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Calendar.pmod
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YMD.pike
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pike.git/lib/modules/Calendar.pmod/YMD.pike:38:
protected string f_week_day_shortname_from_number; protected string f_week_day_name_from_number; protected string f_year_name_from_number; protected string f_year_number_from_name; protected int(0..1) year_leap_year(int y); protected int compat_week_day(int n);
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// Polynomial terms for calculating the difference between TDT and UTC.
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//
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// The polynomials have been taken from NASA:
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// @url{http://eclipse.gsfc.nasa.gov/SEhelp/deltatpoly2004.html@}
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//
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// Each entry is an @expr{array(float)@}:
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// @array
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// @elem float 0
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// End year for the range.
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// @elem float 1
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// Year offset.
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// @elem float 2
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// Year divisor.
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// @elem float 3..
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// Polynomial factors with the highest exponent first.
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// @endarray
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protected constant deltat_polynomials = ({
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({ -500.0, -1820.0, 100.0,
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-20.0, 0.0, 32.0, }),
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({ 500.0, 0.0, 100.0,
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0.0090316521, 0.022174192, -0.1798452,
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-5.952053, 33.78311, -1014.41, 10583.6, }),
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({ 1600.0, -1000.0, 100.0,
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0.0083572073, -0.005050998, -0.8503463,
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0.319781, 71.23472, -556.01, 1574.2, }),
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({ 1700.0, -1600.0, 1.0,
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0.000140272128, -0.01532, -0.9808, 120.0, }),
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({ 1800.0, -1700.0, 1.0,
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0.000000851788756, 0.00013336, -0.0059285, 0.1603, 8.83, }),
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({ 1860.0, -1800.0, 1.0,
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0.000000000875, -0.0000001699, 0.0000121272, -0.00037436,
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0.0041116, 0.0068612, -0.332447, 13.72, }),
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({ 1900.0, -1860.0, 1.0,
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0.000004288643, -0.0004473624, 0.01680668, -0.251754, 0.5737, 7.62, }),
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({ 1920.0, -1900.0, 1.0,
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-0.000197, 0.0061966, -0.0598939, 1.494119, -2.79, }),
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({ 1941.0, -1920.0, 1.0,
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0.0020936, -0.076100, 0.84493, 21.20, }),
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({ 1961.0, -1950.0, 1.0,
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0.0003926188, 0.0042918455, 0.407, 29.07, }),
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({ 1986.0, -1975.0, 1.0,
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0.001392758, 0.0038461538, 1.067, 45.45, }),
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({ 2005.0, -2000.0, 1.0,
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0.00002373599, 0.000651814, 0.0017275, -0.060374, 0.3345, 63.86, }),
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({ 2050.0, -2000.0, 1.0,
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0.005589, 0.32217, 62.92 }),
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({ 2150.0, -1820.0, 100.0,
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32.0-185.724, 56.28, -20.0, }),
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({ Math.inf, -1820.0, 100.0,
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32.0, 0.0, -20.0, }),
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});
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//! method float deltat(int unadjusted_utc)
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//! Terrestrial Dynamical Time difference from standard time.
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//!
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//! returns
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//! An approximation of the difference between TDT and UTC
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//! in fractional seconds at the specified time.
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//!
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//! The zero point is 1901-06-25T14:23:01 UTC
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//! (unix time -2162281019), ie the accumulated number
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//! of leap seconds since then is returned.
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//!
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//! note
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//! The function is based on polynomials provided by NASA,
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//! and the result may differ from actual for dates after 2004.
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float deltat(int unadjusted_utc)
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{
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// Approximation of the year. This ought to be good enough for
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// most purposes given the uncertainty in the table values.
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// 31556952 == 365.2425 * 24 * 60 * 60.
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float y = 1970.0 + unadjusted_utc/31556952.0;
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array(float) polynomial;
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int l, c, h = sizeof(deltat_polynomials);
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do {
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c = (l + h)/2;
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polynomial = deltat_polynomials[c];
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if (y < polynomial[0]) h = c;
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else l = c + 1;
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} while (l < h);
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float u = (y + polynomial[1])/polynomial[2];
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float deltat = 0.0;
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foreach(polynomial; int i; float factor) {
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if (i < 3) continue;
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deltat = deltat * u + factor;
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}
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return deltat;
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}
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//------------------------------------------------------------------------ //! class YMD //! Base (virtual) time period of the Roman-kind of calendar. //! inherits TimeRange //------------------------------------------------------------------------ class YMD { inherit TimeRange;
pike.git/lib/modules/Calendar.pmod/YMD.pike:407:
//! todz "00:00:00 CET" //! todz_iso "00:00:00 UTC+1" //! xtod "00:00:00.000000" //! mod "00:00" //! </pre> //! <tt>[1]</tt> note conflict (think 1 February 2003) //! <br><tt>[2]</tt> language dependent //! <br><tt>[3]</tt> as from the libc function ctime() //! <br><tt>[4]</tt> as specified by the HTTP standard; //! not language dependent.
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//!
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//! The iso variants aim to be compliant with ISO-8601.
string format_iso_ymd() { if (m==CALUNKNOWN) make_month(); if (w==CALUNKNOWN) make_week(); return sprintf("%04d-%02d-%02d (%s) -W%02d-%d (%s)", y,m,md, month_shortname(), w,wd, // fixme - what weekday? week_day_shortname());