1 ;;; cal-mayan.el --- calendar functions for the Mayan calendars
3 ;; Copyright (C) 1992, 1993, 1995, 1997, 2001, 2002, 2003, 2004, 2005,
4 ;; 2006, 2007 Free Software Foundation, Inc.
6 ;; Author: Stewart M. Clamen <clamen@cs.cmu.edu>
7 ;; Edward M. Reingold <reingold@cs.uiuc.edu>
8 ;; Maintainer: Glenn Morris <rgm@gnu.org>
10 ;; Human-Keywords: Mayan calendar, Maya, calendar, diary
12 ;; This file is part of GNU Emacs.
14 ;; GNU Emacs is free software; you can redistribute it and/or modify
15 ;; it under the terms of the GNU General Public License as published by
16 ;; the Free Software Foundation; either version 3, or (at your option)
19 ;; GNU Emacs is distributed in the hope that it will be useful,
20 ;; but WITHOUT ANY WARRANTY; without even the implied warranty of
21 ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
22 ;; GNU General Public License for more details.
24 ;; You should have received a copy of the GNU General Public License
25 ;; along with GNU Emacs; see the file COPYING. If not, write to the
26 ;; Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
27 ;; Boston, MA 02110-1301, USA.
31 ;; This collection of functions implements the features of calendar.el and
32 ;; diary.el that deal with the Mayan calendar. It was written jointly by
34 ;; Stewart M. Clamen School of Computer Science
35 ;; clamen@cs.cmu.edu Carnegie Mellon University
37 ;; Pittsburgh, PA 15213
41 ;; Edward M. Reingold Department of Computer Science
42 ;; (217) 333-6733 University of Illinois at Urbana-Champaign
43 ;; reingold@cs.uiuc.edu 1304 West Springfield Avenue
44 ;; Urbana, Illinois 61801
46 ;; Technical details of the Mayan calendrical calculations can be found in
47 ;; ``Calendrical Calculations: The Millennium Edition'' by Edward M. Reingold
48 ;; and Nachum Dershowitz, Cambridge University Press (2001), and in
49 ;; ``Calendrical Calculations, Part II: Three Historical Calendars''
50 ;; by E. M. Reingold, N. Dershowitz, and S. M. Clamen,
51 ;; Software--Practice and Experience, Volume 23, Number 4 (April, 1993),
60 (defconst calendar-mayan-days-before-absolute-zero
1137142
61 "Number of days of the Mayan calendar epoch before absolute day 0.
62 This is the Goodman-Martinez-Thompson correlation used by almost all experts,
63 but some use 1137140. Using 1232041 gives you Spinden's correlation; using
64 1142840 gives you Hochleitner's correlation.")
66 (defconst calendar-mayan-haab-at-epoch
'(8 .
18)
67 "Mayan haab date at the epoch.")
69 (defconst calendar-mayan-haab-month-name-array
70 ["Pop" "Uo" "Zip" "Zotz" "Tzec" "Xul" "Yaxkin" "Mol" "Chen" "Yax"
71 "Zac" "Ceh" "Mac" "Kankin" "Muan" "Pax" "Kayab" "Cumku"])
73 (defconst calendar-mayan-tzolkin-at-epoch
'(4 .
20)
74 "Mayan tzolkin date at the epoch.")
76 (defconst calendar-mayan-tzolkin-names-array
77 ["Imix" "Ik" "Akbal" "Kan" "Chicchan" "Cimi" "Manik" "Lamat" "Muluc" "Oc"
78 "Chuen" "Eb" "Ben" "Ix" "Men" "Cib" "Caban" "Etznab" "Cauac" "Ahau"])
80 (defun calendar-mayan-long-count-from-absolute (date)
81 "Compute the Mayan long count corresponding to the absolute DATE."
82 (let ((long-count (+ date calendar-mayan-days-before-absolute-zero
)))
83 (let* ((baktun (/ long-count
144000))
84 (remainder (% long-count
144000))
85 (katun (/ remainder
7200))
86 (remainder (% remainder
7200))
87 (tun (/ remainder
360))
88 (remainder (% remainder
360))
89 (uinal (/ remainder
20))
90 (kin (% remainder
20)))
91 (list baktun katun tun uinal kin
))))
93 (defun calendar-mayan-long-count-to-string (mayan-long-count)
94 "Convert MAYAN-LONG-COUNT into traditional written form."
95 (apply 'format
(cons "%s.%s.%s.%s.%s" mayan-long-count
)))
97 (defun calendar-string-to-mayan-long-count (str)
98 "Given STR, a string of format \"%d.%d.%d.%d.%d\", return list of nums."
102 (condition-case condition
105 (let* ((start (string-match "[0-9]+" str cc
))
108 (setq datum
(read (substring str start end
)))
109 (setq rlc
(cons datum rlc
))
111 (if (not (= (length rlc
) 5)) (signal 'invalid-read-syntax nil
)))
112 (invalid-read-syntax nil
))
115 (defun calendar-mayan-haab-from-absolute (date)
116 "Convert absolute DATE into a Mayan haab date (a pair)."
117 (let* ((long-count (+ date calendar-mayan-days-before-absolute-zero
))
120 (car calendar-mayan-haab-at-epoch
)
121 (* 20 (1- (cdr calendar-mayan-haab-at-epoch
))))
123 (day (% day-of-haab
20))
124 (month (1+ (/ day-of-haab
20))))
127 (defun calendar-mayan-haab-difference (date1 date2
)
128 "Number of days from Mayan haab DATE1 to next occurrence of haab date DATE2."
129 (mod (+ (* 20 (- (cdr date2
) (cdr date1
)))
130 (- (car date2
) (car date1
)))
133 (defun calendar-mayan-haab-on-or-before (haab-date date
)
134 "Absolute date of latest HAAB-DATE on or before absolute DATE."
137 (calendar-mayan-haab-difference
138 (calendar-mayan-haab-from-absolute 0) haab-date
))
141 (defun calendar-next-haab-date (haab-date &optional noecho
)
142 "Move cursor to next instance of Mayan HAAB-DATE.
143 Echo Mayan date if NOECHO is t."
144 (interactive (list (calendar-read-mayan-haab-date)))
146 (calendar-gregorian-from-absolute
147 (calendar-mayan-haab-on-or-before
150 (calendar-absolute-from-gregorian (calendar-cursor-to-date))))))
151 (or noecho
(calendar-print-mayan-date)))
153 (defun calendar-previous-haab-date (haab-date &optional noecho
)
154 "Move cursor to previous instance of Mayan HAAB-DATE.
155 Echo Mayan date if NOECHO is t."
156 (interactive (list (calendar-read-mayan-haab-date)))
158 (calendar-gregorian-from-absolute
159 (calendar-mayan-haab-on-or-before
161 (1- (calendar-absolute-from-gregorian (calendar-cursor-to-date))))))
162 (or noecho
(calendar-print-mayan-date)))
164 (defun calendar-mayan-haab-to-string (haab)
165 "Convert Mayan haab date (a pair) into its traditional written form."
166 (let ((month (cdr haab
))
168 ;; 19th month consists of 5 special days
170 (format "%d Uayeb" day
)
173 (aref calendar-mayan-haab-month-name-array
(1- month
))))))
175 (defun calendar-mayan-tzolkin-from-absolute (date)
176 "Convert absolute DATE into a Mayan tzolkin date (a pair)."
177 (let* ((long-count (+ date calendar-mayan-days-before-absolute-zero
))
179 (+ long-count
(car calendar-mayan-tzolkin-at-epoch
))
182 (+ long-count
(cdr calendar-mayan-tzolkin-at-epoch
))
186 (defun calendar-mayan-tzolkin-difference (date1 date2
)
187 "Number of days from Mayan tzolkin DATE1 to next occurrence of tzolkin DATE2."
188 (let ((number-difference (- (car date2
) (car date1
)))
189 (name-difference (- (cdr date2
) (cdr date1
))))
190 (mod (+ number-difference
191 (* 13 (mod (* 3 (- number-difference name-difference
))
195 (defun calendar-mayan-tzolkin-on-or-before (tzolkin-date date
)
196 "Absolute date of latest TZOLKIN-DATE on or before absolute DATE."
198 (%
(- date
(calendar-mayan-tzolkin-difference
199 (calendar-mayan-tzolkin-from-absolute 0)
203 (defun calendar-next-tzolkin-date (tzolkin-date &optional noecho
)
204 "Move cursor to next instance of Mayan TZOLKIN-DATE.
205 Echo Mayan date if NOECHO is t."
206 (interactive (list (calendar-read-mayan-tzolkin-date)))
208 (calendar-gregorian-from-absolute
209 (calendar-mayan-tzolkin-on-or-before
212 (calendar-absolute-from-gregorian (calendar-cursor-to-date))))))
213 (or noecho
(calendar-print-mayan-date)))
215 (defun calendar-previous-tzolkin-date (tzolkin-date &optional noecho
)
216 "Move cursor to previous instance of Mayan TZOLKIN-DATE.
217 Echo Mayan date if NOECHO is t."
218 (interactive (list (calendar-read-mayan-tzolkin-date)))
220 (calendar-gregorian-from-absolute
221 (calendar-mayan-tzolkin-on-or-before
223 (1- (calendar-absolute-from-gregorian (calendar-cursor-to-date))))))
224 (or noecho
(calendar-print-mayan-date)))
226 (defun calendar-mayan-tzolkin-to-string (tzolkin)
227 "Convert Mayan tzolkin date (a pair) into its traditional written form."
230 (aref calendar-mayan-tzolkin-names-array
(1- (cdr tzolkin
)))))
232 (defun calendar-mayan-tzolkin-haab-on-or-before (tzolkin-date haab-date date
)
233 "Absolute date that is Mayan TZOLKIN-DATE and HAAB-DATE.
234 Latest such date on or before DATE.
235 Returns nil if such a tzolkin-haab combination is impossible."
236 (let* ((haab-difference
237 (calendar-mayan-haab-difference
238 (calendar-mayan-haab-from-absolute 0)
241 (calendar-mayan-tzolkin-difference
242 (calendar-mayan-tzolkin-from-absolute 0)
244 (difference (- tzolkin-difference haab-difference
)))
245 (if (= (% difference
5) 0)
248 (+ haab-difference
(* 365 difference
)))
252 (defun calendar-read-mayan-haab-date ()
253 "Prompt for a Mayan haab date"
254 (let* ((completion-ignore-case t
)
255 (haab-day (calendar-read
257 '(lambda (x) (and (>= x
0) (< x
20)))))
258 (haab-month-list (append calendar-mayan-haab-month-name-array
259 (and (< haab-day
5) '("Uayeb"))))
262 (completing-read "Haab uinal: "
263 (mapcar 'list haab-month-list
)
265 (calendar-make-alist haab-month-list
1) t
))))
266 (cons haab-day haab-month
)))
268 (defun calendar-read-mayan-tzolkin-date ()
269 "Prompt for a Mayan tzolkin date"
270 (let* ((completion-ignore-case t
)
271 (tzolkin-count (calendar-read
272 "Tzolkin kin (1-13): "
273 '(lambda (x) (and (> x
0) (< x
14)))))
274 (tzolkin-name-list (append calendar-mayan-tzolkin-names-array nil
))
277 (completing-read "Tzolkin uinal: "
278 (mapcar 'list tzolkin-name-list
)
280 (calendar-make-alist tzolkin-name-list
1) t
))))
281 (cons tzolkin-count tzolkin-name
)))
283 (defun calendar-next-calendar-round-date
284 (tzolkin-date haab-date
&optional noecho
)
285 "Move cursor to next instance of Mayan HAAB-DATE TZOLKIN-DATE combination.
286 Echo Mayan date if NOECHO is t."
287 (interactive (list (calendar-read-mayan-tzolkin-date)
288 (calendar-read-mayan-haab-date)))
289 (let ((date (calendar-mayan-tzolkin-haab-on-or-before
290 tzolkin-date haab-date
291 (+ 18980 (calendar-absolute-from-gregorian
292 (calendar-cursor-to-date))))))
294 (error "%s, %s does not exist in the Mayan calendar round"
295 (calendar-mayan-tzolkin-to-string tzolkin-date
)
296 (calendar-mayan-haab-to-string haab-date
))
297 (calendar-goto-date (calendar-gregorian-from-absolute date
))
298 (or noecho
(calendar-print-mayan-date)))))
300 (defun calendar-previous-calendar-round-date
301 (tzolkin-date haab-date
&optional noecho
)
302 "Move to previous instance of Mayan TZOLKIN-DATE HAAB-DATE combination.
303 Echo Mayan date if NOECHO is t."
304 (interactive (list (calendar-read-mayan-tzolkin-date)
305 (calendar-read-mayan-haab-date)))
306 (let ((date (calendar-mayan-tzolkin-haab-on-or-before
307 tzolkin-date haab-date
308 (1- (calendar-absolute-from-gregorian
309 (calendar-cursor-to-date))))))
311 (error "%s, %s does not exist in the Mayan calendar round"
312 (calendar-mayan-tzolkin-to-string tzolkin-date
)
313 (calendar-mayan-haab-to-string haab-date
))
314 (calendar-goto-date (calendar-gregorian-from-absolute date
))
315 (or noecho
(calendar-print-mayan-date)))))
317 (defun calendar-absolute-from-mayan-long-count (c)
318 "Compute the absolute date corresponding to the Mayan Long Count C.
319 Long count is a list (baktun katun tun uinal kin)"
320 (+ (* (nth 0 c
) 144000) ; baktun
321 (* (nth 1 c
) 7200) ; katun
322 (* (nth 2 c
) 360) ; tun
323 (* (nth 3 c
) 20) ; uinal
324 (nth 4 c
) ; kin (days)
325 (- ; days before absolute date 0
326 calendar-mayan-days-before-absolute-zero
)))
328 (defun calendar-mayan-date-string (&optional date
)
329 "String of Mayan date of Gregorian DATE.
330 Defaults to today's date if DATE is not given."
331 (let* ((d (calendar-absolute-from-gregorian
332 (or date
(calendar-current-date))))
333 (tzolkin (calendar-mayan-tzolkin-from-absolute d
))
334 (haab (calendar-mayan-haab-from-absolute d
))
335 (long-count (calendar-mayan-long-count-from-absolute d
)))
336 (format "Long count = %s; tzolkin = %s; haab = %s"
337 (calendar-mayan-long-count-to-string long-count
)
338 (calendar-mayan-tzolkin-to-string tzolkin
)
339 (calendar-mayan-haab-to-string haab
))))
341 (defun calendar-print-mayan-date ()
342 "Show the Mayan long count, tzolkin, and haab equivalents of date."
344 (message "Mayan date: %s"
345 (calendar-mayan-date-string (calendar-cursor-to-date t
))))
347 (defun calendar-goto-mayan-long-count-date (date &optional noecho
)
348 "Move cursor to Mayan long count DATE. Echo Mayan date unless NOECHO is t."
353 (calendar-string-to-mayan-long-count
354 (read-string "Mayan long count (baktun.katun.tun.uinal.kin): "
355 (calendar-mayan-long-count-to-string
356 (calendar-mayan-long-count-from-absolute
357 (calendar-absolute-from-gregorian
358 (calendar-current-date))))))))
359 (if (calendar-mayan-long-count-common-era datum
)
363 (calendar-gregorian-from-absolute
364 (calendar-absolute-from-mayan-long-count date
)))
365 (or noecho
(calendar-print-mayan-date)))
367 (defun calendar-mayan-long-count-common-era (lc)
368 "T if long count represents date in the Common Era."
369 (let ((base (calendar-mayan-long-count-from-absolute 1)))
370 (while (and (not (null base
)) (= (car lc
) (car base
)))
373 (or (null lc
) (> (car lc
) (car base
)))))
375 (defun diary-mayan-date ()
376 "Show the Mayan long count, haab, and tzolkin dates as a diary entry."
377 (format "Mayan date: %s" (calendar-mayan-date-string date
)))
381 ;;; arch-tag: 54f35144-cd0f-4873-935a-a60129de07df
382 ;;; cal-mayan.el ends here