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Diffstat (limited to 'src/mscorlib/src/System/Globalization/CalendricalCalculationsHelper.cs')
| -rw-r--r-- | src/mscorlib/src/System/Globalization/CalendricalCalculationsHelper.cs | 414 |
1 files changed, 0 insertions, 414 deletions
diff --git a/src/mscorlib/src/System/Globalization/CalendricalCalculationsHelper.cs b/src/mscorlib/src/System/Globalization/CalendricalCalculationsHelper.cs deleted file mode 100644 index 1113cd58ba..0000000000 --- a/src/mscorlib/src/System/Globalization/CalendricalCalculationsHelper.cs +++ /dev/null @@ -1,414 +0,0 @@ -// Licensed to the .NET Foundation under one or more agreements. -// The .NET Foundation licenses this file to you under the MIT license. -// See the LICENSE file in the project root for more information. - -namespace System.Globalization -{ - using System; - using System.Diagnostics; - using System.Diagnostics.Contracts; - - internal class CalendricalCalculationsHelper - { - const double FullCircleOfArc = 360.0; // 360.0; - const int HalfCircleOfArc = 180; - const double TwelveHours = 0.5; // half a day - const double Noon2000Jan01 = 730120.5; - internal const double MeanTropicalYearInDays = 365.242189; - const double MeanSpeedOfSun = MeanTropicalYearInDays / FullCircleOfArc; - const double LongitudeSpring = 0.0; - const double TwoDegreesAfterSpring = 2.0; - const int SecondsPerDay = 24 * 60 * 60; // 24 hours * 60 minutes * 60 seconds - - const int DaysInUniformLengthCentury = 36525; - const int SecondsPerMinute = 60; - const int MinutesPerDegree = 60; - - static long StartOf1810 = GetNumberOfDays(new DateTime(1810, 1, 1)); - static long StartOf1900Century = GetNumberOfDays(new DateTime(1900, 1, 1)); - - static double[] Coefficients1900to1987 = new double[] { -0.00002, 0.000297, 0.025184, -0.181133, 0.553040, -0.861938, 0.677066, -0.212591 }; - static double[] Coefficients1800to1899 = new double[] { -0.000009, 0.003844, 0.083563, 0.865736, 4.867575, 15.845535, 31.332267, 38.291999, 28.316289, 11.636204, 2.043794 }; - static double[] Coefficients1700to1799 = new double[] { 8.118780842, -0.005092142, 0.003336121, -0.0000266484 }; - static double[] Coefficients1620to1699 = new double[] { 196.58333, -4.0675, 0.0219167 }; - static double[] LambdaCoefficients = new double[] { 280.46645, 36000.76983, 0.0003032 }; - static double[] AnomalyCoefficients = new double[] { 357.52910, 35999.05030, -0.0001559, -0.00000048 }; - static double[] EccentricityCoefficients = new double[] { 0.016708617, -0.000042037, -0.0000001236 }; - static double[] Coefficients = new double[] { Angle(23, 26, 21.448), Angle(0, 0, -46.8150), Angle(0, 0, -0.00059), Angle(0, 0, 0.001813) }; - static double[] CoefficientsA = new double[] { 124.90, -1934.134, 0.002063 }; - static double[] CoefficientsB = new double[] { 201.11, 72001.5377, 0.00057 }; - - static double RadiansFromDegrees(double degree) - { - return degree * Math.PI / 180; - } - - static double SinOfDegree(double degree) - { - return Math.Sin(RadiansFromDegrees(degree)); - } - - static double CosOfDegree(double degree) - { - return Math.Cos(RadiansFromDegrees(degree)); - } - static double TanOfDegree(double degree) - { - return Math.Tan(RadiansFromDegrees(degree)); - } - - public static double Angle(int degrees, int minutes, double seconds) - { - return ((seconds / SecondsPerMinute + minutes) / MinutesPerDegree) + degrees; - } - - static double Obliquity(double julianCenturies) - { - return PolynomialSum(Coefficients, julianCenturies); - } - - internal static long GetNumberOfDays(DateTime date) - { - return date.Ticks / GregorianCalendar.TicksPerDay; - } - - static int GetGregorianYear(double numberOfDays) - { - return new DateTime(Math.Min((long)(Math.Floor(numberOfDays) * GregorianCalendar.TicksPerDay), DateTime.MaxValue.Ticks)).Year; - } - - enum CorrectionAlgorithm - { - Default, - Year1988to2019, - Year1900to1987, - Year1800to1899, - Year1700to1799, - Year1620to1699 - } - - struct EphemerisCorrectionAlgorithmMap - { - public EphemerisCorrectionAlgorithmMap(int year, CorrectionAlgorithm algorithm) - { - _lowestYear = year; - _algorithm = algorithm; - } - - internal int _lowestYear; - internal CorrectionAlgorithm _algorithm; - }; - - static EphemerisCorrectionAlgorithmMap[] EphemerisCorrectionTable = new EphemerisCorrectionAlgorithmMap[] - { - // lowest year that starts algorithm, algorithm to use - new EphemerisCorrectionAlgorithmMap(2020, CorrectionAlgorithm.Default), - new EphemerisCorrectionAlgorithmMap(1988, CorrectionAlgorithm.Year1988to2019), - new EphemerisCorrectionAlgorithmMap(1900, CorrectionAlgorithm.Year1900to1987), - new EphemerisCorrectionAlgorithmMap(1800, CorrectionAlgorithm.Year1800to1899), - new EphemerisCorrectionAlgorithmMap(1700, CorrectionAlgorithm.Year1700to1799), - new EphemerisCorrectionAlgorithmMap(1620, CorrectionAlgorithm.Year1620to1699), - new EphemerisCorrectionAlgorithmMap(int.MinValue, CorrectionAlgorithm.Default) // default must be last - }; - - static double Reminder(double divisor, double dividend) - { - double whole = Math.Floor(divisor / dividend); - return divisor - (dividend * whole); - } - - static double NormalizeLongitude(double longitude) - { - longitude = Reminder(longitude, FullCircleOfArc); - if (longitude < 0) - { - longitude += FullCircleOfArc; - } - return longitude; - } - - static public double AsDayFraction(double longitude) - { - return longitude / FullCircleOfArc; - } - - static double PolynomialSum(double[] coefficients, double indeterminate) - { - double sum = coefficients[0]; - double indeterminateRaised = 1; - for (int i=1; i<coefficients.Length; i++) - { - indeterminateRaised *= indeterminate; - sum += (coefficients[i] * indeterminateRaised); - } - - return sum; - } - - static double CenturiesFrom1900(int gregorianYear) - { - long july1stOfYear = GetNumberOfDays(new DateTime(gregorianYear, 7, 1)); - return (double) (july1stOfYear - StartOf1900Century) / DaysInUniformLengthCentury; - } - - // the following formulas defines a polynomial function which gives us the amount that the earth is slowing down for specific year ranges - static double DefaultEphemerisCorrection(int gregorianYear) - { - Debug.Assert(gregorianYear < 1620 || 2020 <= gregorianYear); - long january1stOfYear = GetNumberOfDays(new DateTime(gregorianYear, 1, 1)); - double daysSinceStartOf1810 = january1stOfYear - StartOf1810; - double x = TwelveHours + daysSinceStartOf1810; - return ((Math.Pow(x, 2) / 41048480) - 15) / SecondsPerDay; - } - - static double EphemerisCorrection1988to2019(int gregorianYear) - { - Debug.Assert(1988 <= gregorianYear && gregorianYear <= 2019); - return (double)(gregorianYear - 1933) / SecondsPerDay; - } - - static double EphemerisCorrection1900to1987(int gregorianYear) - { - Debug.Assert(1900 <= gregorianYear && gregorianYear <= 1987); - double centuriesFrom1900 = CenturiesFrom1900(gregorianYear); - return PolynomialSum(Coefficients1900to1987, centuriesFrom1900); - } - - static double EphemerisCorrection1800to1899(int gregorianYear) - { - Debug.Assert(1800 <= gregorianYear && gregorianYear <= 1899); - double centuriesFrom1900 = CenturiesFrom1900(gregorianYear); - return PolynomialSum(Coefficients1800to1899, centuriesFrom1900); - } - - static double EphemerisCorrection1700to1799(int gregorianYear) - { - Debug.Assert(1700 <= gregorianYear && gregorianYear <= 1799); - double yearsSince1700 = gregorianYear - 1700; - return PolynomialSum(Coefficients1700to1799, yearsSince1700) / SecondsPerDay; - } - - static double EphemerisCorrection1620to1699(int gregorianYear) - { - Debug.Assert(1620 <= gregorianYear && gregorianYear <= 1699); - double yearsSince1600 = gregorianYear - 1600; - return PolynomialSum(Coefficients1620to1699, yearsSince1600) / SecondsPerDay; - } - - // ephemeris-correction: correction to account for the slowing down of the rotation of the earth - static double EphemerisCorrection(double time) - { - int year = GetGregorianYear(time); - foreach (EphemerisCorrectionAlgorithmMap map in EphemerisCorrectionTable) - { - if (map._lowestYear <= year) - { - switch (map._algorithm) - { - case CorrectionAlgorithm.Default: return DefaultEphemerisCorrection(year); - case CorrectionAlgorithm.Year1988to2019: return EphemerisCorrection1988to2019(year); - case CorrectionAlgorithm.Year1900to1987: return EphemerisCorrection1900to1987(year); - case CorrectionAlgorithm.Year1800to1899: return EphemerisCorrection1800to1899(year); - case CorrectionAlgorithm.Year1700to1799: return EphemerisCorrection1700to1799(year); - case CorrectionAlgorithm.Year1620to1699: return EphemerisCorrection1620to1699(year); - } - - break; // break the loop and assert eventually - } - } - - Debug.Assert(false, "Not expected to come here"); - return DefaultEphemerisCorrection(year); - } - - static public double JulianCenturies(double moment) - { - double dynamicalMoment = moment + EphemerisCorrection(moment); - return (dynamicalMoment - Noon2000Jan01) / DaysInUniformLengthCentury; - } - - static bool IsNegative(double value) - { - return Math.Sign(value) == -1; - } - - static double CopySign(double value, double sign) - { - return (IsNegative(value) == IsNegative(sign)) ? value : -value; - } - - // equation-of-time; approximate the difference between apparent solar time and mean solar time - // formal definition is EOT = GHA - GMHA - // GHA is the Greenwich Hour Angle of the apparent (actual) Sun - // GMHA is the Greenwich Mean Hour Angle of the mean (fictitious) Sun - // http://www.esrl.noaa.gov/gmd/grad/solcalc/ - // http://en.wikipedia.org/wiki/Equation_of_time - static double EquationOfTime(double time) - { - double julianCenturies = JulianCenturies(time); - double lambda = PolynomialSum(LambdaCoefficients, julianCenturies); - double anomaly = PolynomialSum(AnomalyCoefficients, julianCenturies); - double eccentricity = PolynomialSum(EccentricityCoefficients, julianCenturies); - - double epsilon = Obliquity(julianCenturies); - double tanHalfEpsilon = TanOfDegree(epsilon / 2); - double y = tanHalfEpsilon * tanHalfEpsilon; - - double dividend = ((y * SinOfDegree(2 * lambda)) - - (2 * eccentricity * SinOfDegree(anomaly)) - + (4 * eccentricity * y * SinOfDegree(anomaly) * CosOfDegree(2 * lambda)) - - (0.5 * Math.Pow(y, 2) * SinOfDegree(4 * lambda)) - - (1.25 * Math.Pow(eccentricity, 2) * SinOfDegree(2 * anomaly))); - double divisor = 2 * Math.PI; - double equation = dividend / divisor; - - // approximation of equation of time is not valid for dates that are many millennia in the past or future - // thus limited to a half day - return CopySign(Math.Min(Math.Abs(equation), TwelveHours), equation); - } - - static double AsLocalTime(double apparentMidday, double longitude) - { - // slightly inaccurate since equation of time takes mean time not apparent time as its argument, but the difference is negligible - double universalTime = apparentMidday - AsDayFraction(longitude); - return apparentMidday - EquationOfTime(universalTime); - } - - // midday - static public double Midday(double date, double longitude) - { - return AsLocalTime(date+TwelveHours, longitude) - AsDayFraction(longitude); - } - - static double InitLongitude(double longitude) - { - return NormalizeLongitude(longitude + HalfCircleOfArc) - HalfCircleOfArc; - } - - // midday-in-tehran - static public double MiddayAtPersianObservationSite(double date) - { - return Midday(date, InitLongitude(52.5)); // 52.5 degrees east - longitude of UTC+3:30 which defines Iranian Standard Time - } - - static double PeriodicTerm(double julianCenturies, int x, double y, double z) - { - return x * SinOfDegree(y + z * julianCenturies); - } - - static double SumLongSequenceOfPeriodicTerms(double julianCenturies) - { - double sum = 0.0; - sum += PeriodicTerm(julianCenturies, 403406, 270.54861, 0.9287892); - sum += PeriodicTerm(julianCenturies, 195207, 340.19128, 35999.1376958); - sum += PeriodicTerm(julianCenturies, 119433, 63.91854, 35999.4089666); - sum += PeriodicTerm(julianCenturies, 112392, 331.2622, 35998.7287385); - sum += PeriodicTerm(julianCenturies, 3891, 317.843, 71998.20261); - sum += PeriodicTerm(julianCenturies, 2819, 86.631, 71998.4403); - sum += PeriodicTerm(julianCenturies, 1721, 240.052, 36000.35726); - sum += PeriodicTerm(julianCenturies, 660, 310.26, 71997.4812); - sum += PeriodicTerm(julianCenturies, 350, 247.23, 32964.4678); - sum += PeriodicTerm(julianCenturies, 334, 260.87, -19.441); - sum += PeriodicTerm(julianCenturies, 314, 297.82, 445267.1117); - sum += PeriodicTerm(julianCenturies, 268, 343.14, 45036.884); - sum += PeriodicTerm(julianCenturies, 242, 166.79, 3.1008); - sum += PeriodicTerm(julianCenturies, 234, 81.53, 22518.4434); - sum += PeriodicTerm(julianCenturies, 158, 3.5, -19.9739); - sum += PeriodicTerm(julianCenturies, 132, 132.75, 65928.9345); - sum += PeriodicTerm(julianCenturies, 129, 182.95, 9038.0293); - sum += PeriodicTerm(julianCenturies, 114, 162.03, 3034.7684); - sum += PeriodicTerm(julianCenturies, 99, 29.8, 33718.148); - sum += PeriodicTerm(julianCenturies, 93, 266.4, 3034.448); - sum += PeriodicTerm(julianCenturies, 86, 249.2, -2280.773); - sum += PeriodicTerm(julianCenturies, 78, 157.6, 29929.992); - sum += PeriodicTerm(julianCenturies, 72, 257.8, 31556.493); - sum += PeriodicTerm(julianCenturies, 68, 185.1, 149.588); - sum += PeriodicTerm(julianCenturies, 64, 69.9, 9037.75); - sum += PeriodicTerm(julianCenturies, 46, 8.0, 107997.405); - sum += PeriodicTerm(julianCenturies, 38, 197.1, -4444.176); - sum += PeriodicTerm(julianCenturies, 37, 250.4, 151.771); - sum += PeriodicTerm(julianCenturies, 32, 65.3, 67555.316); - sum += PeriodicTerm(julianCenturies, 29, 162.7, 31556.08); - sum += PeriodicTerm(julianCenturies, 28, 341.5, -4561.54); - sum += PeriodicTerm(julianCenturies, 27, 291.6, 107996.706); - sum += PeriodicTerm(julianCenturies, 27, 98.5, 1221.655); - sum += PeriodicTerm(julianCenturies, 25, 146.7, 62894.167); - sum += PeriodicTerm(julianCenturies, 24, 110.0, 31437.369); - sum += PeriodicTerm(julianCenturies, 21, 5.2, 14578.298); - sum += PeriodicTerm(julianCenturies, 21, 342.6, -31931.757); - sum += PeriodicTerm(julianCenturies, 20, 230.9, 34777.243); - sum += PeriodicTerm(julianCenturies, 18, 256.1, 1221.999); - sum += PeriodicTerm(julianCenturies, 17, 45.3, 62894.511); - sum += PeriodicTerm(julianCenturies, 14, 242.9, -4442.039); - sum += PeriodicTerm(julianCenturies, 13, 115.2, 107997.909); - sum += PeriodicTerm(julianCenturies, 13, 151.8, 119.066); - sum += PeriodicTerm(julianCenturies, 13, 285.3, 16859.071); - sum += PeriodicTerm(julianCenturies, 12, 53.3, -4.578); - sum += PeriodicTerm(julianCenturies, 10, 126.6, 26895.292); - sum += PeriodicTerm(julianCenturies, 10, 205.7, -39.127); - sum += PeriodicTerm(julianCenturies, 10, 85.9, 12297.536); - sum += PeriodicTerm(julianCenturies, 10, 146.1, 90073.778); - return sum; - } - - static double Aberration(double julianCenturies) - { - return (0.0000974 * CosOfDegree(177.63 + (35999.01848 * julianCenturies))) - 0.005575; - } - - static double Nutation(double julianCenturies) - { - double a = PolynomialSum(CoefficientsA, julianCenturies); - double b = PolynomialSum(CoefficientsB, julianCenturies); - return (-0.004778 * SinOfDegree(a)) - (0.0003667 * SinOfDegree(b)); - } - - static public double Compute(double time) - { - double julianCenturies = JulianCenturies(time); - double lambda = 282.7771834 - + (36000.76953744 * julianCenturies) - + (0.000005729577951308232 * SumLongSequenceOfPeriodicTerms(julianCenturies)); - - double longitude = lambda + Aberration(julianCenturies) + Nutation(julianCenturies); - return InitLongitude(longitude); - } - - static public double AsSeason(double longitude) - { - return (longitude < 0) ? (longitude + FullCircleOfArc) : longitude; - } - - static double EstimatePrior(double longitude, double time) - { - double timeSunLastAtLongitude = time - (MeanSpeedOfSun * AsSeason(InitLongitude(Compute(time) - longitude))); - double longitudeErrorDelta = InitLongitude(Compute(timeSunLastAtLongitude) - longitude); - return Math.Min(time, timeSunLastAtLongitude - (MeanSpeedOfSun * longitudeErrorDelta)); - } - - // persian-new-year-on-or-before - // number of days is the absolute date. The absolute date is the number of days from January 1st, 1 A.D. - // 1/1/0001 is absolute date 1. - internal static long PersianNewYearOnOrBefore(long numberOfDays) - { - double date = (double) numberOfDays; - - double approx = EstimatePrior(LongitudeSpring, MiddayAtPersianObservationSite(date)); - long lowerBoundNewYearDay = (long) Math.Floor(approx) - 1; - long upperBoundNewYearDay = lowerBoundNewYearDay + 3; // estimate is generally within a day of the actual occurrance (at the limits, the error expands, since the calculations rely on the mean tropical year which changes...) - long day = lowerBoundNewYearDay; - for (; day != upperBoundNewYearDay; ++day) - { - double midday = MiddayAtPersianObservationSite((double) day); - double l = Compute(midday); - if ((LongitudeSpring <= l) && (l <= TwoDegreesAfterSpring)) - { - break; - } - } - Debug.Assert(day != upperBoundNewYearDay); - - return day - 1; - } - } -} |