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3afbc435 | 1 | ;;; cal-mayan.el --- calendar functions for the Mayan calendars |
7e1dae73 | 2 | |
a96a5fca | 3 | ;; Copyright (C) 1992, 1993, 1995, 1997 Free Software Foundation, Inc. |
7e1dae73 JB |
4 | |
5 | ;; Author: Stewart M. Clamen <clamen@cs.cmu.edu> | |
6 | ;; Edward M. Reingold <reingold@cs.uiuc.edu> | |
e9571d2a ER |
7 | ;; Keywords: calendar |
8 | ;; Human-Keywords: Mayan calendar, Maya, calendar, diary | |
7e1dae73 JB |
9 | |
10 | ;; This file is part of GNU Emacs. | |
11 | ||
59243403 RS |
12 | ;; GNU Emacs is free software; you can redistribute it and/or modify |
13 | ;; it under the terms of the GNU General Public License as published by | |
14 | ;; the Free Software Foundation; either version 2, or (at your option) | |
15 | ;; any later version. | |
16 | ||
7e1dae73 | 17 | ;; GNU Emacs is distributed in the hope that it will be useful, |
59243403 RS |
18 | ;; but WITHOUT ANY WARRANTY; without even the implied warranty of |
19 | ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
20 | ;; GNU General Public License for more details. | |
21 | ||
22 | ;; You should have received a copy of the GNU General Public License | |
b578f267 EN |
23 | ;; along with GNU Emacs; see the file COPYING. If not, write to the |
24 | ;; Free Software Foundation, Inc., 59 Temple Place - Suite 330, | |
25 | ;; Boston, MA 02111-1307, USA. | |
7e1dae73 JB |
26 | |
27 | ;;; Commentary: | |
28 | ||
29 | ;; This collection of functions implements the features of calendar.el and | |
30 | ;; diary.el that deal with the Mayan calendar. It was written jointly by | |
31 | ||
32 | ;; Stewart M. Clamen School of Computer Science | |
33 | ;; clamen@cs.cmu.edu Carnegie Mellon University | |
34 | ;; 5000 Forbes Avenue | |
35 | ;; Pittsburgh, PA 15213 | |
36 | ||
37 | ;; and | |
38 | ||
39 | ;; Edward M. Reingold Department of Computer Science | |
40 | ;; (217) 333-6733 University of Illinois at Urbana-Champaign | |
41 | ;; reingold@cs.uiuc.edu 1304 West Springfield Avenue | |
42 | ;; Urbana, Illinois 61801 | |
43 | ||
44 | ;; Comments, improvements, and bug reports should be sent to Reingold. | |
45 | ||
46 | ;; Technical details of the Mayan calendrical calculations can be found in | |
a96a5fca PE |
47 | ;; ``Calendrical Calculations'' by Nachum Dershowitz and Edward M. Reingold, |
48 | ;; Cambridge University Press (1997), and in | |
7e1dae73 JB |
49 | ;; ``Calendrical Calculations, Part II: Three Historical Calendars'' |
50 | ;; by E. M. Reingold, N. Dershowitz, and S. M. Clamen, | |
c8d190a5 JB |
51 | ;; Software--Practice and Experience, Volume 23, Number 4 (April, 1993), |
52 | ;; pages 383-404. | |
7e1dae73 JB |
53 | |
54 | ;;; Code: | |
55 | ||
56 | (require 'calendar) | |
57 | ||
686481e7 | 58 | (defconst calendar-mayan-days-before-absolute-zero 1137142 |
c6b6c929 | 59 | "Number of days of the Mayan calendar epoch before absolute day 0. |
686481e7 KH |
60 | This is the Goodman-Martinez-Thompson correlation used by almost all experts, |
61 | but some use 1137140. Using 1232041 gives you Spinden's correlation; using | |
62 | 1142840 gives you Hochleitner's correlation.") | |
7e1dae73 JB |
63 | |
64 | (defconst calendar-mayan-haab-at-epoch '(8 . 18) | |
65 | "Mayan haab date at the epoch.") | |
66 | ||
67 | (defconst calendar-mayan-haab-month-name-array | |
68 | ["Pop" "Uo" "Zip" "Zotz" "Tzec" "Xul" "Yaxkin" "Mol" "Chen" "Yax" | |
69 | "Zac" "Ceh" "Mac" "Kankin" "Muan" "Pax" "Kayab" "Cumku"]) | |
70 | ||
71 | (defconst calendar-mayan-tzolkin-at-epoch '(4 . 20) | |
72 | "Mayan tzolkin date at the epoch.") | |
73 | ||
74 | (defconst calendar-mayan-tzolkin-names-array | |
75 | ["Imix" "Ik" "Akbal" "Kan" "Chicchan" "Cimi" "Manik" "Lamat" "Muluc" "Oc" | |
76 | "Chuen" "Eb" "Ben" "Ix" "Men" "Cib" "Caban" "Etznab" "Cauac" "Ahau"]) | |
77 | ||
78 | (defun calendar-mayan-long-count-from-absolute (date) | |
79 | "Compute the Mayan long count corresponding to the absolute DATE." | |
80 | (let ((long-count (+ date calendar-mayan-days-before-absolute-zero))) | |
81 | (let* ((baktun (/ long-count 144000)) | |
82 | (remainder (% long-count 144000)) | |
83 | (katun (/ remainder 7200)) | |
84 | (remainder (% remainder 7200)) | |
85 | (tun (/ remainder 360)) | |
86 | (remainder (% remainder 360)) | |
87 | (uinal (/ remainder 20)) | |
88 | (kin (% remainder 20))) | |
89 | (list baktun katun tun uinal kin)))) | |
90 | ||
91 | (defun calendar-mayan-long-count-to-string (mayan-long-count) | |
92 | "Convert MAYAN-LONG-COUNT into traditional written form." | |
93 | (apply 'format (cons "%s.%s.%s.%s.%s" mayan-long-count))) | |
94 | ||
95 | (defun calendar-string-to-mayan-long-count (str) | |
96 | "Given STR, a string of format \"%d.%d.%d.%d.%d\", return list of nums." | |
97 | (let ((rlc nil) | |
98 | (c (length str)) | |
99 | (cc 0)) | |
100 | (condition-case condition | |
101 | (progn | |
102 | (while (< cc c) | |
7cd96b42 RS |
103 | (let* ((start (string-match "[0-9]+" str cc)) |
104 | (end (match-end 0)) | |
105 | datum) | |
106 | (setq datum (read (substring str start end))) | |
107 | (setq rlc (cons datum rlc)) | |
108 | (setq cc end))) | |
7e1dae73 JB |
109 | (if (not (= (length rlc) 5)) (signal 'invalid-read-syntax nil))) |
110 | (invalid-read-syntax nil)) | |
111 | (reverse rlc))) | |
112 | ||
113 | (defun calendar-mayan-haab-from-absolute (date) | |
114 | "Convert absolute DATE into a Mayan haab date (a pair)." | |
115 | (let* ((long-count (+ date calendar-mayan-days-before-absolute-zero)) | |
116 | (day-of-haab | |
117 | (% (+ long-count | |
118 | (car calendar-mayan-haab-at-epoch) | |
119 | (* 20 (1- (cdr calendar-mayan-haab-at-epoch)))) | |
120 | 365)) | |
121 | (day (% day-of-haab 20)) | |
122 | (month (1+ (/ day-of-haab 20)))) | |
123 | (cons day month))) | |
124 | ||
125 | (defun calendar-mayan-haab-difference (date1 date2) | |
c6b6c929 | 126 | "Number of days from Mayan haab DATE1 to next occurrence of haab date DATE2." |
632f9a0e PE |
127 | (mod (+ (* 20 (- (cdr date2) (cdr date1))) |
128 | (- (car date2) (car date1))) | |
129 | 365)) | |
7e1dae73 JB |
130 | |
131 | (defun calendar-mayan-haab-on-or-before (haab-date date) | |
132 | "Absolute date of latest HAAB-DATE on or before absolute DATE." | |
63f76385 JB |
133 | (- date |
134 | (% (- date | |
135 | (calendar-mayan-haab-difference | |
136 | (calendar-mayan-haab-from-absolute 0) haab-date)) | |
137 | 365))) | |
7e1dae73 JB |
138 | |
139 | (defun calendar-next-haab-date (haab-date &optional noecho) | |
a1506d29 | 140 | "Move cursor to next instance of Mayan HAAB-DATE. |
7e1dae73 JB |
141 | Echo Mayan date if NOECHO is t." |
142 | (interactive (list (calendar-read-mayan-haab-date))) | |
143 | (calendar-goto-date | |
144 | (calendar-gregorian-from-absolute | |
145 | (calendar-mayan-haab-on-or-before | |
146 | haab-date | |
147 | (+ 365 | |
148 | (calendar-absolute-from-gregorian (calendar-cursor-to-date)))))) | |
149 | (or noecho (calendar-print-mayan-date))) | |
150 | ||
151 | (defun calendar-previous-haab-date (haab-date &optional noecho) | |
a1506d29 | 152 | "Move cursor to previous instance of Mayan HAAB-DATE. |
7e1dae73 JB |
153 | Echo Mayan date if NOECHO is t." |
154 | (interactive (list (calendar-read-mayan-haab-date))) | |
155 | (calendar-goto-date | |
156 | (calendar-gregorian-from-absolute | |
157 | (calendar-mayan-haab-on-or-before | |
158 | haab-date | |
159 | (1- (calendar-absolute-from-gregorian (calendar-cursor-to-date)))))) | |
160 | (or noecho (calendar-print-mayan-date))) | |
161 | ||
162 | (defun calendar-mayan-haab-to-string (haab) | |
163 | "Convert Mayan haab date (a pair) into its traditional written form." | |
164 | (let ((month (cdr haab)) | |
165 | (day (car haab))) | |
166 | ;; 19th month consists of 5 special days | |
167 | (if (= month 19) | |
168 | (format "%d Uayeb" day) | |
169 | (format "%d %s" | |
170 | day | |
171 | (aref calendar-mayan-haab-month-name-array (1- month)))))) | |
172 | ||
173 | (defun calendar-mayan-tzolkin-from-absolute (date) | |
174 | "Convert absolute DATE into a Mayan tzolkin date (a pair)." | |
175 | (let* ((long-count (+ date calendar-mayan-days-before-absolute-zero)) | |
9fadf1a5 | 176 | (day (calendar-mod |
7e1dae73 JB |
177 | (+ long-count (car calendar-mayan-tzolkin-at-epoch)) |
178 | 13)) | |
9fadf1a5 | 179 | (name (calendar-mod |
7e1dae73 JB |
180 | (+ long-count (cdr calendar-mayan-tzolkin-at-epoch)) |
181 | 20))) | |
182 | (cons day name))) | |
183 | ||
184 | (defun calendar-mayan-tzolkin-difference (date1 date2) | |
c6b6c929 | 185 | "Number of days from Mayan tzolkin DATE1 to next occurrence of tzolkin DATE2." |
7e1dae73 JB |
186 | (let ((number-difference (- (car date2) (car date1))) |
187 | (name-difference (- (cdr date2) (cdr date1)))) | |
632f9a0e PE |
188 | (mod (+ number-difference |
189 | (* 13 (mod (* 3 (- number-difference name-difference)) | |
190 | 20))) | |
191 | 260))) | |
7e1dae73 JB |
192 | |
193 | (defun calendar-mayan-tzolkin-on-or-before (tzolkin-date date) | |
194 | "Absolute date of latest TZOLKIN-DATE on or before absolute DATE." | |
63f76385 JB |
195 | (- date |
196 | (% (- date (calendar-mayan-tzolkin-difference | |
197 | (calendar-mayan-tzolkin-from-absolute 0) | |
198 | tzolkin-date)) | |
199 | 260))) | |
7e1dae73 JB |
200 | |
201 | (defun calendar-next-tzolkin-date (tzolkin-date &optional noecho) | |
a1506d29 | 202 | "Move cursor to next instance of Mayan TZOLKIN-DATE. |
7e1dae73 JB |
203 | Echo Mayan date if NOECHO is t." |
204 | (interactive (list (calendar-read-mayan-tzolkin-date))) | |
205 | (calendar-goto-date | |
206 | (calendar-gregorian-from-absolute | |
207 | (calendar-mayan-tzolkin-on-or-before | |
208 | tzolkin-date | |
209 | (+ 260 | |
210 | (calendar-absolute-from-gregorian (calendar-cursor-to-date)))))) | |
211 | (or noecho (calendar-print-mayan-date))) | |
212 | ||
213 | (defun calendar-previous-tzolkin-date (tzolkin-date &optional noecho) | |
a1506d29 | 214 | "Move cursor to previous instance of Mayan TZOLKIN-DATE. |
7e1dae73 JB |
215 | Echo Mayan date if NOECHO is t." |
216 | (interactive (list (calendar-read-mayan-tzolkin-date))) | |
217 | (calendar-goto-date | |
218 | (calendar-gregorian-from-absolute | |
219 | (calendar-mayan-tzolkin-on-or-before | |
220 | tzolkin-date | |
221 | (1- (calendar-absolute-from-gregorian (calendar-cursor-to-date)))))) | |
222 | (or noecho (calendar-print-mayan-date))) | |
223 | ||
224 | (defun calendar-mayan-tzolkin-to-string (tzolkin) | |
225 | "Convert Mayan tzolkin date (a pair) into its traditional written form." | |
226 | (format "%d %s" | |
227 | (car tzolkin) | |
228 | (aref calendar-mayan-tzolkin-names-array (1- (cdr tzolkin))))) | |
229 | ||
230 | (defun calendar-mayan-tzolkin-haab-on-or-before (tzolkin-date haab-date date) | |
c6b6c929 JB |
231 | "Absolute date that is Mayan TZOLKIN-DATE and HAAB-DATE. |
232 | Latest such date on or before DATE. | |
a1506d29 | 233 | Returns nil if such a tzolkin-haab combination is impossible." |
7e1dae73 JB |
234 | (let* ((haab-difference |
235 | (calendar-mayan-haab-difference | |
236 | (calendar-mayan-haab-from-absolute 0) | |
237 | haab-date)) | |
238 | (tzolkin-difference | |
239 | (calendar-mayan-tzolkin-difference | |
240 | (calendar-mayan-tzolkin-from-absolute 0) | |
241 | tzolkin-date)) | |
242 | (difference (- tzolkin-difference haab-difference))) | |
243 | (if (= (% difference 5) 0) | |
244 | (- date | |
632f9a0e PE |
245 | (mod (- date |
246 | (+ haab-difference (* 365 difference))) | |
247 | 18980)) | |
7e1dae73 JB |
248 | nil))) |
249 | ||
250 | (defun calendar-read-mayan-haab-date () | |
251 | "Prompt for a Mayan haab date" | |
252 | (let* ((completion-ignore-case t) | |
253 | (haab-day (calendar-read | |
254 | "Haab kin (0-19): " | |
255 | '(lambda (x) (and (>= x 0) (< x 20))))) | |
a1506d29 | 256 | (haab-month-list (append calendar-mayan-haab-month-name-array |
7e1dae73 JB |
257 | (and (< haab-day 5) '("Uayeb")))) |
258 | (haab-month (cdr | |
6b61353c | 259 | (assoc-string |
918358c9 RS |
260 | (completing-read "Haab uinal: " |
261 | (mapcar 'list haab-month-list) | |
262 | nil t) | |
6b61353c | 263 | (calendar-make-alist haab-month-list 1) t)))) |
7e1dae73 JB |
264 | (cons haab-day haab-month))) |
265 | ||
266 | (defun calendar-read-mayan-tzolkin-date () | |
267 | "Prompt for a Mayan tzolkin date" | |
268 | (let* ((completion-ignore-case t) | |
269 | (tzolkin-count (calendar-read | |
270 | "Tzolkin kin (1-13): " | |
271 | '(lambda (x) (and (> x 0) (< x 14))))) | |
272 | (tzolkin-name-list (append calendar-mayan-tzolkin-names-array nil)) | |
273 | (tzolkin-name (cdr | |
6b61353c | 274 | (assoc-string |
a1506d29 | 275 | (completing-read "Tzolkin uinal: " |
7e1dae73 | 276 | (mapcar 'list tzolkin-name-list) |
918358c9 | 277 | nil t) |
6b61353c | 278 | (calendar-make-alist tzolkin-name-list 1) t)))) |
7e1dae73 JB |
279 | (cons tzolkin-count tzolkin-name))) |
280 | ||
7e1dae73 JB |
281 | (defun calendar-next-calendar-round-date |
282 | (tzolkin-date haab-date &optional noecho) | |
aeaa056e | 283 | "Move cursor to next instance of Mayan HAAB-DATE TZOLKIN-DATE combination. |
7e1dae73 JB |
284 | Echo Mayan date if NOECHO is t." |
285 | (interactive (list (calendar-read-mayan-tzolkin-date) | |
286 | (calendar-read-mayan-haab-date))) | |
287 | (let ((date (calendar-mayan-tzolkin-haab-on-or-before | |
288 | tzolkin-date haab-date | |
289 | (+ 18980 (calendar-absolute-from-gregorian | |
290 | (calendar-cursor-to-date)))))) | |
291 | (if (not date) | |
292 | (error "%s, %s does not exist in the Mayan calendar round" | |
293 | (calendar-mayan-tzolkin-to-string tzolkin-date) | |
294 | (calendar-mayan-haab-to-string haab-date)) | |
295 | (calendar-goto-date (calendar-gregorian-from-absolute date)) | |
296 | (or noecho (calendar-print-mayan-date))))) | |
297 | ||
298 | (defun calendar-previous-calendar-round-date | |
299 | (tzolkin-date haab-date &optional noecho) | |
aeaa056e | 300 | "Move to previous instance of Mayan TZOLKIN-DATE HAAB-DATE combination. |
c6b6c929 | 301 | Echo Mayan date if NOECHO is t." |
7e1dae73 JB |
302 | (interactive (list (calendar-read-mayan-tzolkin-date) |
303 | (calendar-read-mayan-haab-date))) | |
304 | (let ((date (calendar-mayan-tzolkin-haab-on-or-before | |
305 | tzolkin-date haab-date | |
306 | (1- (calendar-absolute-from-gregorian | |
307 | (calendar-cursor-to-date)))))) | |
308 | (if (not date) | |
309 | (error "%s, %s does not exist in the Mayan calendar round" | |
310 | (calendar-mayan-tzolkin-to-string tzolkin-date) | |
311 | (calendar-mayan-haab-to-string haab-date)) | |
312 | (calendar-goto-date (calendar-gregorian-from-absolute date)) | |
313 | (or noecho (calendar-print-mayan-date))))) | |
314 | ||
315 | (defun calendar-absolute-from-mayan-long-count (c) | |
c6b6c929 JB |
316 | "Compute the absolute date corresponding to the Mayan Long Count C. |
317 | Long count is a list (baktun katun tun uinal kin)" | |
7e1dae73 JB |
318 | (+ (* (nth 0 c) 144000) ; baktun |
319 | (* (nth 1 c) 7200) ; katun | |
320 | (* (nth 2 c) 360) ; tun | |
321 | (* (nth 3 c) 20) ; uinal | |
322 | (nth 4 c) ; kin (days) | |
323 | (- ; days before absolute date 0 | |
324 | calendar-mayan-days-before-absolute-zero))) | |
325 | ||
45cb347b RS |
326 | (defun calendar-mayan-date-string (&optional date) |
327 | "String of Mayan date of Gregorian DATE. | |
328 | Defaults to today's date if DATE is not given." | |
a1506d29 | 329 | (let* ((d (calendar-absolute-from-gregorian |
45cb347b RS |
330 | (or date (calendar-current-date)))) |
331 | (tzolkin (calendar-mayan-tzolkin-from-absolute d)) | |
332 | (haab (calendar-mayan-haab-from-absolute d)) | |
333 | (long-count (calendar-mayan-long-count-from-absolute d))) | |
334 | (format "Long count = %s; tzolkin = %s; haab = %s" | |
335 | (calendar-mayan-long-count-to-string long-count) | |
336 | (calendar-mayan-tzolkin-to-string tzolkin) | |
337 | (calendar-mayan-haab-to-string haab)))) | |
338 | ||
7e1dae73 | 339 | (defun calendar-print-mayan-date () |
c6b6c929 | 340 | "Show the Mayan long count, tzolkin, and haab equivalents of date." |
7e1dae73 | 341 | (interactive) |
45cb347b | 342 | (message "Mayan date: %s" |
d33b3958 | 343 | (calendar-mayan-date-string (calendar-cursor-to-date t)))) |
7e1dae73 JB |
344 | |
345 | (defun calendar-goto-mayan-long-count-date (date &optional noecho) | |
346 | "Move cursor to Mayan long count DATE. Echo Mayan date unless NOECHO is t." | |
347 | (interactive | |
348 | (let (lc) | |
349 | (while (not lc) | |
350 | (let ((datum | |
a1506d29 | 351 | (calendar-string-to-mayan-long-count |
7e1dae73 JB |
352 | (read-string "Mayan long count (baktun.katun.tun.uinal.kin): " |
353 | (calendar-mayan-long-count-to-string | |
354 | (calendar-mayan-long-count-from-absolute | |
355 | (calendar-absolute-from-gregorian | |
356 | (calendar-current-date)))))))) | |
357 | (if (calendar-mayan-long-count-common-era datum) | |
358 | (setq lc datum)))) | |
359 | (list lc))) | |
360 | (calendar-goto-date | |
361 | (calendar-gregorian-from-absolute | |
362 | (calendar-absolute-from-mayan-long-count date))) | |
363 | (or noecho (calendar-print-mayan-date))) | |
a1506d29 | 364 | |
7e1dae73 JB |
365 | (defun calendar-mayan-long-count-common-era (lc) |
366 | "T if long count represents date in the Common Era." | |
367 | (let ((base (calendar-mayan-long-count-from-absolute 1))) | |
368 | (while (and (not (null base)) (= (car lc) (car base))) | |
369 | (setq lc (cdr lc) | |
370 | base (cdr base))) | |
371 | (or (null lc) (> (car lc) (car base))))) | |
372 | ||
373 | (defun diary-mayan-date () | |
374 | "Show the Mayan long count, haab, and tzolkin dates as a diary entry." | |
45cb347b | 375 | (format "Mayan date: %s" (calendar-mayan-date-string date))) |
7e1dae73 JB |
376 | |
377 | (provide 'cal-mayan) | |
378 | ||
6b61353c | 379 | ;;; arch-tag: 54f35144-cd0f-4873-935a-a60129de07df |
7e1dae73 | 380 | ;;; cal-mayan.el ends here |