762 lines
24 KiB
C++
762 lines
24 KiB
C++
/************************************************************************
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* Copyright (C) 1996-2003, International Business Machines Corporation *
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* and others. All Rights Reserved. *
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************************************************************************
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* 2003-nov-07 srl Port from Java
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*/
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#ifndef ASTRO_H
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#define ASTRO_H
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#include "unicode/utypes.h"
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#if !UCONFIG_NO_FORMATTING
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#include "gregoimp.h" // for Math
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#include "unicode/unistr.h"
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/**
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* <code>CalendarAstronomer</code> is a class that can perform the calculations to
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* determine the positions of the sun and moon, the time of sunrise and
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* sunset, and other astronomy-related data. The calculations it performs
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* are in some cases quite complicated, and this utility class saves you
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* the trouble of worrying about them.
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* <p>
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* The measurement of time is a very important part of astronomy. Because
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* astronomical bodies are constantly in motion, observations are only valid
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* at a given moment in time. Accordingly, each <code>CalendarAstronomer</code>
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* object has a <code>time</code> property that determines the date
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* and time for which its calculations are performed. You can set and
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* retrieve this property with {@link #setDate setDate}, {@link #getDate getDate}
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* and related methods.
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* <p>
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* Almost all of the calculations performed by this class, or by any
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* astronomer, are approximations to various degrees of accuracy. The
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* calculations in this class are mostly modelled after those described
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* in the book
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* <a href="http://www.amazon.com/exec/obidos/ISBN=0521356997" target="_top">
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* Practical Astronomy With Your Calculator</a>, by Peter J.
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* Duffett-Smith, Cambridge University Press, 1990. This is an excellent
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* book, and if you want a greater understanding of how these calculations
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* are performed it a very good, readable starting point.
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* <p>
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* <strong>WARNING:</strong> This class is very early in its development, and
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* it is highly likely that its API will change to some degree in the future.
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* At the moment, it basically does just enough to support {@link IslamicCalendar}
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* and {@link ChineseCalendar}.
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*
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* @author Laura Werner
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* @author Alan Liu
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* @internal
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*/
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class U_I18N_API CalendarAstronomer : public UMemory {
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public:
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// some classes
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public:
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/**
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* Represents the position of an object in the sky relative to the ecliptic,
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* the plane of the earth's orbit around the Sun.
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* This is a spherical coordinate system in which the latitude
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* specifies the position north or south of the plane of the ecliptic.
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* The longitude specifies the position along the ecliptic plane
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* relative to the "First Point of Aries", which is the Sun's position in the sky
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* at the Vernal Equinox.
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* <p>
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* Note that Ecliptic objects are immutable and cannot be modified
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* once they are constructed. This allows them to be passed and returned by
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* value without worrying about whether other code will modify them.
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*
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* @see CalendarAstronomer.Equatorial
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* @see CalendarAstronomer.Horizon
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* @internal
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*/
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class U_I18N_API Ecliptic : public UMemory {
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public:
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/**
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* Constructs an Ecliptic coordinate object.
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* <p>
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* @param lat The ecliptic latitude, measured in radians.
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* @param lon The ecliptic longitude, measured in radians.
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* @internal
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*/
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Ecliptic(double lat = 0, double lon = 0) {
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latitude = lat;
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longitude = lon;
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}
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/**
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* Setter for Ecliptic Coordinate object
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* @param lat The ecliptic latitude, measured in radians.
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* @param lon The ecliptic longitude, measured in radians.
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* @internal
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*/
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void set(double lat, double lon) {
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latitude = lat;
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longitude = lon;
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}
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/**
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* Return a string representation of this object
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* @internal
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*/
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UnicodeString toString() const;
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/**
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* The ecliptic latitude, in radians. This specifies an object's
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* position north or south of the plane of the ecliptic,
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* with positive angles representing north.
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* @internal
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*/
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double latitude;
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/**
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* The ecliptic longitude, in radians.
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* This specifies an object's position along the ecliptic plane
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* relative to the "First Point of Aries", which is the Sun's position
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* in the sky at the Vernal Equinox,
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* with positive angles representing east.
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* <p>
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* A bit of trivia: the first point of Aries is currently in the
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* constellation Pisces, due to the precession of the earth's axis.
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* @internal
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*/
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double longitude;
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};
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/**
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* Represents the position of an
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* object in the sky relative to the plane of the earth's equator.
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* The <i>Right Ascension</i> specifies the position east or west
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* along the equator, relative to the sun's position at the vernal
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* equinox. The <i>Declination</i> is the position north or south
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* of the equatorial plane.
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* <p>
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* Note that Equatorial objects are immutable and cannot be modified
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* once they are constructed. This allows them to be passed and returned by
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* value without worrying about whether other code will modify them.
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*
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* @see CalendarAstronomer.Ecliptic
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* @see CalendarAstronomer.Horizon
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* @internal
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*/
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class U_I18N_API Equatorial : public UMemory {
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public:
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/**
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* Constructs an Equatorial coordinate object.
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* <p>
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* @param asc The right ascension, measured in radians.
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* @param dec The declination, measured in radians.
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* @internal
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*/
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Equatorial(double asc = 0, double dec = 0)
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: ascension(asc), declination(dec) { }
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/**
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* Setter
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* @param asc The right ascension, measured in radians.
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* @param dec The declination, measured in radians.
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* @internal
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*/
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void set(double asc, double dec) {
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ascension = asc;
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declination = dec;
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}
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/**
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* Return a string representation of this object, with the
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* angles measured in degrees.
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* @internal
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*/
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UnicodeString toString() const;
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/**
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* Return a string representation of this object with the right ascension
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* measured in hours, minutes, and seconds.
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* @internal
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*/
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//String toHmsString() {
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//return radToHms(ascension) + "," + radToDms(declination);
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//}
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/**
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* The right ascension, in radians.
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* This is the position east or west along the equator
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* relative to the sun's position at the vernal equinox,
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* with positive angles representing East.
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* @internal
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*/
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double ascension;
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/**
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* The declination, in radians.
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* This is the position north or south of the equatorial plane,
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* with positive angles representing north.
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* @internal
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*/
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double declination;
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};
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/**
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* Represents the position of an object in the sky relative to
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* the local horizon.
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* The <i>Altitude</i> represents the object's elevation above the horizon,
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* with objects below the horizon having a negative altitude.
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* The <i>Azimuth</i> is the geographic direction of the object from the
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* observer's position, with 0 representing north. The azimuth increases
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* clockwise from north.
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* <p>
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* Note that Horizon objects are immutable and cannot be modified
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* once they are constructed. This allows them to be passed and returned by
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* value without worrying about whether other code will modify them.
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*
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* @see CalendarAstronomer.Ecliptic
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* @see CalendarAstronomer.Equatorial
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* @internal
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*/
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class U_I18N_API Horizon : public UMemory {
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public:
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/**
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* Constructs a Horizon coordinate object.
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* <p>
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* @param alt The altitude, measured in radians above the horizon.
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* @param azim The azimuth, measured in radians clockwise from north.
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* @internal
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*/
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Horizon(double alt=0, double azim=0)
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: altitude(alt), azimuth(azim) { }
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/**
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* Setter for Ecliptic Coordinate object
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* @param alt The altitude, measured in radians above the horizon.
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* @param azim The azimuth, measured in radians clockwise from north.
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* @internal
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*/
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void set(double alt, double azim) {
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altitude = alt;
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azimuth = azim;
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}
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/**
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* Return a string representation of this object, with the
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* angles measured in degrees.
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* @internal
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*/
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UnicodeString toString() const;
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/**
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* The object's altitude above the horizon, in radians.
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* @internal
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*/
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double altitude;
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/**
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* The object's direction, in radians clockwise from north.
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* @internal
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*/
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double azimuth;
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};
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public:
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//-------------------------------------------------------------------------
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// Assorted private data used for conversions
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//-------------------------------------------------------------------------
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// My own copies of these so compilers are more likely to optimize them away
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static const double PI;
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/**
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* The average number of solar days from one new moon to the next. This is the time
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* it takes for the moon to return the same ecliptic longitude as the sun.
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* It is longer than the sidereal month because the sun's longitude increases
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* during the year due to the revolution of the earth around the sun.
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* Approximately 29.53.
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*
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* @see #SIDEREAL_MONTH
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* @internal
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* @deprecated ICU 2.4. This class may be removed or modified.
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*/
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static const double SYNODIC_MONTH;
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//-------------------------------------------------------------------------
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// Constructors
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//-------------------------------------------------------------------------
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/**
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* Construct a new <code>CalendarAstronomer</code> object that is initialized to
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* the current date and time.
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* @internal
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*/
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CalendarAstronomer();
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/**
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* Construct a new <code>CalendarAstronomer</code> object that is initialized to
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* the specified date and time.
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* @internal
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*/
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CalendarAstronomer(UDate d);
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/**
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* Construct a new <code>CalendarAstronomer</code> object with the given
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* latitude and longitude. The object's time is set to the current
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* date and time.
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* <p>
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* @param longitude The desired longitude, in <em>degrees</em> east of
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* the Greenwich meridian.
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*
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* @param latitude The desired latitude, in <em>degrees</em>. Positive
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* values signify North, negative South.
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*
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* @see java.util.Date#getTime()
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* @internal
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*/
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CalendarAstronomer(double longitude, double latitude);
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/**
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* Destructor
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* @internal
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*/
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~CalendarAstronomer();
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//-------------------------------------------------------------------------
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// Time and date getters and setters
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//-------------------------------------------------------------------------
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/**
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* Set the current date and time of this <code>CalendarAstronomer</code> object. All
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* astronomical calculations are performed based on this time setting.
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*
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* @param aTime the date and time, expressed as the number of milliseconds since
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* 1/1/1970 0:00 GMT (Gregorian).
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*
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* @see #setDate
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* @see #getTime
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* @internal
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*/
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void setTime(UDate aTime);
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/**
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* Set the current date and time of this <code>CalendarAstronomer</code> object. All
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* astronomical calculations are performed based on this time setting.
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*
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* @param aTime the date and time, expressed as the number of milliseconds since
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* 1/1/1970 0:00 GMT (Gregorian).
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*
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* @see #getTime
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* @internal
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*/
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void setDate(UDate aDate) { setTime(aDate); }
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/**
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* Set the current date and time of this <code>CalendarAstronomer</code> object. All
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* astronomical calculations are performed based on this time setting.
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*
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* @param jdn the desired time, expressed as a "julian day number",
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* which is the number of elapsed days since
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* 1/1/4713 BC (Julian), 12:00 GMT. Note that julian day
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* numbers start at <em>noon</em>. To get the jdn for
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* the corresponding midnight, subtract 0.5.
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*
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* @see #getJulianDay
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* @see #JULIAN_EPOCH_MS
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* @internal
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*/
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void setJulianDay(double jdn);
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/**
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* Get the current time of this <code>CalendarAstronomer</code> object,
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* represented as the number of milliseconds since
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* 1/1/1970 AD 0:00 GMT (Gregorian).
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*
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* @see #setTime
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* @see #getDate
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* @internal
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*/
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UDate getTime();
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/**
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* Get the current time of this <code>CalendarAstronomer</code> object,
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* expressed as a "julian day number", which is the number of elapsed
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* days since 1/1/4713 BC (Julian), 12:00 GMT.
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*
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* @see #setJulianDay
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* @see #JULIAN_EPOCH_MS
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* @internal
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*/
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double getJulianDay();
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/**
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* Return this object's time expressed in julian centuries:
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* the number of centuries after 1/1/1900 AD, 12:00 GMT
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*
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* @see #getJulianDay
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* @internal
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*/
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double getJulianCentury();
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/**
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* Returns the current Greenwich sidereal time, measured in hours
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* @internal
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*/
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double getGreenwichSidereal();
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private:
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double getSiderealOffset();
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public:
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/**
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* Returns the current local sidereal time, measured in hours
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* @internal
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*/
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double getLocalSidereal();
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/**
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* Converts local sidereal time to Universal Time.
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*
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* @param lst The Local Sidereal Time, in hours since sidereal midnight
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* on this object's current date.
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*
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* @return The corresponding Universal Time, in milliseconds since
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* 1 Jan 1970, GMT.
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*/
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//private:
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double lstToUT(double lst);
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/**
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*
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* Convert from ecliptic to equatorial coordinates.
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*
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* @param ecliptic The ecliptic
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* @param result Fillin result
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* @return reference to result
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*/
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Equatorial& eclipticToEquatorial(Equatorial& result, const Ecliptic& ecliptic);
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/**
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* Convert from ecliptic to equatorial coordinates.
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*
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* @param eclipLong The ecliptic longitude
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* @param eclipLat The ecliptic latitude
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*
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* @return The corresponding point in equatorial coordinates.
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* @internal
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*/
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Equatorial& eclipticToEquatorial(Equatorial& result, double eclipLong, double eclipLat);
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/**
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* Convert from ecliptic longitude to equatorial coordinates.
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*
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* @param eclipLong The ecliptic longitude
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*
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* @return The corresponding point in equatorial coordinates.
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* @internal
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*/
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Equatorial& eclipticToEquatorial(Equatorial& result, double eclipLong) ;
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/**
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* @internal
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*/
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Horizon& eclipticToHorizon(Horizon& result, double eclipLong) ;
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//-------------------------------------------------------------------------
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// The Sun
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//-------------------------------------------------------------------------
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/**
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* The longitude of the sun at the time specified by this object.
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* The longitude is measured in radians along the ecliptic
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* from the "first point of Aries," the point at which the ecliptic
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* crosses the earth's equatorial plane at the vernal equinox.
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* <p>
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* Currently, this method uses an approximation of the two-body Kepler's
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* equation for the earth and the sun. It does not take into account the
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* perturbations caused by the other planets, the moon, etc.
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* @internal
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*/
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double getSunLongitude();
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/**
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* TODO Make this public when the entire class is package-private.
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*/
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/*public*/ void getSunLongitude(double julianDay, double &longitude, double &meanAnomaly);
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/**
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* The position of the sun at this object's current date and time,
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* in equatorial coordinates.
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* @param result fillin for the result
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* @internal
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*/
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Equatorial& getSunPosition(Equatorial& result);
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public:
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/**
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* Constant representing the vernal equinox.
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* For use with {@link #getSunTime getSunTime}.
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* Note: In this case, "vernal" refers to the northern hemisphere's seasons.
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* @internal
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*/
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static double VERNAL_EQUINOX();
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/**
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* Constant representing the summer solstice.
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* For use with {@link #getSunTime getSunTime}.
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* Note: In this case, "summer" refers to the northern hemisphere's seasons.
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* @internal
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*/
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static double SUMMER_SOLSTICE();
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/**
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* Constant representing the autumnal equinox.
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* For use with {@link #getSunTime getSunTime}.
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* Note: In this case, "autumn" refers to the northern hemisphere's seasons.
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* @internal
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*/
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static double AUTUMN_EQUINOX();
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/**
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* Constant representing the winter solstice.
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* For use with {@link #getSunTime getSunTime}.
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* Note: In this case, "winter" refers to the northern hemisphere's seasons.
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* @internal
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*/
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static double WINTER_SOLSTICE();
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/**
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* Find the next time at which the sun's ecliptic longitude will have
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* the desired value.
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* @internal
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*/
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UDate getSunTime(double desired, UBool next);
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/**
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* Returns the time (GMT) of sunrise or sunset on the local date to which
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* this calendar is currently set.
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*
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* NOTE: This method only works well if this object is set to a
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* time near local noon. Because of variations between the local
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* official time zone and the geographic longitude, the
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* computation can flop over into an adjacent day if this object
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* is set to a time near local midnight.
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*
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* @internal
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*/
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UDate getSunRiseSet(UBool rise);
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//-------------------------------------------------------------------------
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// The Moon
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//-------------------------------------------------------------------------
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/**
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* The position of the moon at the time set on this
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* object, in equatorial coordinates.
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* @internal
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* @return const reference to internal field of calendar astronomer. Do not use outside of the lifetime of this astronomer.
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*/
|
|
const Equatorial& getMoonPosition();
|
|
|
|
/**
|
|
* The "age" of the moon at the time specified in this object.
|
|
* This is really the angle between the
|
|
* current ecliptic longitudes of the sun and the moon,
|
|
* measured in radians.
|
|
*
|
|
* @see #getMoonPhase
|
|
* @internal
|
|
*/
|
|
double getMoonAge();
|
|
|
|
/**
|
|
* Calculate the phase of the moon at the time set in this object.
|
|
* The returned phase is a <code>double</code> in the range
|
|
* <code>0 <= phase < 1</code>, interpreted as follows:
|
|
* <ul>
|
|
* <li>0.00: New moon
|
|
* <li>0.25: First quarter
|
|
* <li>0.50: Full moon
|
|
* <li>0.75: Last quarter
|
|
* </ul>
|
|
*
|
|
* @see #getMoonAge
|
|
* @internal
|
|
*/
|
|
double getMoonPhase();
|
|
|
|
class U_I18N_API MoonAge : public UMemory {
|
|
public:
|
|
MoonAge(double l)
|
|
: value(l) { }
|
|
void set(double l) { value = l; }
|
|
double value;
|
|
};
|
|
|
|
/**
|
|
* Constant representing a new moon.
|
|
* For use with {@link #getMoonTime getMoonTime}
|
|
* @internal
|
|
*/
|
|
static const MoonAge NEW_MOON();
|
|
|
|
/**
|
|
* Constant representing the moon's first quarter.
|
|
* For use with {@link #getMoonTime getMoonTime}
|
|
* @internal
|
|
*/
|
|
static const MoonAge FIRST_QUARTER();
|
|
|
|
/**
|
|
* Constant representing a full moon.
|
|
* For use with {@link #getMoonTime getMoonTime}
|
|
* @internal
|
|
*/
|
|
static const MoonAge FULL_MOON();
|
|
|
|
/**
|
|
* Constant representing the moon's last quarter.
|
|
* For use with {@link #getMoonTime getMoonTime}
|
|
* @internal
|
|
*/
|
|
static const MoonAge LAST_QUARTER();
|
|
|
|
/**
|
|
* Find the next or previous time at which the Moon's ecliptic
|
|
* longitude will have the desired value.
|
|
* <p>
|
|
* @param desired The desired longitude.
|
|
* @param next <tt>true</tt> if the next occurrance of the phase
|
|
* is desired, <tt>false</tt> for the previous occurrance.
|
|
* @internal
|
|
*/
|
|
UDate getMoonTime(double desired, UBool next);
|
|
UDate getMoonTime(const MoonAge& desired, UBool next);
|
|
|
|
/**
|
|
* Returns the time (GMT) of sunrise or sunset on the local date to which
|
|
* this calendar is currently set.
|
|
* @internal
|
|
*/
|
|
UDate getMoonRiseSet(UBool rise);
|
|
|
|
//-------------------------------------------------------------------------
|
|
// Interpolation methods for finding the time at which a given event occurs
|
|
//-------------------------------------------------------------------------
|
|
|
|
// private
|
|
class U_I18N_API AngleFunc : public UMemory {
|
|
public:
|
|
virtual double eval(CalendarAstronomer&) = 0;
|
|
};
|
|
friend class AngleFunc;
|
|
|
|
UDate timeOfAngle(AngleFunc& func, double desired,
|
|
double periodDays, double epsilon, UBool next);
|
|
|
|
class U_I18N_API CoordFunc : public UMemory {
|
|
public:
|
|
virtual void eval(Equatorial& result, CalendarAstronomer&) = 0;
|
|
};
|
|
friend class CoordFunc;
|
|
|
|
double riseOrSet(CoordFunc& func, UBool rise,
|
|
double diameter, double refraction,
|
|
double epsilon);
|
|
|
|
//-------------------------------------------------------------------------
|
|
// Other utility methods
|
|
//-------------------------------------------------------------------------
|
|
private:
|
|
/***
|
|
* Given 'value', add or subtract 'range' until 0 <= 'value' < range.
|
|
* The modulus operator.
|
|
*/
|
|
inline static double normalize(double value, double range) {
|
|
return value - range * Math::floorDivide(value, range);
|
|
}
|
|
|
|
/**
|
|
* Normalize an angle so that it's in the range 0 - 2pi.
|
|
* For positive angles this is just (angle % 2pi), but the Java
|
|
* mod operator doesn't work that way for negative numbers....
|
|
*/
|
|
inline static double norm2PI(double angle) {
|
|
return normalize(angle, CalendarAstronomer::PI * 2.0);
|
|
}
|
|
|
|
/**
|
|
* Normalize an angle into the range -PI - PI
|
|
*/
|
|
inline static double normPI(double angle) {
|
|
return normalize(angle + PI, CalendarAstronomer::PI * 2.0) - PI;
|
|
}
|
|
|
|
/**
|
|
* Find the "true anomaly" (longitude) of an object from
|
|
* its mean anomaly and the eccentricity of its orbit. This uses
|
|
* an iterative solution to Kepler's equation.
|
|
*
|
|
* @param meanAnomaly The object's longitude calculated as if it were in
|
|
* a regular, circular orbit, measured in radians
|
|
* from the point of perigee.
|
|
*
|
|
* @param eccentricity The eccentricity of the orbit
|
|
*
|
|
* @return The true anomaly (longitude) measured in radians
|
|
*/
|
|
double trueAnomaly(double meanAnomaly, double eccentricity);
|
|
|
|
/**
|
|
* Return the obliquity of the ecliptic (the angle between the ecliptic
|
|
* and the earth's equator) at the current time. This varies due to
|
|
* the precession of the earth's axis.
|
|
*
|
|
* @return the obliquity of the ecliptic relative to the equator,
|
|
* measured in radians.
|
|
*/
|
|
double eclipticObliquity();
|
|
|
|
//-------------------------------------------------------------------------
|
|
// Private data
|
|
//-------------------------------------------------------------------------
|
|
private:
|
|
/**
|
|
* Current time in milliseconds since 1/1/1970 AD
|
|
* @see java.util.Date#getTime
|
|
*/
|
|
UDate fTime;
|
|
|
|
/* These aren't used yet, but they'll be needed for sunset calculations
|
|
* and equatorial to horizon coordinate conversions
|
|
*/
|
|
double fLongitude;
|
|
double fLatitude;
|
|
double fGmtOffset;
|
|
|
|
//
|
|
// The following fields are used to cache calculated results for improved
|
|
// performance. These values all depend on the current time setting
|
|
// of this object, so the clearCache method is provided.
|
|
//
|
|
|
|
double julianDay ;
|
|
double julianCentury ;
|
|
double sunLongitude ;
|
|
double meanAnomalySun ;
|
|
double moonLongitude ;
|
|
double moonEclipLong ;
|
|
double meanAnomalyMoon ;
|
|
double eclipObliquity ;
|
|
double siderealT0 ;
|
|
double siderealTime ;
|
|
|
|
void clearCache();
|
|
|
|
Equatorial moonPosition;
|
|
UBool moonPositionSet;
|
|
|
|
/**
|
|
* @internal
|
|
*/
|
|
UDate local(UDate localMillis);
|
|
};
|
|
#endif
|
|
#endif
|