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 2, 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 ;; Comments, improvements, and bug reports should be sent to Reingold.
48 ;; Technical details of the Mayan calendrical calculations can be found in
49 ;; ``Calendrical Calculations: The Millennium Edition'' by Edward M. Reingold
50 ;; and Nachum Dershowitz, Cambridge University Press (2001), and in
51 ;; ``Calendrical Calculations, Part II: Three Historical Calendars''
52 ;; by E. M. Reingold, N. Dershowitz, and S. M. Clamen,
53 ;; Software--Practice and Experience, Volume 23, Number 4 (April, 1993),
62 (defconst calendar-mayan-days-before-absolute-zero
1137142
63 "Number of days of the Mayan calendar epoch before absolute day 0.
64 This is the Goodman-Martinez-Thompson correlation used by almost all experts,
65 but some use 1137140. Using 1232041 gives you Spinden's correlation; using
66 1142840 gives you Hochleitner's correlation.")
68 (defconst calendar-mayan-haab-at-epoch
'(8 .
18)
69 "Mayan haab date at the epoch.")
71 (defconst calendar-mayan-haab-month-name-array
72 ["Pop" "Uo" "Zip" "Zotz" "Tzec" "Xul" "Yaxkin" "Mol" "Chen" "Yax"
73 "Zac" "Ceh" "Mac" "Kankin" "Muan" "Pax" "Kayab" "Cumku"])
75 (defconst calendar-mayan-tzolkin-at-epoch
'(4 .
20)
76 "Mayan tzolkin date at the epoch.")
78 (defconst calendar-mayan-tzolkin-names-array
79 ["Imix" "Ik" "Akbal" "Kan" "Chicchan" "Cimi" "Manik" "Lamat" "Muluc" "Oc"
80 "Chuen" "Eb" "Ben" "Ix" "Men" "Cib" "Caban" "Etznab" "Cauac" "Ahau"])
82 (defun calendar-mayan-long-count-from-absolute (date)
83 "Compute the Mayan long count corresponding to the absolute DATE."
84 (let ((long-count (+ date calendar-mayan-days-before-absolute-zero
)))
85 (let* ((baktun (/ long-count
144000))
86 (remainder (% long-count
144000))
87 (katun (/ remainder
7200))
88 (remainder (% remainder
7200))
89 (tun (/ remainder
360))
90 (remainder (% remainder
360))
91 (uinal (/ remainder
20))
92 (kin (% remainder
20)))
93 (list baktun katun tun uinal kin
))))
95 (defun calendar-mayan-long-count-to-string (mayan-long-count)
96 "Convert MAYAN-LONG-COUNT into traditional written form."
97 (apply 'format
(cons "%s.%s.%s.%s.%s" mayan-long-count
)))
99 (defun calendar-string-to-mayan-long-count (str)
100 "Given STR, a string of format \"%d.%d.%d.%d.%d\", return list of nums."
104 (condition-case condition
107 (let* ((start (string-match "[0-9]+" str cc
))
110 (setq datum
(read (substring str start end
)))
111 (setq rlc
(cons datum rlc
))
113 (if (not (= (length rlc
) 5)) (signal 'invalid-read-syntax nil
)))
114 (invalid-read-syntax nil
))
117 (defun calendar-mayan-haab-from-absolute (date)
118 "Convert absolute DATE into a Mayan haab date (a pair)."
119 (let* ((long-count (+ date calendar-mayan-days-before-absolute-zero
))
122 (car calendar-mayan-haab-at-epoch
)
123 (* 20 (1- (cdr calendar-mayan-haab-at-epoch
))))
125 (day (% day-of-haab
20))
126 (month (1+ (/ day-of-haab
20))))
129 (defun calendar-mayan-haab-difference (date1 date2
)
130 "Number of days from Mayan haab DATE1 to next occurrence of haab date DATE2."
131 (mod (+ (* 20 (- (cdr date2
) (cdr date1
)))
132 (- (car date2
) (car date1
)))
135 (defun calendar-mayan-haab-on-or-before (haab-date date
)
136 "Absolute date of latest HAAB-DATE on or before absolute DATE."
139 (calendar-mayan-haab-difference
140 (calendar-mayan-haab-from-absolute 0) haab-date
))
143 (defun calendar-next-haab-date (haab-date &optional noecho
)
144 "Move cursor to next instance of Mayan HAAB-DATE.
145 Echo Mayan date if NOECHO is t."
146 (interactive (list (calendar-read-mayan-haab-date)))
148 (calendar-gregorian-from-absolute
149 (calendar-mayan-haab-on-or-before
152 (calendar-absolute-from-gregorian (calendar-cursor-to-date))))))
153 (or noecho
(calendar-print-mayan-date)))
155 (defun calendar-previous-haab-date (haab-date &optional noecho
)
156 "Move cursor to previous instance of Mayan HAAB-DATE.
157 Echo Mayan date if NOECHO is t."
158 (interactive (list (calendar-read-mayan-haab-date)))
160 (calendar-gregorian-from-absolute
161 (calendar-mayan-haab-on-or-before
163 (1- (calendar-absolute-from-gregorian (calendar-cursor-to-date))))))
164 (or noecho
(calendar-print-mayan-date)))
166 (defun calendar-mayan-haab-to-string (haab)
167 "Convert Mayan haab date (a pair) into its traditional written form."
168 (let ((month (cdr haab
))
170 ;; 19th month consists of 5 special days
172 (format "%d Uayeb" day
)
175 (aref calendar-mayan-haab-month-name-array
(1- month
))))))
177 (defun calendar-mayan-tzolkin-from-absolute (date)
178 "Convert absolute DATE into a Mayan tzolkin date (a pair)."
179 (let* ((long-count (+ date calendar-mayan-days-before-absolute-zero
))
181 (+ long-count
(car calendar-mayan-tzolkin-at-epoch
))
184 (+ long-count
(cdr calendar-mayan-tzolkin-at-epoch
))
188 (defun calendar-mayan-tzolkin-difference (date1 date2
)
189 "Number of days from Mayan tzolkin DATE1 to next occurrence of tzolkin DATE2."
190 (let ((number-difference (- (car date2
) (car date1
)))
191 (name-difference (- (cdr date2
) (cdr date1
))))
192 (mod (+ number-difference
193 (* 13 (mod (* 3 (- number-difference name-difference
))
197 (defun calendar-mayan-tzolkin-on-or-before (tzolkin-date date
)
198 "Absolute date of latest TZOLKIN-DATE on or before absolute DATE."
200 (%
(- date
(calendar-mayan-tzolkin-difference
201 (calendar-mayan-tzolkin-from-absolute 0)
205 (defun calendar-next-tzolkin-date (tzolkin-date &optional noecho
)
206 "Move cursor to next instance of Mayan TZOLKIN-DATE.
207 Echo Mayan date if NOECHO is t."
208 (interactive (list (calendar-read-mayan-tzolkin-date)))
210 (calendar-gregorian-from-absolute
211 (calendar-mayan-tzolkin-on-or-before
214 (calendar-absolute-from-gregorian (calendar-cursor-to-date))))))
215 (or noecho
(calendar-print-mayan-date)))
217 (defun calendar-previous-tzolkin-date (tzolkin-date &optional noecho
)
218 "Move cursor to previous instance of Mayan TZOLKIN-DATE.
219 Echo Mayan date if NOECHO is t."
220 (interactive (list (calendar-read-mayan-tzolkin-date)))
222 (calendar-gregorian-from-absolute
223 (calendar-mayan-tzolkin-on-or-before
225 (1- (calendar-absolute-from-gregorian (calendar-cursor-to-date))))))
226 (or noecho
(calendar-print-mayan-date)))
228 (defun calendar-mayan-tzolkin-to-string (tzolkin)
229 "Convert Mayan tzolkin date (a pair) into its traditional written form."
232 (aref calendar-mayan-tzolkin-names-array
(1- (cdr tzolkin
)))))
234 (defun calendar-mayan-tzolkin-haab-on-or-before (tzolkin-date haab-date date
)
235 "Absolute date that is Mayan TZOLKIN-DATE and HAAB-DATE.
236 Latest such date on or before DATE.
237 Returns nil if such a tzolkin-haab combination is impossible."
238 (let* ((haab-difference
239 (calendar-mayan-haab-difference
240 (calendar-mayan-haab-from-absolute 0)
243 (calendar-mayan-tzolkin-difference
244 (calendar-mayan-tzolkin-from-absolute 0)
246 (difference (- tzolkin-difference haab-difference
)))
247 (if (= (% difference
5) 0)
250 (+ haab-difference
(* 365 difference
)))
254 (defun calendar-read-mayan-haab-date ()
255 "Prompt for a Mayan haab date"
256 (let* ((completion-ignore-case t
)
257 (haab-day (calendar-read
259 '(lambda (x) (and (>= x
0) (< x
20)))))
260 (haab-month-list (append calendar-mayan-haab-month-name-array
261 (and (< haab-day
5) '("Uayeb"))))
264 (completing-read "Haab uinal: "
265 (mapcar 'list haab-month-list
)
267 (calendar-make-alist haab-month-list
1) t
))))
268 (cons haab-day haab-month
)))
270 (defun calendar-read-mayan-tzolkin-date ()
271 "Prompt for a Mayan tzolkin date"
272 (let* ((completion-ignore-case t
)
273 (tzolkin-count (calendar-read
274 "Tzolkin kin (1-13): "
275 '(lambda (x) (and (> x
0) (< x
14)))))
276 (tzolkin-name-list (append calendar-mayan-tzolkin-names-array nil
))
279 (completing-read "Tzolkin uinal: "
280 (mapcar 'list tzolkin-name-list
)
282 (calendar-make-alist tzolkin-name-list
1) t
))))
283 (cons tzolkin-count tzolkin-name
)))
285 (defun calendar-next-calendar-round-date
286 (tzolkin-date haab-date
&optional noecho
)
287 "Move cursor to next instance of Mayan HAAB-DATE TZOLKIN-DATE combination.
288 Echo Mayan date if NOECHO is t."
289 (interactive (list (calendar-read-mayan-tzolkin-date)
290 (calendar-read-mayan-haab-date)))
291 (let ((date (calendar-mayan-tzolkin-haab-on-or-before
292 tzolkin-date haab-date
293 (+ 18980 (calendar-absolute-from-gregorian
294 (calendar-cursor-to-date))))))
296 (error "%s, %s does not exist in the Mayan calendar round"
297 (calendar-mayan-tzolkin-to-string tzolkin-date
)
298 (calendar-mayan-haab-to-string haab-date
))
299 (calendar-goto-date (calendar-gregorian-from-absolute date
))
300 (or noecho
(calendar-print-mayan-date)))))
302 (defun calendar-previous-calendar-round-date
303 (tzolkin-date haab-date
&optional noecho
)
304 "Move to previous instance of Mayan TZOLKIN-DATE HAAB-DATE combination.
305 Echo Mayan date if NOECHO is t."
306 (interactive (list (calendar-read-mayan-tzolkin-date)
307 (calendar-read-mayan-haab-date)))
308 (let ((date (calendar-mayan-tzolkin-haab-on-or-before
309 tzolkin-date haab-date
310 (1- (calendar-absolute-from-gregorian
311 (calendar-cursor-to-date))))))
313 (error "%s, %s does not exist in the Mayan calendar round"
314 (calendar-mayan-tzolkin-to-string tzolkin-date
)
315 (calendar-mayan-haab-to-string haab-date
))
316 (calendar-goto-date (calendar-gregorian-from-absolute date
))
317 (or noecho
(calendar-print-mayan-date)))))
319 (defun calendar-absolute-from-mayan-long-count (c)
320 "Compute the absolute date corresponding to the Mayan Long Count C.
321 Long count is a list (baktun katun tun uinal kin)"
322 (+ (* (nth 0 c
) 144000) ; baktun
323 (* (nth 1 c
) 7200) ; katun
324 (* (nth 2 c
) 360) ; tun
325 (* (nth 3 c
) 20) ; uinal
326 (nth 4 c
) ; kin (days)
327 (- ; days before absolute date 0
328 calendar-mayan-days-before-absolute-zero
)))
330 (defun calendar-mayan-date-string (&optional date
)
331 "String of Mayan date of Gregorian DATE.
332 Defaults to today's date if DATE is not given."
333 (let* ((d (calendar-absolute-from-gregorian
334 (or date
(calendar-current-date))))
335 (tzolkin (calendar-mayan-tzolkin-from-absolute d
))
336 (haab (calendar-mayan-haab-from-absolute d
))
337 (long-count (calendar-mayan-long-count-from-absolute d
)))
338 (format "Long count = %s; tzolkin = %s; haab = %s"
339 (calendar-mayan-long-count-to-string long-count
)
340 (calendar-mayan-tzolkin-to-string tzolkin
)
341 (calendar-mayan-haab-to-string haab
))))
343 (defun calendar-print-mayan-date ()
344 "Show the Mayan long count, tzolkin, and haab equivalents of date."
346 (message "Mayan date: %s"
347 (calendar-mayan-date-string (calendar-cursor-to-date t
))))
349 (defun calendar-goto-mayan-long-count-date (date &optional noecho
)
350 "Move cursor to Mayan long count DATE. Echo Mayan date unless NOECHO is t."
355 (calendar-string-to-mayan-long-count
356 (read-string "Mayan long count (baktun.katun.tun.uinal.kin): "
357 (calendar-mayan-long-count-to-string
358 (calendar-mayan-long-count-from-absolute
359 (calendar-absolute-from-gregorian
360 (calendar-current-date))))))))
361 (if (calendar-mayan-long-count-common-era datum
)
365 (calendar-gregorian-from-absolute
366 (calendar-absolute-from-mayan-long-count date
)))
367 (or noecho
(calendar-print-mayan-date)))
369 (defun calendar-mayan-long-count-common-era (lc)
370 "T if long count represents date in the Common Era."
371 (let ((base (calendar-mayan-long-count-from-absolute 1)))
372 (while (and (not (null base
)) (= (car lc
) (car base
)))
375 (or (null lc
) (> (car lc
) (car base
)))))
377 (defun diary-mayan-date ()
378 "Show the Mayan long count, haab, and tzolkin dates as a diary entry."
379 (format "Mayan date: %s" (calendar-mayan-date-string date
)))
383 ;;; arch-tag: 54f35144-cd0f-4873-935a-a60129de07df
384 ;;; cal-mayan.el ends here