1 /************************************************************************
2 * Copyright (C) 1996-2007, International Business Machines Corporation *
3 * and others. All Rights Reserved. *
4 ************************************************************************
5 * 2003-nov-07 srl Port from Java
6 */
7
8 #include "astro.h"
9
10 #if !UCONFIG_NO_FORMATTING
11
12 #include "unicode/calendar.h"
13 #include <math.h>
14 #include <float.h>
15 #include "unicode/putil.h"
16 #include "uhash.h"
17 #include "umutex.h"
18 #include "ucln_in.h"
19 #include "putilimp.h"
20 #include <stdio.h> // for toString()
21
22 #ifdef U_DEBUG_ASTRO
23 # include "uresimp.h" // for debugging
24
debug_astro_loc(const char * f,int32_t l)25 static void debug_astro_loc(const char *f, int32_t l)
26 {
27 fprintf(stderr, "%s:%d: ", f, l);
28 }
29
debug_astro_msg(const char * pat,...)30 static void debug_astro_msg(const char *pat, ...)
31 {
32 va_list ap;
33 va_start(ap, pat);
34 vfprintf(stderr, pat, ap);
35 fflush(stderr);
36 }
37 #include "unicode/datefmt.h"
38 #include "unicode/ustring.h"
debug_astro_date(UDate d)39 static const char * debug_astro_date(UDate d) {
40 static char gStrBuf[1024];
41 static DateFormat *df = NULL;
42 if(df == NULL) {
43 df = DateFormat::createDateTimeInstance(DateFormat::MEDIUM, DateFormat::MEDIUM, Locale::getUS());
44 df->adoptTimeZone(TimeZone::getGMT()->clone());
45 }
46 UnicodeString str;
47 df->format(d,str);
48 u_austrncpy(gStrBuf,str.getTerminatedBuffer(),sizeof(gStrBuf)-1);
49 return gStrBuf;
50 }
51
52 // must use double parens, i.e.: U_DEBUG_ASTRO_MSG(("four is: %d",4));
53 #define U_DEBUG_ASTRO_MSG(x) {debug_astro_loc(__FILE__,__LINE__);debug_astro_msg x;}
54 #else
55 #define U_DEBUG_ASTRO_MSG(x)
56 #endif
57
isINVALID(double d)58 static inline UBool isINVALID(double d) {
59 return(uprv_isNaN(d));
60 }
61
62 static UMTX ccLock = NULL;
63
64 U_CDECL_BEGIN
calendar_astro_cleanup(void)65 static UBool calendar_astro_cleanup(void) {
66 umtx_destroy(&ccLock);
67 return TRUE;
68 }
69 U_CDECL_END
70
71 U_NAMESPACE_BEGIN
72
73 /**
74 * The number of standard hours in one sidereal day.
75 * Approximately 24.93.
76 * @internal
77 * @deprecated ICU 2.4. This class may be removed or modified.
78 */
79 #define SIDEREAL_DAY (23.93446960027)
80
81 /**
82 * The number of sidereal hours in one mean solar day.
83 * Approximately 24.07.
84 * @internal
85 * @deprecated ICU 2.4. This class may be removed or modified.
86 */
87 #define SOLAR_DAY (24.065709816)
88
89 /**
90 * The average number of solar days from one new moon to the next. This is the time
91 * it takes for the moon to return the same ecliptic longitude as the sun.
92 * It is longer than the sidereal month because the sun's longitude increases
93 * during the year due to the revolution of the earth around the sun.
94 * Approximately 29.53.
95 *
96 * @see #SIDEREAL_MONTH
97 * @internal
98 * @deprecated ICU 2.4. This class may be removed or modified.
99 */
100 const double CalendarAstronomer::SYNODIC_MONTH = 29.530588853;
101
102 /**
103 * The average number of days it takes
104 * for the moon to return to the same ecliptic longitude relative to the
105 * stellar background. This is referred to as the sidereal month.
106 * It is shorter than the synodic month due to
107 * the revolution of the earth around the sun.
108 * Approximately 27.32.
109 *
110 * @see #SYNODIC_MONTH
111 * @internal
112 * @deprecated ICU 2.4. This class may be removed or modified.
113 */
114 #define SIDEREAL_MONTH 27.32166
115
116 /**
117 * The average number number of days between successive vernal equinoxes.
118 * Due to the precession of the earth's
119 * axis, this is not precisely the same as the sidereal year.
120 * Approximately 365.24
121 *
122 * @see #SIDEREAL_YEAR
123 * @internal
124 * @deprecated ICU 2.4. This class may be removed or modified.
125 */
126 #define TROPICAL_YEAR 365.242191
127
128 /**
129 * The average number of days it takes
130 * for the sun to return to the same position against the fixed stellar
131 * background. This is the duration of one orbit of the earth about the sun
132 * as it would appear to an outside observer.
133 * Due to the precession of the earth's
134 * axis, this is not precisely the same as the tropical year.
135 * Approximately 365.25.
136 *
137 * @see #TROPICAL_YEAR
138 * @internal
139 * @deprecated ICU 2.4. This class may be removed or modified.
140 */
141 #define SIDEREAL_YEAR 365.25636
142
143 //-------------------------------------------------------------------------
144 // Time-related constants
145 //-------------------------------------------------------------------------
146
147 /**
148 * The number of milliseconds in one second.
149 * @internal
150 * @deprecated ICU 2.4. This class may be removed or modified.
151 */
152 #define SECOND_MS U_MILLIS_PER_SECOND
153
154 /**
155 * The number of milliseconds in one minute.
156 * @internal
157 * @deprecated ICU 2.4. This class may be removed or modified.
158 */
159 #define MINUTE_MS U_MILLIS_PER_MINUTE
160
161 /**
162 * The number of milliseconds in one hour.
163 * @internal
164 * @deprecated ICU 2.4. This class may be removed or modified.
165 */
166 #define HOUR_MS U_MILLIS_PER_HOUR
167
168 /**
169 * The number of milliseconds in one day.
170 * @internal
171 * @deprecated ICU 2.4. This class may be removed or modified.
172 */
173 #define DAY_MS U_MILLIS_PER_DAY
174
175 /**
176 * The start of the julian day numbering scheme used by astronomers, which
177 * is 1/1/4713 BC (Julian), 12:00 GMT. This is given as the number of milliseconds
178 * since 1/1/1970 AD (Gregorian), a negative number.
179 * Note that julian day numbers and
180 * the Julian calendar are <em>not</em> the same thing. Also note that
181 * julian days start at <em>noon</em>, not midnight.
182 * @internal
183 * @deprecated ICU 2.4. This class may be removed or modified.
184 */
185 #define JULIAN_EPOCH_MS -210866760000000.0
186
187
188 /**
189 * Milliseconds value for 0.0 January 2000 AD.
190 */
191 #define EPOCH_2000_MS 946598400000.0
192
193 //-------------------------------------------------------------------------
194 // Assorted private data used for conversions
195 //-------------------------------------------------------------------------
196
197 // My own copies of these so compilers are more likely to optimize them away
198 const double CalendarAstronomer::PI = 3.14159265358979323846;
199
200 #define CalendarAstronomer_PI2 (CalendarAstronomer::PI*2.0)
201 #define RAD_HOUR ( 12 / CalendarAstronomer::PI ) // radians -> hours
202 #define DEG_RAD ( CalendarAstronomer::PI / 180 ) // degrees -> radians
203 #define RAD_DEG ( 180 / CalendarAstronomer::PI ) // radians -> degrees
204
205 //-------------------------------------------------------------------------
206 // Constructors
207 //-------------------------------------------------------------------------
208
209 /**
210 * Construct a new <code>CalendarAstronomer</code> object that is initialized to
211 * the current date and time.
212 * @internal
213 * @deprecated ICU 2.4. This class may be removed or modified.
214 */
CalendarAstronomer()215 CalendarAstronomer::CalendarAstronomer():
216 fTime(Calendar::getNow()), fLongitude(0.0), fLatitude(0.0), fGmtOffset(0.0), moonPosition(0,0), moonPositionSet(FALSE) {
217 clearCache();
218 }
219
220 /**
221 * Construct a new <code>CalendarAstronomer</code> object that is initialized to
222 * the specified date and time.
223 * @internal
224 * @deprecated ICU 2.4. This class may be removed or modified.
225 */
CalendarAstronomer(UDate d)226 CalendarAstronomer::CalendarAstronomer(UDate d): fTime(d), fLongitude(0.0), fLatitude(0.0), fGmtOffset(0.0), moonPosition(0,0), moonPositionSet(FALSE) {
227 clearCache();
228 }
229
230 /**
231 * Construct a new <code>CalendarAstronomer</code> object with the given
232 * latitude and longitude. The object's time is set to the current
233 * date and time.
234 * <p>
235 * @param longitude The desired longitude, in <em>degrees</em> east of
236 * the Greenwich meridian.
237 *
238 * @param latitude The desired latitude, in <em>degrees</em>. Positive
239 * values signify North, negative South.
240 *
241 * @see java.util.Date#getTime()
242 * @internal
243 * @deprecated ICU 2.4. This class may be removed or modified.
244 */
CalendarAstronomer(double longitude,double latitude)245 CalendarAstronomer::CalendarAstronomer(double longitude, double latitude) :
246 fTime(Calendar::getNow()), moonPosition(0,0), moonPositionSet(FALSE) {
247 fLongitude = normPI(longitude * (double)DEG_RAD);
248 fLatitude = normPI(latitude * (double)DEG_RAD);
249 fGmtOffset = (double)(fLongitude * 24. * (double)HOUR_MS / (double)CalendarAstronomer_PI2);
250 clearCache();
251 }
252
~CalendarAstronomer()253 CalendarAstronomer::~CalendarAstronomer()
254 {
255 }
256
257 //-------------------------------------------------------------------------
258 // Time and date getters and setters
259 //-------------------------------------------------------------------------
260
261 /**
262 * Set the current date and time of this <code>CalendarAstronomer</code> object. All
263 * astronomical calculations are performed based on this time setting.
264 *
265 * @param aTime the date and time, expressed as the number of milliseconds since
266 * 1/1/1970 0:00 GMT (Gregorian).
267 *
268 * @see #setDate
269 * @see #getTime
270 * @internal
271 * @deprecated ICU 2.4. This class may be removed or modified.
272 */
setTime(UDate aTime)273 void CalendarAstronomer::setTime(UDate aTime) {
274 fTime = aTime;
275 U_DEBUG_ASTRO_MSG(("setTime(%.1lf, %sL)\n", aTime, debug_astro_date(aTime+fGmtOffset)));
276 clearCache();
277 }
278
279 /**
280 * Set the current date and time of this <code>CalendarAstronomer</code> object. All
281 * astronomical calculations are performed based on this time setting.
282 *
283 * @param jdn the desired time, expressed as a "julian day number",
284 * which is the number of elapsed days since
285 * 1/1/4713 BC (Julian), 12:00 GMT. Note that julian day
286 * numbers start at <em>noon</em>. To get the jdn for
287 * the corresponding midnight, subtract 0.5.
288 *
289 * @see #getJulianDay
290 * @see #JULIAN_EPOCH_MS
291 * @internal
292 * @deprecated ICU 2.4. This class may be removed or modified.
293 */
setJulianDay(double jdn)294 void CalendarAstronomer::setJulianDay(double jdn) {
295 fTime = (double)(jdn * DAY_MS) + JULIAN_EPOCH_MS;
296 clearCache();
297 julianDay = jdn;
298 }
299
300 /**
301 * Get the current time of this <code>CalendarAstronomer</code> object,
302 * represented as the number of milliseconds since
303 * 1/1/1970 AD 0:00 GMT (Gregorian).
304 *
305 * @see #setTime
306 * @see #getDate
307 * @internal
308 * @deprecated ICU 2.4. This class may be removed or modified.
309 */
getTime()310 UDate CalendarAstronomer::getTime() {
311 return fTime;
312 }
313
314 /**
315 * Get the current time of this <code>CalendarAstronomer</code> object,
316 * expressed as a "julian day number", which is the number of elapsed
317 * days since 1/1/4713 BC (Julian), 12:00 GMT.
318 *
319 * @see #setJulianDay
320 * @see #JULIAN_EPOCH_MS
321 * @internal
322 * @deprecated ICU 2.4. This class may be removed or modified.
323 */
getJulianDay()324 double CalendarAstronomer::getJulianDay() {
325 if (isINVALID(julianDay)) {
326 julianDay = (fTime - (double)JULIAN_EPOCH_MS) / (double)DAY_MS;
327 }
328 return julianDay;
329 }
330
331 /**
332 * Return this object's time expressed in julian centuries:
333 * the number of centuries after 1/1/1900 AD, 12:00 GMT
334 *
335 * @see #getJulianDay
336 * @internal
337 * @deprecated ICU 2.4. This class may be removed or modified.
338 */
getJulianCentury()339 double CalendarAstronomer::getJulianCentury() {
340 if (isINVALID(julianCentury)) {
341 julianCentury = (getJulianDay() - 2415020.0) / 36525.0;
342 }
343 return julianCentury;
344 }
345
346 /**
347 * Returns the current Greenwich sidereal time, measured in hours
348 * @internal
349 * @deprecated ICU 2.4. This class may be removed or modified.
350 */
getGreenwichSidereal()351 double CalendarAstronomer::getGreenwichSidereal() {
352 if (isINVALID(siderealTime)) {
353 // See page 86 of "Practial Astronomy with your Calculator",
354 // by Peter Duffet-Smith, for details on the algorithm.
355
356 double UT = normalize(fTime/(double)HOUR_MS, 24.);
357
358 siderealTime = normalize(getSiderealOffset() + UT*1.002737909, 24.);
359 }
360 return siderealTime;
361 }
362
getSiderealOffset()363 double CalendarAstronomer::getSiderealOffset() {
364 if (isINVALID(siderealT0)) {
365 double JD = uprv_floor(getJulianDay() - 0.5) + 0.5;
366 double S = JD - 2451545.0;
367 double T = S / 36525.0;
368 siderealT0 = normalize(6.697374558 + 2400.051336*T + 0.000025862*T*T, 24);
369 }
370 return siderealT0;
371 }
372
373 /**
374 * Returns the current local sidereal time, measured in hours
375 * @internal
376 * @deprecated ICU 2.4. This class may be removed or modified.
377 */
getLocalSidereal()378 double CalendarAstronomer::getLocalSidereal() {
379 return normalize(getGreenwichSidereal() + (fGmtOffset/(double)HOUR_MS), 24.);
380 }
381
382 /**
383 * Converts local sidereal time to Universal Time.
384 *
385 * @param lst The Local Sidereal Time, in hours since sidereal midnight
386 * on this object's current date.
387 *
388 * @return The corresponding Universal Time, in milliseconds since
389 * 1 Jan 1970, GMT.
390 */
lstToUT(double lst)391 double CalendarAstronomer::lstToUT(double lst) {
392 // Convert to local mean time
393 double lt = normalize((lst - getSiderealOffset()) * 0.9972695663, 24);
394
395 // Then find local midnight on this day
396 double base = (DAY_MS * Math::floorDivide(fTime + fGmtOffset,(double)DAY_MS)) - fGmtOffset;
397
398 //out(" lt =" + lt + " hours");
399 //out(" base=" + new Date(base));
400
401 return base + (long)(lt * HOUR_MS);
402 }
403
404
405 //-------------------------------------------------------------------------
406 // Coordinate transformations, all based on the current time of this object
407 //-------------------------------------------------------------------------
408
409 /**
410 * Convert from ecliptic to equatorial coordinates.
411 *
412 * @param ecliptic A point in the sky in ecliptic coordinates.
413 * @return The corresponding point in equatorial coordinates.
414 * @internal
415 * @deprecated ICU 2.4. This class may be removed or modified.
416 */
eclipticToEquatorial(CalendarAstronomer::Equatorial & result,const CalendarAstronomer::Ecliptic & ecliptic)417 CalendarAstronomer::Equatorial& CalendarAstronomer::eclipticToEquatorial(CalendarAstronomer::Equatorial& result, const CalendarAstronomer::Ecliptic& ecliptic)
418 {
419 return eclipticToEquatorial(result, ecliptic.longitude, ecliptic.latitude);
420 }
421
422 /**
423 * Convert from ecliptic to equatorial coordinates.
424 *
425 * @param eclipLong The ecliptic longitude
426 * @param eclipLat The ecliptic latitude
427 *
428 * @return The corresponding point in equatorial coordinates.
429 * @internal
430 * @deprecated ICU 2.4. This class may be removed or modified.
431 */
eclipticToEquatorial(CalendarAstronomer::Equatorial & result,double eclipLong,double eclipLat)432 CalendarAstronomer::Equatorial& CalendarAstronomer::eclipticToEquatorial(CalendarAstronomer::Equatorial& result, double eclipLong, double eclipLat)
433 {
434 // See page 42 of "Practial Astronomy with your Calculator",
435 // by Peter Duffet-Smith, for details on the algorithm.
436
437 double obliq = eclipticObliquity();
438 double sinE = ::sin(obliq);
439 double cosE = cos(obliq);
440
441 double sinL = ::sin(eclipLong);
442 double cosL = cos(eclipLong);
443
444 double sinB = ::sin(eclipLat);
445 double cosB = cos(eclipLat);
446 double tanB = tan(eclipLat);
447
448 result.set(atan2(sinL*cosE - tanB*sinE, cosL),
449 asin(sinB*cosE + cosB*sinE*sinL) );
450 return result;
451 }
452
453 /**
454 * Convert from ecliptic longitude to equatorial coordinates.
455 *
456 * @param eclipLong The ecliptic longitude
457 *
458 * @return The corresponding point in equatorial coordinates.
459 * @internal
460 * @deprecated ICU 2.4. This class may be removed or modified.
461 */
eclipticToEquatorial(CalendarAstronomer::Equatorial & result,double eclipLong)462 CalendarAstronomer::Equatorial& CalendarAstronomer::eclipticToEquatorial(CalendarAstronomer::Equatorial& result, double eclipLong)
463 {
464 return eclipticToEquatorial(result, eclipLong, 0); // TODO: optimize
465 }
466
467 /**
468 * @internal
469 * @deprecated ICU 2.4. This class may be removed or modified.
470 */
eclipticToHorizon(CalendarAstronomer::Horizon & result,double eclipLong)471 CalendarAstronomer::Horizon& CalendarAstronomer::eclipticToHorizon(CalendarAstronomer::Horizon& result, double eclipLong)
472 {
473 Equatorial equatorial;
474 eclipticToEquatorial(equatorial, eclipLong);
475
476 double H = getLocalSidereal()*CalendarAstronomer::PI/12 - equatorial.ascension; // Hour-angle
477
478 double sinH = ::sin(H);
479 double cosH = cos(H);
480 double sinD = ::sin(equatorial.declination);
481 double cosD = cos(equatorial.declination);
482 double sinL = ::sin(fLatitude);
483 double cosL = cos(fLatitude);
484
485 double altitude = asin(sinD*sinL + cosD*cosL*cosH);
486 double azimuth = atan2(-cosD*cosL*sinH, sinD - sinL * ::sin(altitude));
487
488 result.set(azimuth, altitude);
489 return result;
490 }
491
492
493 //-------------------------------------------------------------------------
494 // The Sun
495 //-------------------------------------------------------------------------
496
497 //
498 // Parameters of the Sun's orbit as of the epoch Jan 0.0 1990
499 // Angles are in radians (after multiplying by CalendarAstronomer::PI/180)
500 //
501 #define JD_EPOCH 2447891.5 // Julian day of epoch
502
503 #define SUN_ETA_G (279.403303 * CalendarAstronomer::PI/180) // Ecliptic longitude at epoch
504 #define SUN_OMEGA_G (282.768422 * CalendarAstronomer::PI/180) // Ecliptic longitude of perigee
505 #define SUN_E 0.016713 // Eccentricity of orbit
506 //double sunR0 1.495585e8 // Semi-major axis in KM
507 //double sunTheta0 (0.533128 * CalendarAstronomer::PI/180) // Angular diameter at R0
508
509 // The following three methods, which compute the sun parameters
510 // given above for an arbitrary epoch (whatever time the object is
511 // set to), make only a small difference as compared to using the
512 // above constants. E.g., Sunset times might differ by ~12
513 // seconds. Furthermore, the eta-g computation is befuddled by
514 // Duffet-Smith's incorrect coefficients (p.86). I've corrected
515 // the first-order coefficient but the others may be off too - no
516 // way of knowing without consulting another source.
517
518 // /**
519 // * Return the sun's ecliptic longitude at perigee for the current time.
520 // * See Duffett-Smith, p. 86.
521 // * @return radians
522 // */
523 // private double getSunOmegaG() {
524 // double T = getJulianCentury();
525 // return (281.2208444 + (1.719175 + 0.000452778*T)*T) * DEG_RAD;
526 // }
527
528 // /**
529 // * Return the sun's ecliptic longitude for the current time.
530 // * See Duffett-Smith, p. 86.
531 // * @return radians
532 // */
533 // private double getSunEtaG() {
534 // double T = getJulianCentury();
535 // //return (279.6966778 + (36000.76892 + 0.0003025*T)*T) * DEG_RAD;
536 // //
537 // // The above line is from Duffett-Smith, and yields manifestly wrong
538 // // results. The below constant is derived empirically to match the
539 // // constant he gives for the 1990 EPOCH.
540 // //
541 // return (279.6966778 + (-0.3262541582718024 + 0.0003025*T)*T) * DEG_RAD;
542 // }
543
544 // /**
545 // * Return the sun's eccentricity of orbit for the current time.
546 // * See Duffett-Smith, p. 86.
547 // * @return double
548 // */
549 // private double getSunE() {
550 // double T = getJulianCentury();
551 // return 0.01675104 - (0.0000418 + 0.000000126*T)*T;
552 // }
553
554 /**
555 * The longitude of the sun at the time specified by this object.
556 * The longitude is measured in radians along the ecliptic
557 * from the "first point of Aries," the point at which the ecliptic
558 * crosses the earth's equatorial plane at the vernal equinox.
559 * <p>
560 * Currently, this method uses an approximation of the two-body Kepler's
561 * equation for the earth and the sun. It does not take into account the
562 * perturbations caused by the other planets, the moon, etc.
563 * @internal
564 * @deprecated ICU 2.4. This class may be removed or modified.
565 */
getSunLongitude()566 double CalendarAstronomer::getSunLongitude()
567 {
568 // See page 86 of "Practial Astronomy with your Calculator",
569 // by Peter Duffet-Smith, for details on the algorithm.
570
571 if (isINVALID(sunLongitude)) {
572 getSunLongitude(getJulianDay(), sunLongitude, meanAnomalySun);
573 }
574 return sunLongitude;
575 }
576
577 /**
578 * TODO Make this public when the entire class is package-private.
579 */
getSunLongitude(double jDay,double & longitude,double & meanAnomaly)580 /*public*/ void CalendarAstronomer::getSunLongitude(double jDay, double &longitude, double &meanAnomaly)
581 {
582 // See page 86 of "Practial Astronomy with your Calculator",
583 // by Peter Duffet-Smith, for details on the algorithm.
584
585 double day = jDay - JD_EPOCH; // Days since epoch
586
587 // Find the angular distance the sun in a fictitious
588 // circular orbit has travelled since the epoch.
589 double epochAngle = norm2PI(CalendarAstronomer_PI2/TROPICAL_YEAR*day);
590
591 // The epoch wasn't at the sun's perigee; find the angular distance
592 // since perigee, which is called the "mean anomaly"
593 meanAnomaly = norm2PI(epochAngle + SUN_ETA_G - SUN_OMEGA_G);
594
595 // Now find the "true anomaly", e.g. the real solar longitude
596 // by solving Kepler's equation for an elliptical orbit
597 // NOTE: The 3rd ed. of the book lists omega_g and eta_g in different
598 // equations; omega_g is to be correct.
599 longitude = norm2PI(trueAnomaly(meanAnomaly, SUN_E) + SUN_OMEGA_G);
600 }
601
602 /**
603 * The position of the sun at this object's current date and time,
604 * in equatorial coordinates.
605 * @internal
606 * @deprecated ICU 2.4. This class may be removed or modified.
607 */
getSunPosition(CalendarAstronomer::Equatorial & result)608 CalendarAstronomer::Equatorial& CalendarAstronomer::getSunPosition(CalendarAstronomer::Equatorial& result) {
609 return eclipticToEquatorial(result, getSunLongitude(), 0);
610 }
611
612
613 /**
614 * Constant representing the vernal equinox.
615 * For use with {@link #getSunTime getSunTime}.
616 * Note: In this case, "vernal" refers to the northern hemisphere's seasons.
617 * @internal
618 * @deprecated ICU 2.4. This class may be removed or modified.
619 */
620 /*double CalendarAstronomer::VERNAL_EQUINOX() {
621 return 0;
622 }*/
623
624 /**
625 * Constant representing the summer solstice.
626 * For use with {@link #getSunTime getSunTime}.
627 * Note: In this case, "summer" refers to the northern hemisphere's seasons.
628 * @internal
629 * @deprecated ICU 2.4. This class may be removed or modified.
630 */
SUMMER_SOLSTICE()631 double CalendarAstronomer::SUMMER_SOLSTICE() {
632 return (CalendarAstronomer::PI/2);
633 }
634
635 /**
636 * Constant representing the autumnal equinox.
637 * For use with {@link #getSunTime getSunTime}.
638 * Note: In this case, "autumn" refers to the northern hemisphere's seasons.
639 * @internal
640 * @deprecated ICU 2.4. This class may be removed or modified.
641 */
642 /*double CalendarAstronomer::AUTUMN_EQUINOX() {
643 return (CalendarAstronomer::PI);
644 }*/
645
646 /**
647 * Constant representing the winter solstice.
648 * For use with {@link #getSunTime getSunTime}.
649 * Note: In this case, "winter" refers to the northern hemisphere's seasons.
650 * @internal
651 * @deprecated ICU 2.4. This class may be removed or modified.
652 */
653 /*double CalendarAstronomer::WINTER_SOLSTICE() {
654 return ((CalendarAstronomer::PI*3)/2);
655 }*/
656
~AngleFunc()657 CalendarAstronomer::AngleFunc::~AngleFunc() {}
658
659 /**
660 * Find the next time at which the sun's ecliptic longitude will have
661 * the desired value.
662 * @internal
663 * @deprecated ICU 2.4. This class may be removed or modified.
664 */
665 class SunTimeAngleFunc : public CalendarAstronomer::AngleFunc {
666 public:
eval(CalendarAstronomer & a)667 virtual double eval(CalendarAstronomer& a) { return a.getSunLongitude(); }
668 };
669
getSunTime(double desired,UBool next)670 UDate CalendarAstronomer::getSunTime(double desired, UBool next)
671 {
672 SunTimeAngleFunc func;
673 return timeOfAngle( func,
674 desired,
675 TROPICAL_YEAR,
676 MINUTE_MS,
677 next);
678 }
679
~CoordFunc()680 CalendarAstronomer::CoordFunc::~CoordFunc() {}
681
682 class RiseSetCoordFunc : public CalendarAstronomer::CoordFunc {
683 public:
eval(CalendarAstronomer::Equatorial & result,CalendarAstronomer & a)684 virtual void eval(CalendarAstronomer::Equatorial& result, CalendarAstronomer&a) { a.getSunPosition(result); }
685 };
686
getSunRiseSet(UBool rise)687 UDate CalendarAstronomer::getSunRiseSet(UBool rise)
688 {
689 UDate t0 = fTime;
690
691 // Make a rough guess: 6am or 6pm local time on the current day
692 double noon = Math::floorDivide(fTime + fGmtOffset, (double)DAY_MS)*DAY_MS - fGmtOffset + (12*HOUR_MS);
693
694 U_DEBUG_ASTRO_MSG(("Noon=%.2lf, %sL, gmtoff %.2lf\n", noon, debug_astro_date(noon+fGmtOffset), fGmtOffset));
695 setTime(noon + ((rise ? -6 : 6) * HOUR_MS));
696 U_DEBUG_ASTRO_MSG(("added %.2lf ms as a guess,\n", ((rise ? -6. : 6.) * HOUR_MS)));
697
698 RiseSetCoordFunc func;
699 double t = riseOrSet(func,
700 rise,
701 .533 * DEG_RAD, // Angular Diameter
702 34. /60.0 * DEG_RAD, // Refraction correction
703 MINUTE_MS / 12.); // Desired accuracy
704
705 setTime(t0);
706 return t;
707 }
708
709 // Commented out - currently unused. ICU 2.6, Alan
710 // //-------------------------------------------------------------------------
711 // // Alternate Sun Rise/Set
712 // // See Duffett-Smith p.93
713 // //-------------------------------------------------------------------------
714 //
715 // // This yields worse results (as compared to USNO data) than getSunRiseSet().
716 // /**
717 // * TODO Make this when the entire class is package-private.
718 // */
719 // /*public*/ long getSunRiseSet2(boolean rise) {
720 // // 1. Calculate coordinates of the sun's center for midnight
721 // double jd = uprv_floor(getJulianDay() - 0.5) + 0.5;
722 // double[] sl = getSunLongitude(jd);// double lambda1 = sl[0];
723 // Equatorial pos1 = eclipticToEquatorial(lambda1, 0);
724 //
725 // // 2. Add ... to lambda to get position 24 hours later
726 // double lambda2 = lambda1 + 0.985647*DEG_RAD;
727 // Equatorial pos2 = eclipticToEquatorial(lambda2, 0);
728 //
729 // // 3. Calculate LSTs of rising and setting for these two positions
730 // double tanL = ::tan(fLatitude);
731 // double H = ::acos(-tanL * ::tan(pos1.declination));
732 // double lst1r = (CalendarAstronomer_PI2 + pos1.ascension - H) * 24 / CalendarAstronomer_PI2;
733 // double lst1s = (pos1.ascension + H) * 24 / CalendarAstronomer_PI2;
734 // H = ::acos(-tanL * ::tan(pos2.declination));
735 // double lst2r = (CalendarAstronomer_PI2-H + pos2.ascension ) * 24 / CalendarAstronomer_PI2;
736 // double lst2s = (H + pos2.ascension ) * 24 / CalendarAstronomer_PI2;
737 // if (lst1r > 24) lst1r -= 24;
738 // if (lst1s > 24) lst1s -= 24;
739 // if (lst2r > 24) lst2r -= 24;
740 // if (lst2s > 24) lst2s -= 24;
741 //
742 // // 4. Convert LSTs to GSTs. If GST1 > GST2, add 24 to GST2.
743 // double gst1r = lstToGst(lst1r);
744 // double gst1s = lstToGst(lst1s);
745 // double gst2r = lstToGst(lst2r);
746 // double gst2s = lstToGst(lst2s);
747 // if (gst1r > gst2r) gst2r += 24;
748 // if (gst1s > gst2s) gst2s += 24;
749 //
750 // // 5. Calculate GST at 0h UT of this date
751 // double t00 = utToGst(0);
752 //
753 // // 6. Calculate GST at 0h on the observer's longitude
754 // double offset = ::round(fLongitude*12/PI); // p.95 step 6; he _rounds_ to nearest 15 deg.
755 // double t00p = t00 - offset*1.002737909;
756 // if (t00p < 0) t00p += 24; // do NOT normalize
757 //
758 // // 7. Adjust
759 // if (gst1r < t00p) {
760 // gst1r += 24;
761 // gst2r += 24;
762 // }
763 // if (gst1s < t00p) {
764 // gst1s += 24;
765 // gst2s += 24;
766 // }
767 //
768 // // 8.
769 // double gstr = (24.07*gst1r-t00*(gst2r-gst1r))/(24.07+gst1r-gst2r);
770 // double gsts = (24.07*gst1s-t00*(gst2s-gst1s))/(24.07+gst1s-gst2s);
771 //
772 // // 9. Correct for parallax, refraction, and sun's diameter
773 // double dec = (pos1.declination + pos2.declination) / 2;
774 // double psi = ::acos(sin(fLatitude) / cos(dec));
775 // double x = 0.830725 * DEG_RAD; // parallax+refraction+diameter
776 // double y = ::asin(sin(x) / ::sin(psi)) * RAD_DEG;
777 // double delta_t = 240 * y / cos(dec) / 3600; // hours
778 //
779 // // 10. Add correction to GSTs, subtract from GSTr
780 // gstr -= delta_t;
781 // gsts += delta_t;
782 //
783 // // 11. Convert GST to UT and then to local civil time
784 // double ut = gstToUt(rise ? gstr : gsts);
785 // //System.out.println((rise?"rise=":"set=") + ut + ", delta_t=" + delta_t);
786 // long midnight = DAY_MS * (time / DAY_MS); // Find UT midnight on this day
787 // return midnight + (long) (ut * 3600000);
788 // }
789
790 // Commented out - currently unused. ICU 2.6, Alan
791 // /**
792 // * Convert local sidereal time to Greenwich sidereal time.
793 // * Section 15. Duffett-Smith p.21
794 // * @param lst in hours (0..24)
795 // * @return GST in hours (0..24)
796 // */
797 // double lstToGst(double lst) {
798 // double delta = fLongitude * 24 / CalendarAstronomer_PI2;
799 // return normalize(lst - delta, 24);
800 // }
801
802 // Commented out - currently unused. ICU 2.6, Alan
803 // /**
804 // * Convert UT to GST on this date.
805 // * Section 12. Duffett-Smith p.17
806 // * @param ut in hours
807 // * @return GST in hours
808 // */
809 // double utToGst(double ut) {
810 // return normalize(getT0() + ut*1.002737909, 24);
811 // }
812
813 // Commented out - currently unused. ICU 2.6, Alan
814 // /**
815 // * Convert GST to UT on this date.
816 // * Section 13. Duffett-Smith p.18
817 // * @param gst in hours
818 // * @return UT in hours
819 // */
820 // double gstToUt(double gst) {
821 // return normalize(gst - getT0(), 24) * 0.9972695663;
822 // }
823
824 // Commented out - currently unused. ICU 2.6, Alan
825 // double getT0() {
826 // // Common computation for UT <=> GST
827 //
828 // // Find JD for 0h UT
829 // double jd = uprv_floor(getJulianDay() - 0.5) + 0.5;
830 //
831 // double s = jd - 2451545.0;
832 // double t = s / 36525.0;
833 // double t0 = 6.697374558 + (2400.051336 + 0.000025862*t)*t;
834 // return t0;
835 // }
836
837 // Commented out - currently unused. ICU 2.6, Alan
838 // //-------------------------------------------------------------------------
839 // // Alternate Sun Rise/Set
840 // // See sci.astro FAQ
841 // // http://www.faqs.org/faqs/astronomy/faq/part3/section-5.html
842 // //-------------------------------------------------------------------------
843 //
844 // // Note: This method appears to produce inferior accuracy as
845 // // compared to getSunRiseSet().
846 //
847 // /**
848 // * TODO Make this when the entire class is package-private.
849 // */
850 // /*public*/ long getSunRiseSet3(boolean rise) {
851 //
852 // // Compute day number for 0.0 Jan 2000 epoch
853 // double d = (double)(time - EPOCH_2000_MS) / DAY_MS;
854 //
855 // // Now compute the Local Sidereal Time, LST:
856 // //
857 // double LST = 98.9818 + 0.985647352 * d + /*UT*15 + long*/
858 // fLongitude*RAD_DEG;
859 // //
860 // // (east long. positive). Note that LST is here expressed in degrees,
861 // // where 15 degrees corresponds to one hour. Since LST really is an angle,
862 // // it's convenient to use one unit---degrees---throughout.
863 //
864 // // COMPUTING THE SUN'S POSITION
865 // // ----------------------------
866 // //
867 // // To be able to compute the Sun's rise/set times, you need to be able to
868 // // compute the Sun's position at any time. First compute the "day
869 // // number" d as outlined above, for the desired moment. Next compute:
870 // //
871 // double oblecl = 23.4393 - 3.563E-7 * d;
872 // //
873 // double w = 282.9404 + 4.70935E-5 * d;
874 // double M = 356.0470 + 0.9856002585 * d;
875 // double e = 0.016709 - 1.151E-9 * d;
876 // //
877 // // This is the obliquity of the ecliptic, plus some of the elements of
878 // // the Sun's apparent orbit (i.e., really the Earth's orbit): w =
879 // // argument of perihelion, M = mean anomaly, e = eccentricity.
880 // // Semi-major axis is here assumed to be exactly 1.0 (while not strictly
881 // // true, this is still an accurate approximation). Next compute E, the
882 // // eccentric anomaly:
883 // //
884 // double E = M + e*(180/PI) * ::sin(M*DEG_RAD) * ( 1.0 + e*cos(M*DEG_RAD) );
885 // //
886 // // where E and M are in degrees. This is it---no further iterations are
887 // // needed because we know e has a sufficiently small value. Next compute
888 // // the true anomaly, v, and the distance, r:
889 // //
890 // /* r * cos(v) = */ double A = cos(E*DEG_RAD) - e;
891 // /* r * ::sin(v) = */ double B = ::sqrt(1 - e*e) * ::sin(E*DEG_RAD);
892 // //
893 // // and
894 // //
895 // // r = sqrt( A*A + B*B )
896 // double v = ::atan2( B, A )*RAD_DEG;
897 // //
898 // // The Sun's true longitude, slon, can now be computed:
899 // //
900 // double slon = v + w;
901 // //
902 // // Since the Sun is always at the ecliptic (or at least very very close to
903 // // it), we can use simplified formulae to convert slon (the Sun's ecliptic
904 // // longitude) to sRA and sDec (the Sun's RA and Dec):
905 // //
906 // // ::sin(slon) * cos(oblecl)
907 // // tan(sRA) = -------------------------
908 // // cos(slon)
909 // //
910 // // ::sin(sDec) = ::sin(oblecl) * ::sin(slon)
911 // //
912 // // As was the case when computing az, the Azimuth, if possible use an
913 // // atan2() function to compute sRA.
914 //
915 // double sRA = ::atan2(sin(slon*DEG_RAD) * cos(oblecl*DEG_RAD), cos(slon*DEG_RAD))*RAD_DEG;
916 //
917 // double sin_sDec = ::sin(oblecl*DEG_RAD) * ::sin(slon*DEG_RAD);
918 // double sDec = ::asin(sin_sDec)*RAD_DEG;
919 //
920 // // COMPUTING RISE AND SET TIMES
921 // // ----------------------------
922 // //
923 // // To compute when an object rises or sets, you must compute when it
924 // // passes the meridian and the HA of rise/set. Then the rise time is
925 // // the meridian time minus HA for rise/set, and the set time is the
926 // // meridian time plus the HA for rise/set.
927 // //
928 // // To find the meridian time, compute the Local Sidereal Time at 0h local
929 // // time (or 0h UT if you prefer to work in UT) as outlined above---name
930 // // that quantity LST0. The Meridian Time, MT, will now be:
931 // //
932 // // MT = RA - LST0
933 // double MT = normalize(sRA - LST, 360);
934 // //
935 // // where "RA" is the object's Right Ascension (in degrees!). If negative,
936 // // add 360 deg to MT. If the object is the Sun, leave the time as it is,
937 // // but if it's stellar, multiply MT by 365.2422/366.2422, to convert from
938 // // sidereal to solar time. Now, compute HA for rise/set, name that
939 // // quantity HA0:
940 // //
941 // // ::sin(h0) - ::sin(lat) * ::sin(Dec)
942 // // cos(HA0) = ---------------------------------
943 // // cos(lat) * cos(Dec)
944 // //
945 // // where h0 is the altitude selected to represent rise/set. For a purely
946 // // mathematical horizon, set h0 = 0 and simplify to:
947 // //
948 // // cos(HA0) = - tan(lat) * tan(Dec)
949 // //
950 // // If you want to account for refraction on the atmosphere, set h0 = -35/60
951 // // degrees (-35 arc minutes), and if you want to compute the rise/set times
952 // // for the Sun's upper limb, set h0 = -50/60 (-50 arc minutes).
953 // //
954 // double h0 = -50/60 * DEG_RAD;
955 //
956 // double HA0 = ::acos(
957 // (sin(h0) - ::sin(fLatitude) * sin_sDec) /
958 // (cos(fLatitude) * cos(sDec*DEG_RAD)))*RAD_DEG;
959 //
960 // // When HA0 has been computed, leave it as it is for the Sun but multiply
961 // // by 365.2422/366.2422 for stellar objects, to convert from sidereal to
962 // // solar time. Finally compute:
963 // //
964 // // Rise time = MT - HA0
965 // // Set time = MT + HA0
966 // //
967 // // convert the times from degrees to hours by dividing by 15.
968 // //
969 // // If you'd like to check that your calculations are accurate or just
970 // // need a quick result, check the USNO's Sun or Moon Rise/Set Table,
971 // // <URL:http://aa.usno.navy.mil/AA/data/docs/RS_OneYear.html>.
972 //
973 // double result = MT + (rise ? -HA0 : HA0); // in degrees
974 //
975 // // Find UT midnight on this day
976 // long midnight = DAY_MS * (time / DAY_MS);
977 //
978 // return midnight + (long) (result * 3600000 / 15);
979 // }
980
981 //-------------------------------------------------------------------------
982 // The Moon
983 //-------------------------------------------------------------------------
984
985 #define moonL0 (318.351648 * CalendarAstronomer::PI/180 ) // Mean long. at epoch
986 #define moonP0 ( 36.340410 * CalendarAstronomer::PI/180 ) // Mean long. of perigee
987 #define moonN0 ( 318.510107 * CalendarAstronomer::PI/180 ) // Mean long. of node
988 #define moonI ( 5.145366 * CalendarAstronomer::PI/180 ) // Inclination of orbit
989 #define moonE ( 0.054900 ) // Eccentricity of orbit
990
991 // These aren't used right now
992 #define moonA ( 3.84401e5 ) // semi-major axis (km)
993 #define moonT0 ( 0.5181 * CalendarAstronomer::PI/180 ) // Angular size at distance A
994 #define moonPi ( 0.9507 * CalendarAstronomer::PI/180 ) // Parallax at distance A
995
996 /**
997 * The position of the moon at the time set on this
998 * object, in equatorial coordinates.
999 * @internal
1000 * @deprecated ICU 2.4. This class may be removed or modified.
1001 */
getMoonPosition()1002 const CalendarAstronomer::Equatorial& CalendarAstronomer::getMoonPosition()
1003 {
1004 //
1005 // See page 142 of "Practial Astronomy with your Calculator",
1006 // by Peter Duffet-Smith, for details on the algorithm.
1007 //
1008 if (moonPositionSet == FALSE) {
1009 // Calculate the solar longitude. Has the side effect of
1010 // filling in "meanAnomalySun" as well.
1011 getSunLongitude();
1012
1013 //
1014 // Find the # of days since the epoch of our orbital parameters.
1015 // TODO: Convert the time of day portion into ephemeris time
1016 //
1017 double day = getJulianDay() - JD_EPOCH; // Days since epoch
1018
1019 // Calculate the mean longitude and anomaly of the moon, based on
1020 // a circular orbit. Similar to the corresponding solar calculation.
1021 double meanLongitude = norm2PI(13.1763966*PI/180*day + moonL0);
1022 meanAnomalyMoon = norm2PI(meanLongitude - 0.1114041*PI/180 * day - moonP0);
1023
1024 //
1025 // Calculate the following corrections:
1026 // Evection: the sun's gravity affects the moon's eccentricity
1027 // Annual Eqn: variation in the effect due to earth-sun distance
1028 // A3: correction factor (for ???)
1029 //
1030 double evection = 1.2739*PI/180 * ::sin(2 * (meanLongitude - sunLongitude)
1031 - meanAnomalyMoon);
1032 double annual = 0.1858*PI/180 * ::sin(meanAnomalySun);
1033 double a3 = 0.3700*PI/180 * ::sin(meanAnomalySun);
1034
1035 meanAnomalyMoon += evection - annual - a3;
1036
1037 //
1038 // More correction factors:
1039 // center equation of the center correction
1040 // a4 yet another error correction (???)
1041 //
1042 // TODO: Skip the equation of the center correction and solve Kepler's eqn?
1043 //
1044 double center = 6.2886*PI/180 * ::sin(meanAnomalyMoon);
1045 double a4 = 0.2140*PI/180 * ::sin(2 * meanAnomalyMoon);
1046
1047 // Now find the moon's corrected longitude
1048 moonLongitude = meanLongitude + evection + center - annual + a4;
1049
1050 //
1051 // And finally, find the variation, caused by the fact that the sun's
1052 // gravitational pull on the moon varies depending on which side of
1053 // the earth the moon is on
1054 //
1055 double variation = 0.6583*CalendarAstronomer::PI/180 * ::sin(2*(moonLongitude - sunLongitude));
1056
1057 moonLongitude += variation;
1058
1059 //
1060 // What we've calculated so far is the moon's longitude in the plane
1061 // of its own orbit. Now map to the ecliptic to get the latitude
1062 // and longitude. First we need to find the longitude of the ascending
1063 // node, the position on the ecliptic where it is crossed by the moon's
1064 // orbit as it crosses from the southern to the northern hemisphere.
1065 //
1066 double nodeLongitude = norm2PI(moonN0 - 0.0529539*PI/180 * day);
1067
1068 nodeLongitude -= 0.16*PI/180 * ::sin(meanAnomalySun);
1069
1070 double y = ::sin(moonLongitude - nodeLongitude);
1071 double x = cos(moonLongitude - nodeLongitude);
1072
1073 moonEclipLong = ::atan2(y*cos(moonI), x) + nodeLongitude;
1074 double moonEclipLat = ::asin(y * ::sin(moonI));
1075
1076 eclipticToEquatorial(moonPosition, moonEclipLong, moonEclipLat);
1077 moonPositionSet = TRUE;
1078 }
1079 return moonPosition;
1080 }
1081
1082 /**
1083 * The "age" of the moon at the time specified in this object.
1084 * This is really the angle between the
1085 * current ecliptic longitudes of the sun and the moon,
1086 * measured in radians.
1087 *
1088 * @see #getMoonPhase
1089 * @internal
1090 * @deprecated ICU 2.4. This class may be removed or modified.
1091 */
getMoonAge()1092 double CalendarAstronomer::getMoonAge() {
1093 // See page 147 of "Practial Astronomy with your Calculator",
1094 // by Peter Duffet-Smith, for details on the algorithm.
1095 //
1096 // Force the moon's position to be calculated. We're going to use
1097 // some the intermediate results cached during that calculation.
1098 //
1099 getMoonPosition();
1100
1101 return norm2PI(moonEclipLong - sunLongitude);
1102 }
1103
1104 /**
1105 * Calculate the phase of the moon at the time set in this object.
1106 * The returned phase is a <code>double</code> in the range
1107 * <code>0 <= phase < 1</code>, interpreted as follows:
1108 * <ul>
1109 * <li>0.00: New moon
1110 * <li>0.25: First quarter
1111 * <li>0.50: Full moon
1112 * <li>0.75: Last quarter
1113 * </ul>
1114 *
1115 * @see #getMoonAge
1116 * @internal
1117 * @deprecated ICU 2.4. This class may be removed or modified.
1118 */
getMoonPhase()1119 double CalendarAstronomer::getMoonPhase() {
1120 // See page 147 of "Practial Astronomy with your Calculator",
1121 // by Peter Duffet-Smith, for details on the algorithm.
1122 return 0.5 * (1 - cos(getMoonAge()));
1123 }
1124
1125 /**
1126 * Constant representing a new moon.
1127 * For use with {@link #getMoonTime getMoonTime}
1128 * @internal
1129 * @deprecated ICU 2.4. This class may be removed or modified.
1130 */
1131 /*const CalendarAstronomer::MoonAge CalendarAstronomer::NEW_MOON() {
1132 return CalendarAstronomer::MoonAge(0);
1133 }*/
1134
1135 /**
1136 * Constant representing the moon's first quarter.
1137 * For use with {@link #getMoonTime getMoonTime}
1138 * @internal
1139 * @deprecated ICU 2.4. This class may be removed or modified.
1140 */
1141 /*const CalendarAstronomer::MoonAge CalendarAstronomer::FIRST_QUARTER() {
1142 return CalendarAstronomer::MoonAge(CalendarAstronomer::PI/2);
1143 }*/
1144
1145 /**
1146 * Constant representing a full moon.
1147 * For use with {@link #getMoonTime getMoonTime}
1148 * @internal
1149 * @deprecated ICU 2.4. This class may be removed or modified.
1150 */
FULL_MOON()1151 const CalendarAstronomer::MoonAge CalendarAstronomer::FULL_MOON() {
1152 return CalendarAstronomer::MoonAge(CalendarAstronomer::PI);
1153 }
1154 /**
1155 * Constant representing the moon's last quarter.
1156 * For use with {@link #getMoonTime getMoonTime}
1157 * @internal
1158 * @deprecated ICU 2.4. This class may be removed or modified.
1159 */
1160
1161 class MoonTimeAngleFunc : public CalendarAstronomer::AngleFunc {
1162 public:
eval(CalendarAstronomer & a)1163 virtual double eval(CalendarAstronomer&a) { return a.getMoonAge(); }
1164 };
1165
1166 /*const CalendarAstronomer::MoonAge CalendarAstronomer::LAST_QUARTER() {
1167 return CalendarAstronomer::MoonAge((CalendarAstronomer::PI*3)/2);
1168 }*/
1169
1170 /**
1171 * Find the next or previous time at which the Moon's ecliptic
1172 * longitude will have the desired value.
1173 * <p>
1174 * @param desired The desired longitude.
1175 * @param next <tt>true</tt> if the next occurrance of the phase
1176 * is desired, <tt>false</tt> for the previous occurrance.
1177 * @internal
1178 * @deprecated ICU 2.4. This class may be removed or modified.
1179 */
getMoonTime(double desired,UBool next)1180 UDate CalendarAstronomer::getMoonTime(double desired, UBool next)
1181 {
1182 MoonTimeAngleFunc func;
1183 return timeOfAngle( func,
1184 desired,
1185 SYNODIC_MONTH,
1186 MINUTE_MS,
1187 next);
1188 }
1189
1190 /**
1191 * Find the next or previous time at which the moon will be in the
1192 * desired phase.
1193 * <p>
1194 * @param desired The desired phase of the moon.
1195 * @param next <tt>true</tt> if the next occurrance of the phase
1196 * is desired, <tt>false</tt> for the previous occurrance.
1197 * @internal
1198 * @deprecated ICU 2.4. This class may be removed or modified.
1199 */
getMoonTime(const CalendarAstronomer::MoonAge & desired,UBool next)1200 UDate CalendarAstronomer::getMoonTime(const CalendarAstronomer::MoonAge& desired, UBool next) {
1201 return getMoonTime(desired.value, next);
1202 }
1203
1204 class MoonRiseSetCoordFunc : public CalendarAstronomer::CoordFunc {
1205 public:
eval(CalendarAstronomer::Equatorial & result,CalendarAstronomer & a)1206 virtual void eval(CalendarAstronomer::Equatorial& result, CalendarAstronomer&a) { result = a.getMoonPosition(); }
1207 };
1208
1209 /**
1210 * Returns the time (GMT) of sunrise or sunset on the local date to which
1211 * this calendar is currently set.
1212 * @internal
1213 * @deprecated ICU 2.4. This class may be removed or modified.
1214 */
getMoonRiseSet(UBool rise)1215 UDate CalendarAstronomer::getMoonRiseSet(UBool rise)
1216 {
1217 MoonRiseSetCoordFunc func;
1218 return riseOrSet(func,
1219 rise,
1220 .533 * DEG_RAD, // Angular Diameter
1221 34 /60.0 * DEG_RAD, // Refraction correction
1222 MINUTE_MS); // Desired accuracy
1223 }
1224
1225 //-------------------------------------------------------------------------
1226 // Interpolation methods for finding the time at which a given event occurs
1227 //-------------------------------------------------------------------------
1228
timeOfAngle(AngleFunc & func,double desired,double periodDays,double epsilon,UBool next)1229 UDate CalendarAstronomer::timeOfAngle(AngleFunc& func, double desired,
1230 double periodDays, double epsilon, UBool next)
1231 {
1232 // Find the value of the function at the current time
1233 double lastAngle = func.eval(*this);
1234
1235 // Find out how far we are from the desired angle
1236 double deltaAngle = norm2PI(desired - lastAngle) ;
1237
1238 // Using the average period, estimate the next (or previous) time at
1239 // which the desired angle occurs.
1240 double deltaT = (deltaAngle + (next ? 0.0 : - CalendarAstronomer_PI2 )) * (periodDays*DAY_MS) / CalendarAstronomer_PI2;
1241
1242 double lastDeltaT = deltaT; // Liu
1243 UDate startTime = fTime; // Liu
1244
1245 setTime(fTime + uprv_ceil(deltaT));
1246
1247 // Now iterate until we get the error below epsilon. Throughout
1248 // this loop we use normPI to get values in the range -Pi to Pi,
1249 // since we're using them as correction factors rather than absolute angles.
1250 do {
1251 // Evaluate the function at the time we've estimated
1252 double angle = func.eval(*this);
1253
1254 // Find the # of milliseconds per radian at this point on the curve
1255 double factor = uprv_fabs(deltaT / normPI(angle-lastAngle));
1256
1257 // Correct the time estimate based on how far off the angle is
1258 deltaT = normPI(desired - angle) * factor;
1259
1260 // HACK:
1261 //
1262 // If abs(deltaT) begins to diverge we need to quit this loop.
1263 // This only appears to happen when attempting to locate, for
1264 // example, a new moon on the day of the new moon. E.g.:
1265 //
1266 // This result is correct:
1267 // newMoon(7508(Mon Jul 23 00:00:00 CST 1990,false))=
1268 // Sun Jul 22 10:57:41 CST 1990
1269 //
1270 // But attempting to make the same call a day earlier causes deltaT
1271 // to diverge:
1272 // CalendarAstronomer.timeOfAngle() diverging: 1.348508727575625E9 ->
1273 // 1.3649828540224032E9
1274 // newMoon(7507(Sun Jul 22 00:00:00 CST 1990,false))=
1275 // Sun Jul 08 13:56:15 CST 1990
1276 //
1277 // As a temporary solution, we catch this specific condition and
1278 // adjust our start time by one eighth period days (either forward
1279 // or backward) and try again.
1280 // Liu 11/9/00
1281 if (uprv_fabs(deltaT) > uprv_fabs(lastDeltaT)) {
1282 double delta = uprv_ceil (periodDays * DAY_MS / 8.0);
1283 setTime(startTime + (next ? delta : -delta));
1284 return timeOfAngle(func, desired, periodDays, epsilon, next);
1285 }
1286
1287 lastDeltaT = deltaT;
1288 lastAngle = angle;
1289
1290 setTime(fTime + uprv_ceil(deltaT));
1291 }
1292 while (uprv_fabs(deltaT) > epsilon);
1293
1294 return fTime;
1295 }
1296
riseOrSet(CoordFunc & func,UBool rise,double diameter,double refraction,double epsilon)1297 UDate CalendarAstronomer::riseOrSet(CoordFunc& func, UBool rise,
1298 double diameter, double refraction,
1299 double epsilon)
1300 {
1301 Equatorial pos;
1302 double tanL = ::tan(fLatitude);
1303 double deltaT = 0;
1304 int32_t count = 0;
1305
1306 //
1307 // Calculate the object's position at the current time, then use that
1308 // position to calculate the time of rising or setting. The position
1309 // will be different at that time, so iterate until the error is allowable.
1310 //
1311 U_DEBUG_ASTRO_MSG(("setup rise=%s, dia=%.3lf, ref=%.3lf, eps=%.3lf\n",
1312 rise?"T":"F", diameter, refraction, epsilon));
1313 do {
1314 // See "Practical Astronomy With Your Calculator, section 33.
1315 func.eval(pos, *this);
1316 double angle = ::acos(-tanL * ::tan(pos.declination));
1317 double lst = ((rise ? CalendarAstronomer_PI2-angle : angle) + pos.ascension ) * 24 / CalendarAstronomer_PI2;
1318
1319 // Convert from LST to Universal Time.
1320 UDate newTime = lstToUT( lst );
1321
1322 deltaT = newTime - fTime;
1323 setTime(newTime);
1324 U_DEBUG_ASTRO_MSG(("%d] dT=%.3lf, angle=%.3lf, lst=%.3lf, A=%.3lf/D=%.3lf\n",
1325 count, deltaT, angle, lst, pos.ascension, pos.declination));
1326 }
1327 while (++ count < 5 && uprv_fabs(deltaT) > epsilon);
1328
1329 // Calculate the correction due to refraction and the object's angular diameter
1330 double cosD = ::cos(pos.declination);
1331 double psi = ::acos(sin(fLatitude) / cosD);
1332 double x = diameter / 2 + refraction;
1333 double y = ::asin(sin(x) / ::sin(psi));
1334 long delta = (long)((240 * y * RAD_DEG / cosD)*SECOND_MS);
1335
1336 return fTime + (rise ? -delta : delta);
1337 }
1338
1339 /**
1340 * Find the "true anomaly" (longitude) of an object from
1341 * its mean anomaly and the eccentricity of its orbit. This uses
1342 * an iterative solution to Kepler's equation.
1343 *
1344 * @param meanAnomaly The object's longitude calculated as if it were in
1345 * a regular, circular orbit, measured in radians
1346 * from the point of perigee.
1347 *
1348 * @param eccentricity The eccentricity of the orbit
1349 *
1350 * @return The true anomaly (longitude) measured in radians
1351 */
trueAnomaly(double meanAnomaly,double eccentricity)1352 double CalendarAstronomer::trueAnomaly(double meanAnomaly, double eccentricity)
1353 {
1354 // First, solve Kepler's equation iteratively
1355 // Duffett-Smith, p.90
1356 double delta;
1357 double E = meanAnomaly;
1358 do {
1359 delta = E - eccentricity * ::sin(E) - meanAnomaly;
1360 E = E - delta / (1 - eccentricity * ::cos(E));
1361 }
1362 while (uprv_fabs(delta) > 1e-5); // epsilon = 1e-5 rad
1363
1364 return 2.0 * ::atan( ::tan(E/2) * ::sqrt( (1+eccentricity)
1365 /(1-eccentricity) ) );
1366 }
1367
1368 /**
1369 * Return the obliquity of the ecliptic (the angle between the ecliptic
1370 * and the earth's equator) at the current time. This varies due to
1371 * the precession of the earth's axis.
1372 *
1373 * @return the obliquity of the ecliptic relative to the equator,
1374 * measured in radians.
1375 */
eclipticObliquity()1376 double CalendarAstronomer::eclipticObliquity() {
1377 if (isINVALID(eclipObliquity)) {
1378 const double epoch = 2451545.0; // 2000 AD, January 1.5
1379
1380 double T = (getJulianDay() - epoch) / 36525;
1381
1382 eclipObliquity = 23.439292
1383 - 46.815/3600 * T
1384 - 0.0006/3600 * T*T
1385 + 0.00181/3600 * T*T*T;
1386
1387 eclipObliquity *= DEG_RAD;
1388 }
1389 return eclipObliquity;
1390 }
1391
1392
1393 //-------------------------------------------------------------------------
1394 // Private data
1395 //-------------------------------------------------------------------------
clearCache()1396 void CalendarAstronomer::clearCache() {
1397 const double INVALID = uprv_getNaN();
1398
1399 julianDay = INVALID;
1400 julianCentury = INVALID;
1401 sunLongitude = INVALID;
1402 meanAnomalySun = INVALID;
1403 moonLongitude = INVALID;
1404 moonEclipLong = INVALID;
1405 meanAnomalyMoon = INVALID;
1406 eclipObliquity = INVALID;
1407 siderealTime = INVALID;
1408 siderealT0 = INVALID;
1409 moonPositionSet = FALSE;
1410 }
1411
1412 //private static void out(String s) {
1413 // System.out.println(s);
1414 //}
1415
1416 //private static String deg(double rad) {
1417 // return Double.toString(rad * RAD_DEG);
1418 //}
1419
1420 //private static String hours(long ms) {
1421 // return Double.toString((double)ms / HOUR_MS) + " hours";
1422 //}
1423
1424 /**
1425 * @internal
1426 * @deprecated ICU 2.4. This class may be removed or modified.
1427 */
1428 /*UDate CalendarAstronomer::local(UDate localMillis) {
1429 // TODO - srl ?
1430 TimeZone *tz = TimeZone::createDefault();
1431 int32_t rawOffset;
1432 int32_t dstOffset;
1433 UErrorCode status = U_ZERO_ERROR;
1434 tz->getOffset(localMillis, TRUE, rawOffset, dstOffset, status);
1435 delete tz;
1436 return localMillis - rawOffset;
1437 }*/
1438
1439 // Debugging functions
toString() const1440 UnicodeString CalendarAstronomer::Ecliptic::toString() const
1441 {
1442 #ifdef U_DEBUG_ASTRO
1443 char tmp[800];
1444 sprintf(tmp, "[%.5f,%.5f]", longitude*RAD_DEG, latitude*RAD_DEG);
1445 return UnicodeString(tmp, "");
1446 #else
1447 return UnicodeString();
1448 #endif
1449 }
1450
toString() const1451 UnicodeString CalendarAstronomer::Equatorial::toString() const
1452 {
1453 #ifdef U_DEBUG_ASTRO
1454 char tmp[400];
1455 sprintf(tmp, "%f,%f",
1456 (ascension*RAD_DEG), (declination*RAD_DEG));
1457 return UnicodeString(tmp, "");
1458 #else
1459 return UnicodeString();
1460 #endif
1461 }
1462
toString() const1463 UnicodeString CalendarAstronomer::Horizon::toString() const
1464 {
1465 #ifdef U_DEBUG_ASTRO
1466 char tmp[800];
1467 sprintf(tmp, "[%.5f,%.5f]", altitude*RAD_DEG, azimuth*RAD_DEG);
1468 return UnicodeString(tmp, "");
1469 #else
1470 return UnicodeString();
1471 #endif
1472 }
1473
1474
1475 // static private String radToHms(double angle) {
1476 // int hrs = (int) (angle*RAD_HOUR);
1477 // int min = (int)((angle*RAD_HOUR - hrs) * 60);
1478 // int sec = (int)((angle*RAD_HOUR - hrs - min/60.0) * 3600);
1479
1480 // return Integer.toString(hrs) + "h" + min + "m" + sec + "s";
1481 // }
1482
1483 // static private String radToDms(double angle) {
1484 // int deg = (int) (angle*RAD_DEG);
1485 // int min = (int)((angle*RAD_DEG - deg) * 60);
1486 // int sec = (int)((angle*RAD_DEG - deg - min/60.0) * 3600);
1487
1488 // return Integer.toString(deg) + "\u00b0" + min + "'" + sec + "\"";
1489 // }
1490
1491 // =============== Calendar Cache ================
1492
createCache(CalendarCache ** cache,UErrorCode & status)1493 void CalendarCache::createCache(CalendarCache** cache, UErrorCode& status) {
1494 ucln_i18n_registerCleanup(UCLN_I18N_ASTRO_CALENDAR, calendar_astro_cleanup);
1495 if(cache == NULL) {
1496 status = U_MEMORY_ALLOCATION_ERROR;
1497 } else {
1498 *cache = new CalendarCache(32, status);
1499 if(U_FAILURE(status)) {
1500 delete *cache;
1501 *cache = NULL;
1502 }
1503 }
1504 }
1505
get(CalendarCache ** cache,int32_t key,UErrorCode & status)1506 int32_t CalendarCache::get(CalendarCache** cache, int32_t key, UErrorCode &status) {
1507 int32_t res;
1508
1509 if(U_FAILURE(status)) {
1510 return 0;
1511 }
1512 umtx_lock(&ccLock);
1513
1514 if(*cache == NULL) {
1515 createCache(cache, status);
1516 if(U_FAILURE(status)) {
1517 umtx_unlock(&ccLock);
1518 return 0;
1519 }
1520 }
1521
1522 res = uhash_igeti((*cache)->fTable, key);
1523 U_DEBUG_ASTRO_MSG(("%p: GET: [%d] == %d\n", (*cache)->fTable, key, res));
1524
1525 umtx_unlock(&ccLock);
1526 return res;
1527 }
1528
put(CalendarCache ** cache,int32_t key,int32_t value,UErrorCode & status)1529 void CalendarCache::put(CalendarCache** cache, int32_t key, int32_t value, UErrorCode &status) {
1530 if(U_FAILURE(status)) {
1531 return;
1532 }
1533 umtx_lock(&ccLock);
1534
1535 if(*cache == NULL) {
1536 createCache(cache, status);
1537 if(U_FAILURE(status)) {
1538 umtx_unlock(&ccLock);
1539 return;
1540 }
1541 }
1542
1543 uhash_iputi((*cache)->fTable, key, value, &status);
1544 U_DEBUG_ASTRO_MSG(("%p: PUT: [%d] := %d\n", (*cache)->fTable, key, value));
1545
1546 umtx_unlock(&ccLock);
1547 }
1548
CalendarCache(int32_t size,UErrorCode & status)1549 CalendarCache::CalendarCache(int32_t size, UErrorCode &status) {
1550 fTable = uhash_openSize(uhash_hashLong, uhash_compareLong, NULL, size, &status);
1551 U_DEBUG_ASTRO_MSG(("%p: Opening.\n", fTable));
1552 }
1553
~CalendarCache()1554 CalendarCache::~CalendarCache() {
1555 if(fTable != NULL) {
1556 U_DEBUG_ASTRO_MSG(("%p: Closing.\n", fTable));
1557 uhash_close(fTable);
1558 }
1559 }
1560
1561 U_NAMESPACE_END
1562
1563 #endif // !UCONFIG_NO_FORMATTING
1564