;;; Commentary:
;; This collection of functions implements the features of calendar.el,
-;; diary.el, and holidays.el that deal with the Chinese calendar. It was
-;; written by
-
+;; diary.el, and holidays.el that deal with the Chinese calendar. The rules
+;; used for the Chinese calendar are those of Baolin Liu (see L. E. Doggett's
+;; article "Calendars" in the Explanatory Supplement to the Astronomical
+;; Almanac, second edition, 1992) for the calendar as revised at the beginning
+;; of the Qing dynasty in 1644. Liu's rules produce a calendar for 2033 which
+;; is not accepted by all authorities. Furthermore, the nature of the
+;; astronomical calculations is such that precise calculations cannot be made
+;; without great expense in time, so that the calendars produced may not agree
+;; perfectly with published tables--but no two pairs of published tables agree
+;; perfectly either!
+
+;; Comments, corrections, and improvements should be sent to
;; Edward M. Reingold Department of Computer Science
;; (217) 333-6733 University of Illinois at Urbana-Champaign
;; reingold@cs.uiuc.edu 1304 West Springfield Avenue
"Absolute date of first new Zodiac sign on or after absolute date d.
The Zodiac signs begin when the sun's longitude is a multiple of 30 degrees."
(let* ((year (extract-calendar-year
- (calendar-gregorian-from-absolute
- (floor (calendar-absolute-from-astro d)))))
+ (calendar-gregorian-from-absolute d)))
(calendar-time-zone (eval chinese-calendar-time-zone))
(calendar-daylight-time-offset
chinese-calendar-daylight-time-offset)
(lunar-new-moon-on-or-after
(calendar-astro-from-absolute d))))))
+(defvar chinese-year-cache
+ '((1989 (12 . 726110) (1 . 726139) (2 . 726169) (3 . 726198) (4 . 726227)
+ (5 . 726257) (6 . 726286) (7 . 726316) (8 . 726345) (9 . 726375)
+ (10 . 726404) (11 . 726434))
+ (1990 (12 . 726464) (1 . 726494) (2 . 726523) (3 . 726553) (4 . 726582)
+ (5 . 726611) (5.5 . 726641) (6 . 726670) (7 . 726699) (8 . 726729)
+ (9 . 726758) (10 . 726788) (11 . 726818))
+ (1991 (12 . 726848) (1 . 726878) (2 . 726907) (3 . 726937) (4 . 726966)
+ (5 . 726995) (6 . 727025) (7 . 727054) (8 . 727083) (9 . 727113)
+ (10 . 727142) (11 . 727172))
+ (1992 (12 . 727202) (1 . 727232) (2 . 727261) (3 . 727291) (4 . 727321)
+ (5 . 727350) (6 . 727379) (7 . 727409) (8 . 727438) (9 . 727467)
+ (10 . 727497) (11 . 727526))
+ (1993 (12 . 727556) (1 . 727586) (2 . 727615) (3 . 727645) (3.5 . 727675)
+ (4 . 727704) (5 . 727734) (6 . 727763) (7 . 727793) (8 . 727822)
+ (9 . 727851) (10 . 727881) (11 . 727910))
+ (1994 (12 . 727940) (1 . 727969) (2 . 727999) (3 . 728029) (4 . 728059)
+ (5 . 728088) (6 . 728118) (7 . 728147) (8 . 728177) (9 . 728206)
+ (10 . 728235) (11 . 728265))
+ (1995 (12 . 728294) (1 . 728324) (2 . 728353) (3 . 728383) (4 . 728413)
+ (5 . 728442) (6 . 728472) (7 . 728501) (8 . 728531) (8.5 . 728561)
+ (9 . 728590) (10 . 728619) (11 . 728649))
+ (1996 (12 . 728678) (1 . 728708) (2 . 728737) (3 . 728767) (4 . 728796)
+ (5 . 728826) (6 . 728856) (7 . 728885) (8 . 728915) (9 . 728944)
+ (10 . 728974) (11 . 729004))
+ (1997 (12 . 729033) (1 . 729062) (2 . 729092) (3 . 729121) (4 . 729151)
+ (5 . 729180) (6 . 729210) (7 . 729239) (8 . 729269) (9 . 729299)
+ (10 . 729328) (11 . 729358))
+ (1998 (12 . 729388) (1 . 729417) (2 . 729447) (3 . 729476) (4 . 729505)
+ (5 . 729535) (5.5 . 729564) (6 . 729593) (7 . 729623) (8 . 729653)
+ (9 . 729682) (10 . 729712) (11 . 729742))
+ (1999 (12 . 729771) (1 . 729801) (2 . 729831) (3 . 729860) (4 . 729889)
+ (5 . 729919) (6 . 729948) (7 . 729977) (8 . 730007) (9 . 730036)
+ (10 . 730066) (11 . 730096))
+ (2000 (12 . 730126) (1 . 730155) (2 . 730185) (3 . 730215) (4 . 730244)
+ (5 . 730273) (6 . 730303) (7 . 730332) (8 . 730361) (9 . 730391)
+ (10 . 730420) (11 . 730450)))
+ "An assoc list of Chinese year structures as determined by `chinese-year'.
+
+Values are computed as needed, but to save time, the initial value consists
+of the precomputed years 1989-2000. The code works just as well with this
+set to nil initially (which is how the value for 1989-2000 was computed).")
+
+(defun chinese-year (y)
+ "The structure of the Chinese year for Gregorian year Y.
+The result is a list of pairs (i . d), where month i begins on absolute date d,
+of the Chinese months from the Chinese month following the solstice in
+Gregorian year Y-1 to the Chinese month of the solstice of Gregorian year Y.
+
+The list is cached for further use."
+ (let ((list (cdr (assoc y chinese-year-cache))))
+ (if (not list)
+ (progn
+ (setq list (compute-chinese-year y))
+ (setq chinese-year-cache
+ (append chinese-year-cache (list (cons y list))))))
+ list))
+
+(defun number-chinese-months (list start &optional no-leap-months)
+ "Assign month numbers to the lunar months in LIST, starting with START.
+
+If optional parameter NO-LEAP-MONTHS is true, just number the months
+sequentially, ignoring the usual leap month rule.
+
+First month of list will never be a leap month, nor will the last.
+
+Numbers are assigned sequentially mod 12 (but using 12 instead of 0)."
+ (if list
+ (if no-leap-months
+ (cons (cons (calendar-mod start 12) (car list))
+ (number-chinese-months (cdr list) (1+ start) t))
+ (cons
+ ;; first month
+ (cons (calendar-mod start 12) (car list))
+ ;; remaining months
+ (if (and (cdr (cdr list));; at least two more months...
+ ;; ... and next one is a leap month
+ (<= (car (cdr (cdr list)))
+ (chinese-zodiac-sign-on-or-after (car (cdr list)))))
+ (cons (cons (+ (calendar-mod start 12) 0.5) (car (cdr list)))
+ (number-chinese-months (cdr (cdr list)) (1+ start) t))
+ ;; Otherwise, just number the months
+ (number-chinese-months (cdr list) (1+ start)))))))
+
+(defun chinese-month-list (start end)
+ "List of starting dates of Chinese months from START to END."
+ (if (<= start end)
+ (let ((new-moon (chinese-new-moon-on-or-after start)))
+ (if (<= new-moon end)
+ (append (list new-moon)
+ (chinese-month-list (1+ new-moon) end))))))
+
+(defun chinese-leap-months (list low high)
+ "Return list of leap months in LIST with indices in range LOW to HIGH.
+
+A leap month has a non-integer index."
+ (if list
+ (let ((index (car (car list))))
+ (if (and (/= index (floor index))
+ (<= low index)
+ (<= index high))
+ (cons index (chinese-leap-months (cdr list) low high))
+ (chinese-leap-months (cdr list) low high)))))
+
+(defun compute-chinese-year (y)
+ "Compute the structure of the Chinese year for Gregorian year Y.
+The result is a list of pairs (i . d), where month i begins on absolute date d,
+of the Chinese months from the Chinese month following the solstice in
+Gregorian year Y-1 to the Chinese month of the solstice of Gregorian year Y."
+ (let* ((next-solstice (chinese-zodiac-sign-on-or-after
+ (calendar-absolute-from-gregorian
+ (list 12 15 y))))
+ (list (chinese-month-list (1+ (chinese-zodiac-sign-on-or-after
+ (calendar-absolute-from-gregorian
+ (list 12 15 (1- y)))))
+ next-solstice)))
+ (if (= (length list) 12)
+ ;; No room for a leap month, just number them 12, 1, 2, ..., 11
+ (number-chinese-months list 0 t)
+ (let* ((had-leap-month (chinese-leap-months (chinese-year (1- y)) 1 10))
+ (numbered-list)
+ (next-sign;; On or after first month on list
+ (chinese-zodiac-sign-on-or-after (car list))))
+ ;; Now we can assign numbers to the list for y
+ ;; The first month or two are special
+ (if (and (<= (car list) next-sign) (< next-sign (car (cdr list))))
+ (progn;; First month on list is not a leap month
+ (setq numbered-list (list (cons 12 (car list))))
+ (setq list (cdr list))
+ (setq next-sign (chinese-zodiac-sign-on-or-after (car list))))
+ ;; First month on list might be a leap month...
+ (if (not had-leap-month);; ... it is a leap month
+ (progn;; First month on list is a leap month, so second is not
+ (setq numbered-list (list (cons 11.5 (car list))
+ (cons 12 (car (cdr list)))))
+ (setq list (cdr (cdr list)))
+ (setq had-leap-month t))))
+ (if (and (>= next-sign (car (cdr list)))
+ (not had-leap-month))
+ (progn;; Second month on list is a leap month
+ (setq numbered-list
+ (append numbered-list (list (cons 12.5 (car list)))))
+ (setq list (cdr list))))
+ ;; At this point we have a list of new moons for months 1 to 11 for y.
+ ;; We need to see which are leap months.
+ (if (= (length list) 11)
+ ;; There can be no leap months, just number them 1..11
+ (append numbered-list (number-chinese-months list 1 t))
+ ;; There is a leap month, but it can't be the first one because that
+ ;; would be 12.5 which we already considered. It also can't be the
+ ;; last one because that has the solstice in it.
+ (append numbered-list (number-chinese-months list 1)))))))
+
(defun calendar-absolute-from-chinese (date)
"The number of days elapsed between the Gregorian date 12/31/1 BC and DATE.
The Gregorian date Sunday, December 31, 1 BC is imaginary."
(month (car (cdr (cdr date))))
(day (car (cdr (cdr (cdr date)))))
(g-year (+ (* (1- cycle) 60);; years in prior cycles
- (1- year);; prior years this cycle
- -2636));; years before absolute date 0
- (new-year (chinese-new-year g-year))
- (current-month new-year)
- (current-month-number 1)
- (next-month (chinese-new-moon-on-or-after (1+ new-year)))
- (next-sign (chinese-zodiac-sign-on-or-after
- (1+ (chinese-zodiac-sign-on-or-after current-month))))
- (had-leap-month nil))
- (while (< current-month-number month)
- ;; current-month < next-month <= next-sign
- (setq current-month next-month)
- (setq next-month (chinese-new-moon-on-or-after (1+ current-month)))
- (if (and (<= next-month next-sign) (not had-leap-month))
- (progn;; leap month
- (setq current-month-number (+ current-month-number 0.5))
- (setq had-leap-month t))
- (setq current-month-number (floor (1+ current-month-number)))
- (setq next-sign (chinese-zodiac-sign-on-or-after (1+ next-sign)))))
- (+ current-month (1- day))))
+ (1- year) ;; prior years this cycle
+ -2636))) ;; years before absolute date 0
+ (+ (1- day);; prior days this month
+ (cdr ;; absolute date of start of this month
+ (assoc month (append (memq (assoc 1 (chinese-year g-year))
+ (chinese-year g-year))
+ (chinese-year (1+ g-year))))))))
(defun calendar-chinese-from-absolute (date)
"Compute Chinese date (cycle year month day) corresponding to absolute DATE.
The absolute date is the number of days elapsed since the (imaginary)
Gregorian date Sunday, December 31, 1 BC."
- (let* ((greg-date (calendar-gregorian-from-absolute date))
- (greg-year (1- (extract-calendar-year greg-date)))
- (greg-year
- (+ greg-year
- (calendar-sum y greg-year
- (>= date (chinese-new-year (1+ y))) 1)) )
- (chinese-year (+ greg-year 2697))
- (cycle (/ (1- chinese-year) 60)) ;; previous cycles
- (year (calendar-mod chinese-year 60));; years this cycle
- (current-month (chinese-new-year greg-year))
- (month 1)
- (next-month (chinese-new-moon-on-or-after (1+ current-month)))
- (next-sign (chinese-zodiac-sign-on-or-after
- (1+ (chinese-zodiac-sign-on-or-after current-month))))
- (had-leap-month nil))
- (while (<= next-month date)
- ;; current-month < next-month <= next-sign
- (setq current-month next-month)
- (setq next-month (chinese-new-moon-on-or-after (1+ current-month)))
- (if (and (<= next-month next-sign) (not had-leap-month))
- (progn;; leap month
- (setq month (+ month 0.5))
- (setq had-leap-month t))
- (setq month (floor (1+ month)))
- (setq next-sign (chinese-zodiac-sign-on-or-after (1+ next-sign)))))
- (list cycle year month (1+ (- date current-month)))))
-
-(defun chinese-new-year (year)
- "The absolute date of Chinese New Year in Gregorian YEAR."
- (let* ((last-solstice (chinese-zodiac-sign-on-or-after
- (calendar-absolute-from-gregorian
- (list 12 15 (1- year)))))
- (twelfth-new-moon;; twelfth month of previous year
- (chinese-new-moon-on-or-after (1+ last-solstice)))
- (thirteenth-new-moon;; maybe leap month, maybe New Year
- (chinese-new-moon-on-or-after (1+ twelfth-new-moon)))
- (fourteenth-new-moon;; maybe New Year, maybe second month
- (chinese-new-moon-on-or-after (1+ thirteenth-new-moon)))
- (next-solstice (chinese-zodiac-sign-on-or-after
- (calendar-absolute-from-gregorian (list 12 15 year))))
- (new-moons (+ 3 (calendar-sum m 0
- (< (chinese-new-moon-on-or-after
- (+ fourteenth-new-moon (* 29 m)))
- next-solstice)
- 1))))
- (if (and (= new-moons 14)
- (< (chinese-zodiac-sign-on-or-after
- (calendar-absolute-from-gregorian (list 2 15 year)))
- thirteenth-new-moon)
- (<= fourteenth-new-moon
- (chinese-zodiac-sign-on-or-after
- (calendar-absolute-from-gregorian (list 3 15 year)))))
- fourteeth-new-moon
- thirteenth-new-moon)))
+ (let* ((g-year (extract-calendar-year
+ (calendar-gregorian-from-absolute date)))
+ (chinese-year (+ g-year 2695))
+ (list (append (chinese-year (1- g-year))
+ (chinese-year g-year)
+ (chinese-year (1+ g-year)))))
+ (while (<= (cdr (car (cdr list))) date)
+ (if (= 1 (car (car (cdr list))))
+ (setq chinese-year (1+ chinese-year)))
+ (setq list (cdr list)))
+ (list (/ (1- chinese-year) 60)
+ (calendar-mod chinese-year 60)
+ (car (car list))
+ (1+ (- date (cdr (car list)))))))
(defun holiday-chinese-new-year ()
"Date of Chinese New Year."
(if (< m 5)
(let ((chinese-new-year
(calendar-gregorian-from-absolute
- (chinese-new-year y))))
+ (cdr (assoc 1 (chinese-year y))))))
(if (calendar-date-is-visible-p chinese-new-year)
(list (list chinese-new-year
(format "Chinese New Year (%s-%s)"
(this-month (calendar-absolute-from-chinese
(list cycle year month 1)))
(next-month (calendar-absolute-from-chinese
- (list cycle year (1+ month) 1)))
- (month (floor month))
- (m-cycle (% (+ (* year 5) month) 60)))
+ (list cycle year (1+ (floor month)) 1)))
+ (m-cycle (% (+ (* year 5) (floor month)) 60)))
(format "Cycle %s, year %s (%s-%s), %smonth %s, day %s (%s-%s)"
cycle
year
(if (< 30 (- next-month this-month))
"first "
""))
- month
+ (floor month)
day
(aref chinese-calendar-celestial-stem (% (+ a-date 4) 10))
(aref chinese-calendar-terrestrial-branch (% (+ a-date 2) 12)))))
(calendar-absolute-from-gregorian
(calendar-current-date))))
(cycle (calendar-read
- "Cycle number (>44): "
+ "Chinese calendar cycle number (>44): "
'(lambda (x) (> x 44))
(int-to-string (car c))))
(year (calendar-read
- "Year in cycle (1..60): "
+ "Year in Chinese cycle (1..60): "
'(lambda (x) (and (<= 1 x) (<= x 60)))
(int-to-string (car (cdr c)))))
- (month (read-minibuffer "Month: "))
- (day (read-minibuffer "Day: ")))
+ (month-list (make-chinese-month-assoc-list
+ (chinese-months cycle year)))
+ (month (cdr (assoc
+ (completing-read "Chinese calendar month: "
+ month-list nil t)
+ month-list)))
+ (last (if (= month
+ (car (cdr (cdr
+ (calendar-chinese-from-absolute
+ (+ 29
+ (calendar-absolute-from-chinese
+ (list cycle year month 1))))))))
+ 30
+ 29))
+ (day (calendar-read
+ (format "Chinese calendar day (1-%d): " last)
+ '(lambda (x) (and (<= 1 x) (<= x last))))))
(list (list cycle year month day))))
(calendar-goto-date (calendar-gregorian-from-absolute
(calendar-absolute-from-chinese date)))
(or noecho (calendar-print-chinese-date)))
+(defun chinese-months (c y)
+ "A list of the months in cycle C, year Y of the Chinese calendar."
+ (let* ((l (memq 1 (append
+ (mapcar '(lambda (x)
+ (car x))
+ (chinese-year (extract-calendar-year
+ (calendar-gregorian-from-absolute
+ (calendar-absolute-from-chinese
+ (list c y 1 1))))))
+ (mapcar '(lambda (x)
+ (if (> (car x) 11) (car x)))
+ (chinese-year (extract-calendar-year
+ (calendar-gregorian-from-absolute
+ (calendar-absolute-from-chinese
+ (list (if (= y 60) (1+ c) c)
+ (if (= y 60) 1 y)
+ 1 1))))))))))
+ l))
+
+(defun make-chinese-month-assoc-list (l)
+ "Make list of months L into an assoc list."
+ (if (and l (car l))
+ (if (and (cdr l) (car (cdr l)))
+ (if (= (car l) (floor (car (cdr l))))
+ (append
+ (list (cons (format "%s (first)" (car l)) (car l))
+ (cons (format "%s (second)" (car l)) (car (cdr l))))
+ (make-chinese-month-assoc-list (cdr (cdr l))))
+ (append
+ (list (cons (int-to-string (car l)) (car l)))
+ (make-chinese-month-assoc-list (cdr l))))
+ (list (cons (int-to-string (car l)) (car l))))))
+
(defun diary-chinese-date ()
"Chinese calendar equivalent of date diary entry."
(format "Chinese date: %s" (calendar-chinese-date-string date)))
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