From cb9d9b4b16c7de668772a93899f65ee313efac91 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Henrik=20Grubbstr=C3=B6m=20=28Grubba=29?=
<grubba@grubba.org>
Date: Sun, 9 Sep 2012 21:06:56 +0200
Subject: [PATCH] Calendar.Event: Compensate for leap seconds.
The solar event calculations now compensate for the difference between
TDT (Terrestrial Dynamical Time) and UTC.
Also fixes some AutoDoc mk II markup bugs.
---
lib/modules/Calendar.pmod/Event.pmod | 99 +++++++++++++++++++++++++---
1 file changed, 91 insertions(+), 8 deletions(-)
diff --git a/lib/modules/Calendar.pmod/Event.pmod b/lib/modules/Calendar.pmod/Event.pmod
index 5437abab20..cb0ff45659 100644
--- a/lib/modules/Calendar.pmod/Event.pmod
+++ b/lib/modules/Calendar.pmod/Event.pmod
@@ -876,14 +876,14 @@ class Solar(int|void event_type)
inherit Day_Event;
//! @array
- //! @item
+ //! @elem array(float) 0..
//! @array
- //! @item 0 amplitude
- //! Days.
- //! @item 1 phase
- //! Radians @ year 2000.
- //! @item 2 period
- //! Radians/Year.
+ //! @elem float 0
+ //! Amplitude in days.
+ //! @elem float 1
+ //! Cosine phase in radians in year 2000.
+ //! @elem float 2
+ //! Period in radians/year.
//! @endarray
//! @endarray
protected constant periodic_table = ({
@@ -913,6 +913,88 @@ class Solar(int|void event_type)
({ 0.00008, 0.2697, 294.24635, }),
});
+ //! Polynomial terms for calculating the difference between TDT and UTC.
+ //!
+ //! The polynomials have been taken from NASA:
+ //! @url{http://eclipse.gsfc.nasa.gov/SEhelp/deltatpoly2004.html@}
+ //!
+ //! Each entry is an @expr{array(float)@}:
+ //! @array
+ //! @elem float 0
+ //! End year for the range.
+ //! @elem float 1
+ //! Year offset.
+ //! @elem float 2
+ //! Year divisor.
+ //! @elem float 3..
+ //! Polynomial factors with the highest exponent first.
+ //! @endarray
+ protected constant deltat_polynomials = ({
+ ({ -500.0, -1820.0, 100.0,
+ -20.0, 0.0, 32.0, }),
+ ({ 500.0, 0.0, 100.0,
+ 0.0090316521, 0.022174192, -0.1798452,
+ -5.952053, 33.78311, -1014.41, 10583.6, }),
+ ({ 1600.0, -1000.0, 100.0,
+ 0.0083572073, -0.005050998, -0.8503463,
+ 0.319781, 71.23472, -556.01, 1574.2, }),
+ ({ 1700.0, -1600.0, 1.0,
+ 0.000140272128, -0.01532, -0.9808, 120.0, }),
+ ({ 1800.0, -1700.0, 1.0,
+ 0.000000851788756, 0.00013336, -0.0059285, 0.1603, 8.83, }),
+ ({ 1860.0, -1800.0, 1.0,
+ 0.000000000875, -0.0000001699, 0.0000121272, -0.00037436,
+ 0.0041116, 0.0068612, -0.332447, 13.72, }),
+ ({ 1900.0, -1860.0, 1.0,
+ 0.000004288643, -0.0004473624, 0.01680668, -0.251754, 0.5737, 7.62, }),
+ ({ 1920.0, -1900.0, 1.0,
+ -0.000197, 0.0061966, -0.0598939, 1.494119, -2.79, }),
+ ({ 1941.0, -1920.0, 1.0,
+ 0.0020936, -0.076100, 0.84493, 21.20, }),
+ ({ 1961.0, -1950.0, 1.0,
+ 0.0003926188, 0.0042918455, 0.407, 29.07, }),
+ ({ 1986.0, -1975.0, 1.0,
+ 0.001392758, 0.0038461538, 1.067, 45.45, }),
+ ({ 2005.0, -2000.0, 1.0,
+ 0.00002373599, 0.000651814, 0.0017275, -0.060374, 0.3345, 63.86, }),
+ ({ 2050.0, -2000.0, 1.0,
+ 0.005589, 0.32217, 62.92 }),
+ ({ 2150.0, -1820.0, 100.0,
+ 32.0-185.724, 56.28, -20.0, }),
+ ({ Math.inf, -1820.0, 100.0,
+ 32.0, 0.0, -20.0, }),
+ });
+
+ //! Terrestrial Dynamical Time difference from standard time.
+ //!
+ //! @returns
+ //! Difference between TDT and UTC in seconds at the
+ //! specified time.
+ int deltat(int unadjusted_utc)
+ {
+ // Approximation of the year. This ought to be good enough for
+ // most purposes given the uncertainty in the table values.
+ // 31556952 == 365.2425 * 24 * 60 * 60.
+ float y = 1970.0 + unadjusted_utc/31556952.0;
+
+ array(float) polynomial;
+ int l, c, h = sizeof(deltat_polynomials);
+ do {
+ c = (l + h)/2;
+ polynomial = deltat_polynomials[c];
+ if (y < polynomial[0]) h = c;
+ else l = c + 1;
+ } while (l < h);
+ float u = (y + polynomial[1])/polynomial[2];
+
+ float deltat = 0.0;
+ foreach(polynomial; int i; float factor) {
+ if (i < 3) continue;
+ deltat = deltat * u + factor;
+ }
+ return (int)round(deltat);
+ }
+
//! Calculate the next event.
//!
//! Based on Meeus Astronomical Algorithms Chapter 27.
@@ -1035,7 +1117,8 @@ class Solar(int|void event_type)
}
// Convert into an UTC timestamp.
- return (new_jd - 2440588)*86400 + (int)(offset * 86400.0);
+ int utc = (new_jd - 2440588)*86400 + (int)(offset * 86400.0);
+ return utc - deltat(utc);
}
Calendar.TimeRanges.TimeRange next(void|Calendar.TimeRanges.TimeRange from,
--
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