current/deps/icu-small/source/i18n/astro.h
// © 2016 and later: Unicode, Inc. and others.
// License & terms of use: http://www.unicode.org/copyright.html
/************************************************************************
* Copyright (C) 1996-2008, International Business Machines Corporation *
* and others. All Rights Reserved. *
************************************************************************
* 2003-nov-07 srl Port from Java
*/
#ifndef ASTRO_H
#define ASTRO_H
#include "unicode/utypes.h"
#if !UCONFIG_NO_FORMATTING
#include "gregoimp.h" // for Math
#include "unicode/unistr.h"
U_NAMESPACE_BEGIN
/**
* <code>CalendarAstronomer</code> is a class that can perform the calculations to
* determine the positions of the sun and moon, the time of sunrise and
* sunset, and other astronomy-related data. The calculations it performs
* are in some cases quite complicated, and this utility class saves you
* the trouble of worrying about them.
* <p>
* The measurement of time is a very important part of astronomy. Because
* astronomical bodies are constantly in motion, observations are only valid
* at a given moment in time. Accordingly, each <code>CalendarAstronomer</code>
* object has a <code>time</code> property that determines the date
* and time for which its calculations are performed. You can set and
* retrieve this property with {@link #setDate setDate}, {@link #getDate getDate}
* and related methods.
* <p>
* Almost all of the calculations performed by this class, or by any
* astronomer, are approximations to various degrees of accuracy. The
* calculations in this class are mostly modelled after those described
* in the book
* <a href="http://www.amazon.com/exec/obidos/ISBN=0521356997" target="_top">
* Practical Astronomy With Your Calculator</a>, by Peter J.
* Duffett-Smith, Cambridge University Press, 1990. This is an excellent
* book, and if you want a greater understanding of how these calculations
* are performed it a very good, readable starting point.
* <p>
* <strong>WARNING:</strong> This class is very early in its development, and
* it is highly likely that its API will change to some degree in the future.
* At the moment, it basically does just enough to support {@link IslamicCalendar}
* and {@link ChineseCalendar}.
*
* @author Laura Werner
* @author Alan Liu
* @internal
*/
class U_I18N_API CalendarAstronomer : public UMemory {
public:
// some classes
public:
/**
* Represents the position of an object in the sky relative to the ecliptic,
* the plane of the earth's orbit around the Sun.
* This is a spherical coordinate system in which the latitude
* specifies the position north or south of the plane of the ecliptic.
* The longitude specifies the position along the ecliptic plane
* relative to the "First Point of Aries", which is the Sun's position in the sky
* at the Vernal Equinox.
* <p>
* Note that Ecliptic objects are immutable and cannot be modified
* once they are constructed. This allows them to be passed and returned by
* value without worrying about whether other code will modify them.
*
* @see CalendarAstronomer.Equatorial
* @see CalendarAstronomer.Horizon
* @internal
*/
class U_I18N_API Ecliptic : public UMemory {
public:
/**
* Constructs an Ecliptic coordinate object.
* <p>
* @param lat The ecliptic latitude, measured in radians.
* @param lon The ecliptic longitude, measured in radians.
* @internal
*/
Ecliptic(double lat = 0, double lon = 0) {
latitude = lat;
longitude = lon;
}
/**
* Setter for Ecliptic Coordinate object
* @param lat The ecliptic latitude, measured in radians.
* @param lon The ecliptic longitude, measured in radians.
* @internal
*/
void set(double lat, double lon) {
latitude = lat;
longitude = lon;
}
/**
* Return a string representation of this object
* @internal
*/
UnicodeString toString() const;
/**
* The ecliptic latitude, in radians. This specifies an object's
* position north or south of the plane of the ecliptic,
* with positive angles representing north.
* @internal
*/
double latitude;
/**
* The ecliptic longitude, in radians.
* This specifies an object's position along the ecliptic plane
* relative to the "First Point of Aries", which is the Sun's position
* in the sky at the Vernal Equinox,
* with positive angles representing east.
* <p>
* A bit of trivia: the first point of Aries is currently in the
* constellation Pisces, due to the precession of the earth's axis.
* @internal
*/
double longitude;
};
/**
* Represents the position of an
* object in the sky relative to the plane of the earth's equator.
* The <i>Right Ascension</i> specifies the position east or west
* along the equator, relative to the sun's position at the vernal
* equinox. The <i>Declination</i> is the position north or south
* of the equatorial plane.
* <p>
* Note that Equatorial objects are immutable and cannot be modified
* once they are constructed. This allows them to be passed and returned by
* value without worrying about whether other code will modify them.
*
* @see CalendarAstronomer.Ecliptic
* @see CalendarAstronomer.Horizon
* @internal
*/
class U_I18N_API Equatorial : public UMemory {
public:
/**
* Constructs an Equatorial coordinate object.
* <p>
* @param asc The right ascension, measured in radians.
* @param dec The declination, measured in radians.
* @internal
*/
Equatorial(double asc = 0, double dec = 0)
: ascension(asc), declination(dec) { }
/**
* Setter
* @param asc The right ascension, measured in radians.
* @param dec The declination, measured in radians.
* @internal
*/
void set(double asc, double dec) {
ascension = asc;
declination = dec;
}
/**
* Return a string representation of this object, with the
* angles measured in degrees.
* @internal
*/
UnicodeString toString() const;
/**
* Return a string representation of this object with the right ascension
* measured in hours, minutes, and seconds.
* @internal
*/
//String toHmsString() {
//return radToHms(ascension) + "," + radToDms(declination);
//}
/**
* The right ascension, in radians.
* This is the position east or west along the equator
* relative to the sun's position at the vernal equinox,
* with positive angles representing East.
* @internal
*/
double ascension;
/**
* The declination, in radians.
* This is the position north or south of the equatorial plane,
* with positive angles representing north.
* @internal
*/
double declination;
};
/**
* Represents the position of an object in the sky relative to
* the local horizon.
* The <i>Altitude</i> represents the object's elevation above the horizon,
* with objects below the horizon having a negative altitude.
* The <i>Azimuth</i> is the geographic direction of the object from the
* observer's position, with 0 representing north. The azimuth increases
* clockwise from north.
* <p>
* Note that Horizon objects are immutable and cannot be modified
* once they are constructed. This allows them to be passed and returned by
* value without worrying about whether other code will modify them.
*
* @see CalendarAstronomer.Ecliptic
* @see CalendarAstronomer.Equatorial
* @internal
*/
class U_I18N_API Horizon : public UMemory {
public:
/**
* Constructs a Horizon coordinate object.
* <p>
* @param alt The altitude, measured in radians above the horizon.
* @param azim The azimuth, measured in radians clockwise from north.
* @internal
*/
Horizon(double alt=0, double azim=0)
: altitude(alt), azimuth(azim) { }
/**
* Setter for Ecliptic Coordinate object
* @param alt The altitude, measured in radians above the horizon.
* @param azim The azimuth, measured in radians clockwise from north.
* @internal
*/
void set(double alt, double azim) {
altitude = alt;
azimuth = azim;
}
/**
* Return a string representation of this object, with the
* angles measured in degrees.
* @internal
*/
UnicodeString toString() const;
/**
* The object's altitude above the horizon, in radians.
* @internal
*/
double altitude;
/**
* The object's direction, in radians clockwise from north.
* @internal
*/
double azimuth;
};
public:
//-------------------------------------------------------------------------
// Assorted private data used for conversions
//-------------------------------------------------------------------------
// My own copies of these so compilers are more likely to optimize them away
static const double PI;
/**
* The average number of solar days from one new moon to the next. This is the time
* it takes for the moon to return the same ecliptic longitude as the sun.
* It is longer than the sidereal month because the sun's longitude increases
* during the year due to the revolution of the earth around the sun.
* Approximately 29.53.
*
* @see #SIDEREAL_MONTH
* @internal
* @deprecated ICU 2.4. This class may be removed or modified.
*/
static const double SYNODIC_MONTH;
//-------------------------------------------------------------------------
// Constructors
//-------------------------------------------------------------------------
/**
* Construct a new <code>CalendarAstronomer</code> object that is initialized to
* the current date and time.
* @internal
*/
CalendarAstronomer();
/**
* Construct a new <code>CalendarAstronomer</code> object that is initialized to
* the specified date and time.
* @internal
*/
CalendarAstronomer(UDate d);
/**
* Construct a new <code>CalendarAstronomer</code> object with the given
* latitude and longitude. The object's time is set to the current
* date and time.
* <p>
* @param longitude The desired longitude, in <em>degrees</em> east of
* the Greenwich meridian.
*
* @param latitude The desired latitude, in <em>degrees</em>. Positive
* values signify North, negative South.
*
* @see java.util.Date#getTime()
* @internal
*/
CalendarAstronomer(double longitude, double latitude);
/**
* Destructor
* @internal
*/
~CalendarAstronomer();
//-------------------------------------------------------------------------
// Time and date getters and setters
//-------------------------------------------------------------------------
/**
* Set the current date and time of this <code>CalendarAstronomer</code> object. All
* astronomical calculations are performed based on this time setting.
*
* @param aTime the date and time, expressed as the number of milliseconds since
* 1/1/1970 0:00 GMT (Gregorian).
*
* @see #setDate
* @see #getTime
* @internal
*/
void setTime(UDate aTime);
/**
* Set the current date and time of this <code>CalendarAstronomer</code> object. All
* astronomical calculations are performed based on this time setting.
*
* @param aTime the date and time, expressed as the number of milliseconds since
* 1/1/1970 0:00 GMT (Gregorian).
*
* @see #getTime
* @internal
*/
void setDate(UDate aDate) { setTime(aDate); }
/**
* Set the current date and time of this <code>CalendarAstronomer</code> object. All
* astronomical calculations are performed based on this time setting.
*
* @param jdn the desired time, expressed as a "julian day number",
* which is the number of elapsed days since
* 1/1/4713 BC (Julian), 12:00 GMT. Note that julian day
* numbers start at <em>noon</em>. To get the jdn for
* the corresponding midnight, subtract 0.5.
*
* @see #getJulianDay
* @see #JULIAN_EPOCH_MS
* @internal
*/
void setJulianDay(double jdn);
/**
* Get the current time of this <code>CalendarAstronomer</code> object,
* represented as the number of milliseconds since
* 1/1/1970 AD 0:00 GMT (Gregorian).
*
* @see #setTime
* @see #getDate
* @internal
*/
UDate getTime();
/**
* Get the current time of this <code>CalendarAstronomer</code> object,
* expressed as a "julian day number", which is the number of elapsed
* days since 1/1/4713 BC (Julian), 12:00 GMT.
*
* @see #setJulianDay
* @see #JULIAN_EPOCH_MS
* @internal
*/
double getJulianDay();
/**
* Return this object's time expressed in julian centuries:
* the number of centuries after 1/1/1900 AD, 12:00 GMT
*
* @see #getJulianDay
* @internal
*/
double getJulianCentury();
/**
* Returns the current Greenwich sidereal time, measured in hours
* @internal
*/
double getGreenwichSidereal();
private:
double getSiderealOffset();
public:
/**
* Returns the current local sidereal time, measured in hours
* @internal
*/
double getLocalSidereal();
/**
* Converts local sidereal time to Universal Time.
*
* @param lst The Local Sidereal Time, in hours since sidereal midnight
* on this object's current date.
*
* @return The corresponding Universal Time, in milliseconds since
* 1 Jan 1970, GMT.
*/
//private:
double lstToUT(double lst);
/**
*
* Convert from ecliptic to equatorial coordinates.
*
* @param ecliptic The ecliptic
* @param result Fillin result
* @return reference to result
*/
Equatorial& eclipticToEquatorial(Equatorial& result, const Ecliptic& ecliptic);
/**
* Convert from ecliptic to equatorial coordinates.
*
* @param eclipLong The ecliptic longitude
* @param eclipLat The ecliptic latitude
*
* @return The corresponding point in equatorial coordinates.
* @internal
*/
Equatorial& eclipticToEquatorial(Equatorial& result, double eclipLong, double eclipLat);
/**
* Convert from ecliptic longitude to equatorial coordinates.
*
* @param eclipLong The ecliptic longitude
*
* @return The corresponding point in equatorial coordinates.
* @internal
*/
Equatorial& eclipticToEquatorial(Equatorial& result, double eclipLong) ;
/**
* @internal
*/
Horizon& eclipticToHorizon(Horizon& result, double eclipLong) ;
//-------------------------------------------------------------------------
// The Sun
//-------------------------------------------------------------------------
/**
* The longitude of the sun at the time specified by this object.
* The longitude is measured in radians along the ecliptic
* from the "first point of Aries," the point at which the ecliptic
* crosses the earth's equatorial plane at the vernal equinox.
* <p>
* Currently, this method uses an approximation of the two-body Kepler's
* equation for the earth and the sun. It does not take into account the
* perturbations caused by the other planets, the moon, etc.
* @internal
*/
double getSunLongitude();
/**
* TODO Make this public when the entire class is package-private.
*/
/*public*/ void getSunLongitude(double julianDay, double &longitude, double &meanAnomaly);
/**
* The position of the sun at this object's current date and time,
* in equatorial coordinates.
* @param result fillin for the result
* @internal
*/
Equatorial& getSunPosition(Equatorial& result);
public:
/**
* Constant representing the vernal equinox.
* For use with {@link #getSunTime getSunTime}.
* Note: In this case, "vernal" refers to the northern hemisphere's seasons.
* @internal
*/
// static double VERNAL_EQUINOX();
/**
* Constant representing the summer solstice.
* For use with {@link #getSunTime getSunTime}.
* Note: In this case, "summer" refers to the northern hemisphere's seasons.
* @internal
*/
static double SUMMER_SOLSTICE();
/**
* Constant representing the autumnal equinox.
* For use with {@link #getSunTime getSunTime}.
* Note: In this case, "autumn" refers to the northern hemisphere's seasons.
* @internal
*/
// static double AUTUMN_EQUINOX();
/**
* Constant representing the winter solstice.
* For use with {@link #getSunTime getSunTime}.
* Note: In this case, "winter" refers to the northern hemisphere's seasons.
* @internal
*/
static double WINTER_SOLSTICE();
/**
* Find the next time at which the sun's ecliptic longitude will have
* the desired value.
* @internal
*/
UDate getSunTime(double desired, UBool next);
/**
* Returns the time (GMT) of sunrise or sunset on the local date to which
* this calendar is currently set.
*
* NOTE: This method only works well if this object is set to a
* time near local noon. Because of variations between the local
* official time zone and the geographic longitude, the
* computation can flop over into an adjacent day if this object
* is set to a time near local midnight.
*
* @internal
*/
UDate getSunRiseSet(UBool rise);
//-------------------------------------------------------------------------
// The Moon
//-------------------------------------------------------------------------
/**
* The position of the moon at the time set on this
* object, in equatorial coordinates.
* @internal
* @return const reference to internal field of calendar astronomer. Do not use outside of the lifetime of this astronomer.
*/
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 AngleFunc : public UMemory {
public:
virtual double eval(CalendarAstronomer&) = 0;
virtual ~AngleFunc();
};
friend class AngleFunc;
UDate timeOfAngle(AngleFunc& func, double desired,
double periodDays, double epsilon, UBool next);
class CoordFunc : public UMemory {
public:
virtual void eval(Equatorial& result, CalendarAstronomer&) = 0;
virtual ~CoordFunc();
};
friend class CoordFunc;
double riseOrSet(CoordFunc& func, UBool rise,
double diameter, double refraction,
double epsilon);
//-------------------------------------------------------------------------
// Other utility methods
//-------------------------------------------------------------------------
private:
/**
* 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);
};
U_NAMESPACE_END
struct UHashtable;
U_NAMESPACE_BEGIN
/**
* Cache of month -> julian day
* @internal
*/
class CalendarCache : public UMemory {
public:
static int32_t get(CalendarCache** cache, int32_t key, UErrorCode &status);
static void put(CalendarCache** cache, int32_t key, int32_t value, UErrorCode &status);
virtual ~CalendarCache();
private:
CalendarCache(int32_t size, UErrorCode& status);
static void createCache(CalendarCache** cache, UErrorCode& status);
/**
* not implemented
*/
CalendarCache();
UHashtable *fTable;
};
U_NAMESPACE_END
#endif
#endif