;;; cal-chinese.el --- calendar functions for the Chinese calendar. ;; Copyright (C) 1995 Free Software Foundation, Inc. ;; Author: Edward M. Reingold ;; Keywords: calendar ;; Human-Keywords: Chinese calendar, calendar, holidays, diary ;; This file is part of GNU Emacs. ;; GNU Emacs is free software; you can redistribute it and/or modify ;; it under the terms of the GNU General Public License as published by ;; the Free Software Foundation; either version 2, or (at your option) ;; any later version. ;; GNU Emacs is distributed in the hope that it will be useful, ;; but WITHOUT ANY WARRANTY; without even the implied warranty of ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the ;; GNU General Public License for more details. ;; You should have received a copy of the GNU General Public License ;; along with GNU Emacs; see the file COPYING. If not, write to ;; the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA. ;;; Commentary: ;; This collection of functions implements the features of calendar.el, ;; 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. 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! Liu's ;; rules produce a calendar for 2033 which is not accepted by all authorities. ;; The date of Chinese New Year is correct from 1644-2051. ;; 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 ;; Urbana, Illinois 61801 ;;; Code: (require 'lunar) (defvar chinese-calendar-terrestrial-branch ["Zi" "Chou" "Yin" "Mao" "Chen" "Si" "Wu" "Wei" "Shen" "You" "Xu" "Hai"]) (defvar chinese-calendar-celestial-stem ["Jia" "Yi" "Bing" "Ding" "Wu" "Ji" "Geng" "Xin" "Ren" "Gui"]) (defvar chinese-calendar-time-zone '(if (< year 1928) (+ 465 (/ 40.0 60.0)) 480) "*Number of minutes difference between local standard time for Chinese calendar and Coordinated Universal (Greenwich) Time. Default is for Beijing. This is an expression in `year' since it changed at 1928-01-01 00:00:00 from UT+7:45:40 to UT+8.") (defvar chinese-calendar-location-name "Beijing" "*Name of location used for calculation of Chinese calendar.") (defvar chinese-calendar-daylight-time-offset 60 "*Number of minutes difference between daylight savings and standard time for Chinese calendar.") (defvar chinese-calendar-standard-time-zone-name '(if (< year 1928) "PMT" "CST") "*Abbreviated name of standard time zone used for Chinese calendar.") (defvar chinese-calendar-daylight-time-zone-name "CDT" "*Abbreviated name of daylight-savings time zone used for Chinese calendar.") (defvar chinese-calendar-daylight-savings-starts '(cond ((< 1986 year) (calendar-nth-named-day 1 0 4 year 10)) ((= 1986 year) '(5 4 1986)) (t nil)) "*Sexp giving the date on which daylight savings time starts for Chinese calendar. See documentation of `calendar-daylight-savings-starts'.") (defvar chinese-calendar-daylight-savings-ends '(if (<= 1986 year) (calendar-nth-named-day 1 0 9 year 11)) "*Sexp giving the date on which daylight savings time ends for Chinese calendar. See documentation of `calendar-daylight-savings-ends'.") (defvar chinese-calendar-daylight-savings-starts-time 0 "*Number of minutes after midnight that daylight savings time starts for Chinese calendar.") (defvar chinese-calendar-daylight-savings-ends-time 0 "*Number of minutes after midnight that daylight savings time ends for Chinese calendar.") (defun chinese-zodiac-sign-on-or-after (d) "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 d))) (calendar-time-zone (eval chinese-calendar-time-zone)) (calendar-daylight-time-offset chinese-calendar-daylight-time-offset) (calendar-standard-time-zone-name chinese-calendar-standard-time-zone-name) (calendar-daylight-time-zone-name chinese-calendar-daylight-time-zone-name) (calendar-calendar-daylight-savings-starts chinese-calendar-daylight-savings-starts) (calendar-daylight-savings-ends chinese-calendar-daylight-savings-ends) (calendar-daylight-savings-starts-time chinese-calendar-daylight-savings-starts-time) (calendar-daylight-savings-ends-time chinese-calendar-daylight-savings-ends-time)) (floor (calendar-absolute-from-astro (solar-date-next-longitude (calendar-astro-from-absolute d) 30))))) (defun chinese-new-moon-on-or-after (d) "Absolute date of first new moon on or after absolute date d." (let* ((year (extract-calendar-year (calendar-gregorian-from-absolute d))) (calendar-time-zone (eval chinese-calendar-time-zone)) (calendar-daylight-time-offset chinese-calendar-daylight-time-offset) (calendar-standard-time-zone-name chinese-calendar-standard-time-zone-name) (calendar-daylight-time-zone-name chinese-calendar-daylight-time-zone-name) (calendar-calendar-daylight-savings-starts chinese-calendar-daylight-savings-starts) (calendar-daylight-savings-ends chinese-calendar-daylight-savings-ends) (calendar-daylight-savings-starts-time chinese-calendar-daylight-savings-starts-time) (calendar-daylight-savings-ends-time chinese-calendar-daylight-savings-ends-time)) (floor (calendar-absolute-from-astro (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) "Assign month numbers to the lunar months in LIST, starting with START. Numbers are assigned sequentially, START, START+1, ..., 11, with half numbers used for leap months. 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." (if list (if (zerop (- 12 start (length list))) ;; List is too short for a leap month (cons (cons start (car list)) (number-chinese-months (cdr list) (1+ start))) (cons ;; First month (cons start (car list)) ;; Remaining months (if (and (cdr (cdr list));; at least two more months... (<= (car (cdr (cdr list))) (chinese-zodiac-sign-on-or-after (car (cdr list))))) ;; Next month is a leap month (cons (cons (+ start 0.5) (car (cdr list))) (number-chinese-months (cdr (cdr list)) (1+ start))) ;; Next month is not a leap month (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 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)) (next-sign (chinese-zodiac-sign-on-or-after (car list)))) (if (= (length list) 12) ;; No room for a leap month, just number them 12, 1, 2, ..., 11 (cons (cons 12 (car list)) (number-chinese-months (cdr list) 1)) ;; Now we can assign numbers to the list for y ;; The first month or two are special (if (or (> (car list) next-sign) (>= next-sign (car (cdr list)))) ;; First month on list is a leap month, second is not (append (list (cons 11.5 (car list)) (cons 12 (car (cdr list)))) (number-chinese-months (cdr (cdr list)) 1)) ;; First month on list is not a leap month (append (list (cons 12 (car list))) (if (>= (chinese-zodiac-sign-on-or-after (car (cdr list))) (car (cdr (cdr list)))) ;; Second month on list is a leap month (list (cons 12.5 (car (cdr list))) (number-chinese-months (cdr (cdr list)) 1)) ;; Second month on list is not a leap month (number-chinese-months (cdr 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." (let* ((cycle (car date)) (year (car (cdr date))) (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 (+ (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* ((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." (let ((m displayed-month) (y displayed-year)) (increment-calendar-month m y 1) (if (< m 5) (let ((chinese-new-year (calendar-gregorian-from-absolute (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)" (aref chinese-calendar-celestial-stem (% (+ y 6) 10)) (aref chinese-calendar-terrestrial-branch (% (+ y 8) 12)))))))))) (defun calendar-chinese-date-string (&optional date) "String of Chinese date of Gregorian DATE. Defaults to today's date if DATE is not given." (let* ((a-date (calendar-absolute-from-gregorian (or date (calendar-current-date)))) (c-date (calendar-chinese-from-absolute a-date)) (cycle (car c-date)) (year (car (cdr c-date))) (month (car (cdr (cdr c-date)))) (day (car (cdr (cdr (cdr c-date))))) (this-month (calendar-absolute-from-chinese (list cycle year month 1))) (next-month (calendar-absolute-from-chinese (list (if (= year 60) (1+ cycle) cycle) (if (= (floor month) 12) (1+ year) year) (calendar-mod (1+ (floor month)) 12) 1))) (m-cycle (% (+ (* year 5) (floor month)) 60))) (format "Cycle %s, year %s (%s-%s), %smonth %s, day %s (%s-%s)" cycle year (aref chinese-calendar-celestial-stem (% (+ year 9) 10)) (aref chinese-calendar-terrestrial-branch (% (+ year 11) 12)) (if (not (integerp month)) "second " (if (< 30 (- next-month this-month)) "first " "")) (floor month) day (aref chinese-calendar-celestial-stem (% (+ a-date 4) 10)) (aref chinese-calendar-terrestrial-branch (% (+ a-date 2) 12))))) (defun calendar-print-chinese-date () "Show the Chinese date equivalents of date." (interactive) (message "Computing Chinese date...") (message "Chinese date: %s" (calendar-chinese-date-string (calendar-cursor-to-date t)))) (defun calendar-goto-chinese-date (date &optional noecho) "Move cursor to Chinese date DATE. Echo Chinese date unless NOECHO is t." (interactive (let* ((c (calendar-chinese-from-absolute (calendar-absolute-from-gregorian (calendar-current-date)))) (cycle (calendar-read "Chinese calendar cycle number (>44): " '(lambda (x) (> x 44)) (int-to-string (car c)))) (year (calendar-read "Year in Chinese cycle (1..60): " '(lambda (x) (and (<= 1 x) (<= x 60))) (int-to-string (car (cdr c))))) (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))) (provide 'cal-chinese) ;;; cal-chinese ends here