd - (29 + islamic_to_jd(year, 1, 1))) / 29.5) + 1);
    day = (jd - islamic_to_jd(year, month, 1)) + 1;
    return new Array(year, month, day);
}

//  LEAP_PERSIAN  --  Is a given year a leap year in the Persian calendar ?

function leap_persian(year)
{
    return ((((((year - ((year > 0) ? 474 : 473)) % 2820) + 474) + 38) * 682) % 2816) < 682;
}

//  PERSIAN_TO_JD  --  Determine Julian day from Persian date

var PERSIAN_EPOCH = 1948320.5;
var PERSIAN_WEEKDAYS = new Array("Yekshanbeh", "Doshanbeh",
                                 "Seshhanbeh", "Chaharshanbeh",
                                 "Panjshanbeh", "Jomeh", "Shanbeh");

function persian_to_jd(year, month, day)
{
    var epbase, epyear;

    epbase = year - ((year >= 0) ? 474 : 473);
    epyear = 474 + mod(epbase, 2820);

    return day +
            ((month <= 7) ?
                ((month - 1) * 31) :
                (((month - 1) * 30) + 6)
            ) +
            Math.floor(((epyear * 682) - 110) / 2816) +
            (epyear - 1) * 365 +
            Math.floor(epbase / 2820) * 1029983 +
            (PERSIAN_EPOCH - 1);
}

//  JD_TO_PERSIAN  --  Calculate Persian date from Julian day

function jd_to_persian(jd)
{
    var year, month, day, depoch, cycle, cyear, ycycle,
        aux1, aux2, yday;


    jd = Math.floor(jd) + 0.5;

    depoch = jd - persian_to_jd(475, 1, 1);
    cycle = Math.floor(depoch / 1029983);
    cyear = mod(depoch, 1029983);
    if (cyear == 1029982) {
        ycycle = 2820;
    } else {
        aux1 = Math.floor(cyear / 366);
        aux2 = mod(cyear, 366);
        ycycle = Math.floor(((2134 * aux1) + (2816 * aux2) + 2815) / 1028522) +
                    aux1 + 1;
    }
    year = ycycle + (2820 * cycle) + 474;
    if (year <= 0) {
        year--;
    }
    yday = (jd - persian_to_jd(year, 1, 1)) + 1;
    month = (yday <= 186) ? Math.ceil(yday / 31) : Math.ceil((yday - 6) / 30);
    day = (jd - persian_to_jd(year, month, 1)) + 1;
    return new Array(year, month, day);
}

/*  updateFromGregorian  --  Update all calendars from Gregorian.
                             "Why not Julian date?" you ask.  Because
                             starting from Gregorian guarantees we're
                             already snapped to an integral second, so
                             we don't get roundoff errors in other
                             calendars.  */

function updateFromGregorian()
{
    var j,i, year, mon, mday, hour, min, sec,
        weekday, julcal, hebcal, islcal, hmindex, utime, isoweek,
        may_countcal, mayhaabcal, maytzolkincal, bahcal, frrcal,
        indcal, isoday, xgregcal;
    var year1,mon1,mday1,hour1,min1,sec1;



    var today = new Date();
    
    var y = today.getYear();
    if (y < 1000) {
        y += 1900;
    }
    year = y;
    mon = today.getMonth();
    mday = today.getDate();
    hour = min = sec = 0;
    hour = "00";
    min = "00";
    sec = "00";
    
    var lastday = new Date(today);
    lastday = lastday - 24*60*60*1000;
    lastday = new Date(lastday);
    
    var y1 = lastday.getYear();
    if (y1 < 1000) {
        y1 += 1900;
    }
    year1 = y1;
    mon1 = lastday.getMonth();
    mday1 = lastday.getDate();
    hour1 = min1 = sec1 = 0;
    hour1 = "00";
    min1 = "00";
    sec1 = "00";
    
    //  Update Julian day

    j = gregorian_to_jd(year, mon + 1, mday) +
           ((sec + 60 * (min + 60 * hour)) / 86400.0);
           
    i = gregorian_to_jd(year1, mon1 + 1, mday1) +
           ((sec1 + 60 * (min1 + 60 * hour1)) / 86400.0);
    //  Update day of week in Gregorian box

  //  weekday = jwday(j);
    //document.gregorian.wday.value = Weekdays[weekday];

    //  Update leap year status in Gregorian box

    //document.gregorian.leap.value = NormLeap[leap_gregorian(year) ? 1 : 0];

    //  Update Islamic Calendar
    islcal = jd_to_islamic(j);
    document.getElementById("ysl").innerHTML = "｜伊斯兰教历:"
    document.getElementById("ysl").innerHTML += islcal[0] + "年";
    document.getElementById("ysl").innerHTML += islcal[1] + "月";
    document.getElementById("ysl").innerHTML += islcal[2] + "日";
    //  Update Persian Calendar

    
    
}

//  calcGregorian  --  Perform calculation starting with a Gregorian date

function calcGregorian()
{
    updateFromGregorian();
}

//  calcJulian  --  Perform calculation starting with a Julian date

function calcJulian()
{
    var j, date, time;

    j = new Number(document.julianday.day.value);
    date = jd_to_gregorian(j);
    time = jhms(j);
    //document.gregorian.year.value = date[0];
    //document.gregorian.month.selectedIndex = date[1] - 1;
    //document.gregorian.day.value = date[2];
    //document.gregorian.hour.value = pad(time[0], 2, " ");
    //document.gregorian.min.value = pad(time[1], 2, "0");
    //document.gregorian.sec.value = pad(time[2], 2, "0");
    updateFromGregorian();
}

//  setJulian  --  Set Julian date and update all calendars

function setJulian(j)
{
    document.julianday.day.value = new Number(j);
    calcJulian();
}

//  calcJulianCalendar  --  Update from Julian calendar

function calcJulianCalendar()
{
    setJulian(julian_to_jd((new Number(document.juliancalendar.year.value)),
                           document.juliancalendar.month.selectedIndex + 1,
                           (new Number(document.juliancalendar.day.value))));
}

//  calcIslamic  --  Update from Islamic calendar

function calcIslamic()
{
    setJulian(islamic_to_jd((new Number(document.islamic.year.value)),
                           document.islamic.month.selectedIndex + 1,
                           (new Number(document.islamic.day.value))));
}

//  calcPersian  --  Update from Persian calendar

function calcPersian()
{
    setJulian(persian_to_jd((new Number(document.persian.year.value)),
                           document.persian.month.selectedIndex + 1,
                           (new Number(document.persian.day.value))));
}

//  calcGregSerial  --  Update from Gregorian serial day number

function calcGregSerial()
{
    setJulian((new Number(document.gregserial.day.value)) + J0000);
}

// -->