Check in the pristine copy of ICU 4.6...

icu46/source/i18n/astro.h

+/************************************************************************
+ * 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