3 /* Discard the fractional part of a number, e.g., INT(3.2) = 3 */
8 /* Compute the (integral) Julian day number of day dd/mm/yyyy, i.e., the number
9 * of days between 1/1/4713 BC (Julian calendar) and dd/mm/yyyy.
10 * Formula from http://www.tondering.dk/claus/calendar.html
12 function jdFromDate(dd, mm, yy) {
14 a = INT((14 - mm) / 12);
17 jd = dd + INT((153*m+2)/5) + 365*y + INT(y/4) - INT(y/100) + INT(y/400) - 32045;
19 jd = dd + INT((153*m+2)/5) + 365*y + INT(y/4) - 32083;
24 /* Convert a Julian day number to day/month/year. Parameter jd is an integer */
25 function jdToDate(jd) {
26 var a, b, c, d, e, m, day, month, year;
27 if (jd > 2299160) { // After 5/10/1582, Gregorian calendar
29 b = INT((4*a+3)/146097);
30 c = a - INT((b*146097)/4);
35 d = INT((4*c+3)/1461);
36 e = c - INT((1461*d)/4);
38 day = e - INT((153*m+2)/5) + 1;
39 month = m + 3 - 12*INT(m/10);
40 year = b*100 + d - 4800 + INT(m/10);
41 return new Array(day, month, year);
44 /* Compute the time of the k-th new moon after the new moon of 1/1/1900 13:52 UCT
45 * (measured as the number of days since 1/1/4713 BC noon UCT, e.g., 2451545.125 is 1/1/2000 15:00 UTC).
46 * Returns a floating number, e.g., 2415079.9758617813 for k=2 or 2414961.935157746 for k=-2
47 * Algorithm from: "Astronomical Algorithms" by Jean Meeus, 1998
50 var T, T2, T3, dr, Jd1, M, Mpr, F, C1, deltat, JdNew;
51 T = k/1236.85; // Time in Julian centuries from 1900 January 0.5
55 Jd1 = 2415020.75933 + 29.53058868*k + 0.0001178*T2 - 0.000000155*T3;
56 Jd1 = Jd1 + 0.00033*Math.sin((166.56 + 132.87*T - 0.009173*T2)*dr); // Mean new moon
57 M = 359.2242 + 29.10535608*k - 0.0000333*T2 - 0.00000347*T3; // Sun's mean anomaly
58 Mpr = 306.0253 + 385.81691806*k + 0.0107306*T2 + 0.00001236*T3; // Moon's mean anomaly
59 F = 21.2964 + 390.67050646*k - 0.0016528*T2 - 0.00000239*T3; // Moon's argument of latitude
60 C1=(0.1734 - 0.000393*T)*Math.sin(M*dr) + 0.0021*Math.sin(2*dr*M);
61 C1 = C1 - 0.4068*Math.sin(Mpr*dr) + 0.0161*Math.sin(dr*2*Mpr);
62 C1 = C1 - 0.0004*Math.sin(dr*3*Mpr);
63 C1 = C1 + 0.0104*Math.sin(dr*2*F) - 0.0051*Math.sin(dr*(M+Mpr));
64 C1 = C1 - 0.0074*Math.sin(dr*(M-Mpr)) + 0.0004*Math.sin(dr*(2*F+M));
65 C1 = C1 - 0.0004*Math.sin(dr*(2*F-M)) - 0.0006*Math.sin(dr*(2*F+Mpr));
66 C1 = C1 + 0.0010*Math.sin(dr*(2*F-Mpr)) + 0.0005*Math.sin(dr*(2*Mpr+M));
68 deltat= 0.001 + 0.000839*T + 0.0002261*T2 - 0.00000845*T3 - 0.000000081*T*T3;
70 deltat= -0.000278 + 0.000265*T + 0.000262*T2;
72 JdNew = Jd1 + C1 - deltat;
76 /* Compute the longitude of the sun at any time.
77 * Parameter: floating number jdn, the number of days since 1/1/4713 BC noon
78 * Algorithm from: "Astronomical Algorithms" by Jean Meeus, 1998
80 function SunLongitude(jdn) {
81 var T, T2, dr, M, L0, DL, L;
82 T = (jdn - 2451545.0 ) / 36525; // Time in Julian centuries from 2000-01-01 12:00:00 GMT
84 dr = PI/180; // degree to radian
85 M = 357.52910 + 35999.05030*T - 0.0001559*T2 - 0.00000048*T*T2; // mean anomaly, degree
86 L0 = 280.46645 + 36000.76983*T + 0.0003032*T2; // mean longitude, degree
87 DL = (1.914600 - 0.004817*T - 0.000014*T2)*Math.sin(dr*M);
88 DL = DL + (0.019993 - 0.000101*T)*Math.sin(dr*2*M) + 0.000290*Math.sin(dr*3*M);
89 L = L0 + DL; // true longitude, degree
91 L = L - PI*2*(INT(L/(PI*2))); // Normalize to (0, 2*PI)
95 /* Compute sun position at midnight of the day with the given Julian day number.
96 * The time zone if the time difference between local time and UTC: 7.0 for UTC+7:00.
97 * The function returns a number between 0 and 11.
98 * From the day after March equinox and the 1st major term after March equinox, 0 is returned.
99 * After that, return 1, 2, 3 ...
101 function getSunLongitude(dayNumber, timeZone) {
102 return INT(SunLongitude(dayNumber - 0.5 - timeZone/24)/PI*6);
105 /* Compute the day of the k-th new moon in the given time zone.
106 * The time zone if the time difference between local time and UTC: 7.0 for UTC+7:00
108 function getNewMoonDay(k, timeZone) {
109 return INT(NewMoon(k) + 0.5 + timeZone/24);
112 /* Find the day that starts the luner month 11 of the given year for the given time zone */
113 function getLunarMonth11(yy, timeZone) {
114 var k, off, nm, sunLong;
115 //off = jdFromDate(31, 12, yy) - 2415021.076998695;
116 off = jdFromDate(31, 12, yy) - 2415021;
117 k = INT(off / 29.530588853);
118 nm = getNewMoonDay(k, timeZone);
119 sunLong = getSunLongitude(nm, timeZone); // sun longitude at local midnight
121 nm = getNewMoonDay(k-1, timeZone);
126 /* Find the index of the leap month after the month starting on the day a11. */
127 function getLeapMonthOffset(a11, timeZone) {
129 k = INT((a11 - 2415021.076998695) / 29.530588853 + 0.5);
131 i = 1; // We start with the month following lunar month 11
132 arc = getSunLongitude(getNewMoonDay(k+i, timeZone), timeZone);
136 arc = getSunLongitude(getNewMoonDay(k+i, timeZone), timeZone);
137 } while (arc != last && i < 14);
141 /* Comvert solar date dd/mm/yyyy to the corresponding lunar date */
142 function convertSolar2Lunar(dd, mm, yy, timeZone) {
143 var k, dayNumber, monthStart, a11, b11, lunarDay, lunarMonth, lunarYear, lunarLeap;
144 dayNumber = jdFromDate(dd, mm, yy);
145 k = INT((dayNumber - 2415021.076998695) / 29.530588853);
146 monthStart = getNewMoonDay(k+1, timeZone);
147 if (monthStart > dayNumber) {
148 monthStart = getNewMoonDay(k, timeZone);
150 //alert(dayNumber+" -> "+monthStart);
151 a11 = getLunarMonth11(yy, timeZone);
153 if (a11 >= monthStart) {
155 a11 = getLunarMonth11(yy-1, timeZone);
158 b11 = getLunarMonth11(yy+1, timeZone);
160 lunarDay = dayNumber-monthStart+1;
161 var diff = INT((monthStart - a11)/29);
163 lunarMonth = diff+11;
164 if (b11 - a11 > 365) {
165 var leapMonthDiff = getLeapMonthOffset(a11, timeZone);
166 if (diff >= leapMonthDiff) {
167 lunarMonth = diff + 10;
168 if (diff == leapMonthDiff) {
173 if (lunarMonth > 12) {
174 lunarMonth = lunarMonth - 12;
176 if (lunarMonth >= 11 && diff < 4) {
179 return new Array(lunarDay, lunarMonth, lunarYear, lunarLeap);
182 /* Convert a lunar date to the corresponding solar date */
183 function convertLunar2Solar(lunarDay, lunarMonth, lunarYear, lunarLeap, timeZone) {
184 var k, a11, b11, off, leapOff, leapMonth, monthStart;
185 if (lunarMonth < 11) {
186 a11 = getLunarMonth11(lunarYear-1, timeZone);
187 b11 = getLunarMonth11(lunarYear, timeZone);
189 a11 = getLunarMonth11(lunarYear, timeZone);
190 b11 = getLunarMonth11(lunarYear+1, timeZone);
192 k = INT(0.5 + (a11 - 2415021.076998695) / 29.530588853);
193 off = lunarMonth - 11;
197 if (b11 - a11 > 365) {
198 leapOff = getLeapMonthOffset(a11, timeZone);
199 leapMonth = leapOff - 2;
203 if (lunarLeap != 0 && lunarMonth != leapMonth) {
204 return new Array(0, 0, 0);
205 } else if (lunarLeap != 0 || off >= leapOff) {
209 monthStart = getNewMoonDay(k+off, timeZone);
210 return jdToDate(monthStart+lunarDay-1);