cal-mayan.el 15.3 KB
Newer Older
1
;;; cal-mayan.el --- calendar functions for the Mayan calendars
Jim Blandy's avatar
Jim Blandy committed
2

3 4
;; Copyright (C) 1992, 1993, 1995, 1997, 2001, 2002, 2003, 2004, 2005
;;   Free Software Foundation, Inc.
Jim Blandy's avatar
Jim Blandy committed
5 6 7

;; Author: Stewart M. Clamen <clamen@cs.cmu.edu>
;;	Edward M. Reingold <reingold@cs.uiuc.edu>
8
;; Maintainer: Glenn Morris <rgm@gnu.org>
Eric S. Raymond's avatar
Eric S. Raymond committed
9 10
;; Keywords: calendar
;; Human-Keywords: Mayan calendar, Maya, calendar, diary
Jim Blandy's avatar
Jim Blandy committed
11 12 13

;; This file is part of GNU Emacs.

14 15 16 17 18
;; 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.

Jim Blandy's avatar
Jim Blandy committed
19
;; GNU Emacs is distributed in the hope that it will be useful,
20 21 22 23 24
;; 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
Erik Naggum's avatar
Erik Naggum committed
25
;; along with GNU Emacs; see the file COPYING.  If not, write to the
Lute Kamstra's avatar
Lute Kamstra committed
26 27
;; Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
;; Boston, MA 02110-1301, USA.
Jim Blandy's avatar
Jim Blandy committed
28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48

;;; Commentary:

;; This collection of functions implements the features of calendar.el and
;; diary.el that deal with the Mayan calendar.  It was written jointly by

;;  Stewart M. Clamen                School of Computer Science
;;  clamen@cs.cmu.edu                Carnegie Mellon University
;;                                   5000 Forbes Avenue
;;                                   Pittsburgh, PA 15213

;; and

;;  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

;; Comments, improvements, and bug reports should be sent to Reingold.

;; Technical details of the Mayan calendrical calculations can be found in
49 50
;; ``Calendrical Calculations: The Millennium Edition'' by Edward M. Reingold
;; and Nachum Dershowitz, Cambridge University Press (2001), and in
Jim Blandy's avatar
Jim Blandy committed
51 52
;; ``Calendrical Calculations, Part II: Three Historical Calendars''
;; by E. M. Reingold,  N. Dershowitz, and S. M. Clamen,
53 54
;; Software--Practice and Experience, Volume 23, Number 4 (April, 1993),
;; pages 383-404.
Jim Blandy's avatar
Jim Blandy committed
55 56 57

;;; Code:

Juanma Barranquero's avatar
Juanma Barranquero committed
58 59
(defvar date)

Jim Blandy's avatar
Jim Blandy committed
60 61
(require 'calendar)

62
(defconst calendar-mayan-days-before-absolute-zero 1137142
63
  "Number of days of the Mayan calendar epoch before absolute day 0.
64 65 66
This is the Goodman-Martinez-Thompson correlation used by almost all experts,
but some use 1137140.  Using 1232041 gives you Spinden's correlation; using
1142840 gives you Hochleitner's correlation.")
Jim Blandy's avatar
Jim Blandy committed
67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106

(defconst calendar-mayan-haab-at-epoch '(8 . 18)
  "Mayan haab date at the epoch.")

(defconst calendar-mayan-haab-month-name-array
  ["Pop" "Uo" "Zip" "Zotz" "Tzec" "Xul" "Yaxkin" "Mol" "Chen" "Yax"
   "Zac" "Ceh" "Mac" "Kankin" "Muan" "Pax" "Kayab" "Cumku"])

(defconst calendar-mayan-tzolkin-at-epoch '(4 . 20)
  "Mayan tzolkin date at the epoch.")

(defconst calendar-mayan-tzolkin-names-array
  ["Imix" "Ik" "Akbal" "Kan" "Chicchan" "Cimi" "Manik" "Lamat" "Muluc" "Oc"
   "Chuen" "Eb" "Ben" "Ix" "Men" "Cib" "Caban" "Etznab" "Cauac" "Ahau"])

(defun calendar-mayan-long-count-from-absolute (date)
  "Compute the Mayan long count corresponding to the absolute DATE."
  (let ((long-count (+ date calendar-mayan-days-before-absolute-zero)))
    (let* ((baktun (/ long-count 144000))
           (remainder (% long-count 144000))
           (katun (/ remainder 7200))
           (remainder (% remainder 7200))
           (tun (/ remainder 360))
           (remainder (% remainder 360))
           (uinal (/ remainder 20))
           (kin (% remainder 20)))
      (list baktun katun tun uinal kin))))

(defun calendar-mayan-long-count-to-string (mayan-long-count)
  "Convert MAYAN-LONG-COUNT into traditional written form."
  (apply 'format (cons "%s.%s.%s.%s.%s" mayan-long-count)))

(defun calendar-string-to-mayan-long-count (str)
  "Given STR, a string of format \"%d.%d.%d.%d.%d\", return list of nums."
  (let ((rlc nil)
        (c (length str))
        (cc 0))
    (condition-case condition
        (progn
          (while (< cc c)
107 108 109 110 111 112
	    (let* ((start (string-match "[0-9]+" str cc))
		   (end (match-end 0))
		   datum)
	      (setq datum (read (substring str start end)))
	      (setq rlc (cons datum rlc))
	      (setq cc end)))
Jim Blandy's avatar
Jim Blandy committed
113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129
          (if (not (= (length rlc) 5)) (signal 'invalid-read-syntax nil)))
      (invalid-read-syntax nil))
    (reverse rlc)))

(defun calendar-mayan-haab-from-absolute (date)
  "Convert absolute DATE into a Mayan haab date (a pair)."
  (let* ((long-count (+ date calendar-mayan-days-before-absolute-zero))
         (day-of-haab
          (% (+ long-count
                (car calendar-mayan-haab-at-epoch)
                (* 20 (1- (cdr calendar-mayan-haab-at-epoch))))
             365))
         (day (% day-of-haab 20))
         (month (1+ (/ day-of-haab 20))))
    (cons day month)))

(defun calendar-mayan-haab-difference (date1 date2)
130
  "Number of days from Mayan haab DATE1 to next occurrence of haab date DATE2."
131 132 133
  (mod (+ (* 20 (- (cdr date2) (cdr date1)))
	  (- (car date2) (car date1)))
       365))
Jim Blandy's avatar
Jim Blandy committed
134 135 136

(defun calendar-mayan-haab-on-or-before (haab-date date)
  "Absolute date of latest HAAB-DATE on or before absolute DATE."
137 138 139 140 141
  (- date
     (% (- date
	   (calendar-mayan-haab-difference
	    (calendar-mayan-haab-from-absolute 0) haab-date))
	365)))
Jim Blandy's avatar
Jim Blandy committed
142 143

(defun calendar-next-haab-date (haab-date &optional noecho)
144
  "Move cursor to next instance of Mayan HAAB-DATE.
Jim Blandy's avatar
Jim Blandy committed
145 146 147 148 149 150 151 152 153 154 155
Echo Mayan date if NOECHO is t."
  (interactive (list (calendar-read-mayan-haab-date)))
  (calendar-goto-date
   (calendar-gregorian-from-absolute
    (calendar-mayan-haab-on-or-before
     haab-date
     (+ 365
        (calendar-absolute-from-gregorian (calendar-cursor-to-date))))))
  (or noecho (calendar-print-mayan-date)))

(defun calendar-previous-haab-date (haab-date &optional noecho)
156
  "Move cursor to previous instance of Mayan HAAB-DATE.
Jim Blandy's avatar
Jim Blandy committed
157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179
Echo Mayan date if NOECHO is t."
  (interactive (list (calendar-read-mayan-haab-date)))
  (calendar-goto-date
   (calendar-gregorian-from-absolute
    (calendar-mayan-haab-on-or-before
     haab-date
     (1- (calendar-absolute-from-gregorian (calendar-cursor-to-date))))))
  (or noecho (calendar-print-mayan-date)))

(defun calendar-mayan-haab-to-string (haab)
  "Convert Mayan haab date (a pair) into its traditional written form."
  (let ((month (cdr haab))
        (day (car haab)))
  ;; 19th month consists of 5 special days
  (if (= month 19)
      (format "%d Uayeb" day)
    (format "%d %s"
            day
            (aref calendar-mayan-haab-month-name-array (1- month))))))

(defun calendar-mayan-tzolkin-from-absolute (date)
  "Convert absolute DATE into a Mayan tzolkin date (a pair)."
  (let* ((long-count (+ date calendar-mayan-days-before-absolute-zero))
Edward M. Reingold's avatar
Edward M. Reingold committed
180
         (day (calendar-mod
Jim Blandy's avatar
Jim Blandy committed
181 182
               (+ long-count (car calendar-mayan-tzolkin-at-epoch))
               13))
Edward M. Reingold's avatar
Edward M. Reingold committed
183
         (name (calendar-mod
Jim Blandy's avatar
Jim Blandy committed
184 185 186 187 188
                (+ long-count (cdr calendar-mayan-tzolkin-at-epoch))
                20)))
    (cons day name)))

(defun calendar-mayan-tzolkin-difference (date1 date2)
189
  "Number of days from Mayan tzolkin DATE1 to next occurrence of tzolkin DATE2."
Jim Blandy's avatar
Jim Blandy committed
190 191
  (let ((number-difference (- (car date2) (car date1)))
        (name-difference (- (cdr date2) (cdr date1))))
192 193 194 195
    (mod (+ number-difference
	    (* 13 (mod (* 3 (- number-difference name-difference))
		       20)))
	 260)))
Jim Blandy's avatar
Jim Blandy committed
196 197 198

(defun calendar-mayan-tzolkin-on-or-before (tzolkin-date date)
  "Absolute date of latest TZOLKIN-DATE on or before absolute DATE."
199 200 201 202 203
  (- date
     (% (- date (calendar-mayan-tzolkin-difference
		 (calendar-mayan-tzolkin-from-absolute 0)
		 tzolkin-date))
	260)))
Jim Blandy's avatar
Jim Blandy committed
204 205

(defun calendar-next-tzolkin-date (tzolkin-date &optional noecho)
206
  "Move cursor to next instance of Mayan TZOLKIN-DATE.
Jim Blandy's avatar
Jim Blandy committed
207 208 209 210 211 212 213 214 215 216 217
Echo Mayan date if NOECHO is t."
  (interactive (list (calendar-read-mayan-tzolkin-date)))
  (calendar-goto-date
   (calendar-gregorian-from-absolute
    (calendar-mayan-tzolkin-on-or-before
     tzolkin-date
     (+ 260
        (calendar-absolute-from-gregorian (calendar-cursor-to-date))))))
  (or noecho (calendar-print-mayan-date)))

(defun calendar-previous-tzolkin-date (tzolkin-date &optional noecho)
218
  "Move cursor to previous instance of Mayan TZOLKIN-DATE.
Jim Blandy's avatar
Jim Blandy committed
219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234
Echo Mayan date if NOECHO is t."
  (interactive (list (calendar-read-mayan-tzolkin-date)))
  (calendar-goto-date
   (calendar-gregorian-from-absolute
    (calendar-mayan-tzolkin-on-or-before
     tzolkin-date
     (1- (calendar-absolute-from-gregorian (calendar-cursor-to-date))))))
  (or noecho (calendar-print-mayan-date)))

(defun calendar-mayan-tzolkin-to-string (tzolkin)
  "Convert Mayan tzolkin date (a pair) into its traditional written form."
  (format "%d %s"
          (car tzolkin)
          (aref calendar-mayan-tzolkin-names-array (1- (cdr tzolkin)))))

(defun calendar-mayan-tzolkin-haab-on-or-before (tzolkin-date haab-date date)
235 236
  "Absolute date that is Mayan TZOLKIN-DATE and HAAB-DATE.
Latest such date on or before DATE.
237
Returns nil if such a tzolkin-haab combination is impossible."
Jim Blandy's avatar
Jim Blandy committed
238 239 240 241 242 243 244 245 246 247 248
  (let* ((haab-difference
          (calendar-mayan-haab-difference
           (calendar-mayan-haab-from-absolute 0)
           haab-date))
         (tzolkin-difference
          (calendar-mayan-tzolkin-difference
           (calendar-mayan-tzolkin-from-absolute 0)
           tzolkin-date))
         (difference (- tzolkin-difference haab-difference)))
    (if (= (% difference 5) 0)
        (- date
249 250 251
           (mod (- date
		   (+ haab-difference (* 365 difference)))
		18980))
Jim Blandy's avatar
Jim Blandy committed
252 253 254 255 256 257 258 259
      nil)))

(defun calendar-read-mayan-haab-date ()
  "Prompt for a Mayan haab date"
  (let* ((completion-ignore-case t)
         (haab-day (calendar-read
                    "Haab kin (0-19): "
                    '(lambda (x) (and (>= x 0) (< x 20)))))
260
         (haab-month-list (append calendar-mayan-haab-month-name-array
Jim Blandy's avatar
Jim Blandy committed
261 262
                                  (and (< haab-day 5) '("Uayeb"))))
         (haab-month (cdr
263
                      (assoc-string
264 265 266
                       (completing-read "Haab uinal: "
                                        (mapcar 'list haab-month-list)
                                        nil t)
267
                       (calendar-make-alist haab-month-list 1) t))))
Jim Blandy's avatar
Jim Blandy committed
268 269 270 271 272 273 274 275 276 277
    (cons haab-day haab-month)))

(defun calendar-read-mayan-tzolkin-date ()
  "Prompt for a Mayan tzolkin date"
  (let* ((completion-ignore-case t)
         (tzolkin-count (calendar-read
                         "Tzolkin kin (1-13): "
                         '(lambda (x) (and (> x 0) (< x 14)))))
         (tzolkin-name-list (append calendar-mayan-tzolkin-names-array nil))
         (tzolkin-name (cdr
278
                        (assoc-string
279
                          (completing-read "Tzolkin uinal: "
Jim Blandy's avatar
Jim Blandy committed
280
                                           (mapcar 'list tzolkin-name-list)
281
                                           nil t)
282
                         (calendar-make-alist tzolkin-name-list 1) t))))
Jim Blandy's avatar
Jim Blandy committed
283 284 285 286
    (cons tzolkin-count tzolkin-name)))

(defun calendar-next-calendar-round-date
  (tzolkin-date haab-date &optional noecho)
287
  "Move cursor to next instance of Mayan HAAB-DATE TZOLKIN-DATE combination.
Jim Blandy's avatar
Jim Blandy committed
288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303
Echo Mayan date if NOECHO is t."
  (interactive (list (calendar-read-mayan-tzolkin-date)
                     (calendar-read-mayan-haab-date)))
  (let ((date (calendar-mayan-tzolkin-haab-on-or-before
               tzolkin-date haab-date
               (+ 18980 (calendar-absolute-from-gregorian
                         (calendar-cursor-to-date))))))
    (if (not date)
        (error "%s, %s does not exist in the Mayan calendar round"
               (calendar-mayan-tzolkin-to-string tzolkin-date)
               (calendar-mayan-haab-to-string haab-date))
      (calendar-goto-date (calendar-gregorian-from-absolute date))
      (or noecho (calendar-print-mayan-date)))))

(defun calendar-previous-calendar-round-date
  (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."
Jim Blandy's avatar
Jim Blandy committed
306 307 308 309 310 311 312 313 314 315 316 317 318 319
  (interactive (list (calendar-read-mayan-tzolkin-date)
                     (calendar-read-mayan-haab-date)))
  (let ((date (calendar-mayan-tzolkin-haab-on-or-before
               tzolkin-date haab-date
               (1- (calendar-absolute-from-gregorian
                    (calendar-cursor-to-date))))))
    (if (not date)
        (error "%s, %s does not exist in the Mayan calendar round"
               (calendar-mayan-tzolkin-to-string tzolkin-date)
               (calendar-mayan-haab-to-string haab-date))
      (calendar-goto-date (calendar-gregorian-from-absolute date))
      (or noecho (calendar-print-mayan-date)))))

(defun calendar-absolute-from-mayan-long-count (c)
320 321
  "Compute the absolute date corresponding to the Mayan Long Count C.
Long count is a list (baktun katun tun uinal kin)"
Jim Blandy's avatar
Jim Blandy committed
322 323 324 325 326 327 328 329
  (+ (* (nth 0 c) 144000)        ; baktun
     (* (nth 1 c) 7200)          ; katun
     (* (nth 2 c) 360)           ; tun
     (* (nth 3 c) 20)            ; uinal
     (nth 4 c)                   ; kin (days)
     (-                          ; days before absolute date 0
      calendar-mayan-days-before-absolute-zero)))

330 331 332
(defun calendar-mayan-date-string (&optional date)
  "String of Mayan date of Gregorian DATE.
Defaults to today's date if DATE is not given."
333
  (let* ((d (calendar-absolute-from-gregorian
334 335 336 337 338 339 340 341 342
             (or date (calendar-current-date))))
         (tzolkin (calendar-mayan-tzolkin-from-absolute d))
         (haab (calendar-mayan-haab-from-absolute d))
         (long-count (calendar-mayan-long-count-from-absolute d)))
      (format "Long count = %s; tzolkin = %s; haab = %s"
              (calendar-mayan-long-count-to-string long-count)
              (calendar-mayan-tzolkin-to-string tzolkin)
              (calendar-mayan-haab-to-string haab))))

Jim Blandy's avatar
Jim Blandy committed
343
(defun calendar-print-mayan-date ()
344
  "Show the Mayan long count, tzolkin, and haab equivalents of date."
Jim Blandy's avatar
Jim Blandy committed
345
  (interactive)
346
  (message "Mayan date: %s"
347
           (calendar-mayan-date-string (calendar-cursor-to-date t))))
Jim Blandy's avatar
Jim Blandy committed
348 349 350 351 352 353 354

(defun calendar-goto-mayan-long-count-date (date &optional noecho)
  "Move cursor to Mayan long count DATE.  Echo Mayan date unless NOECHO is t."
  (interactive
   (let (lc)
     (while (not lc)
       (let ((datum
355
              (calendar-string-to-mayan-long-count
Jim Blandy's avatar
Jim Blandy committed
356 357 358 359 360 361 362 363 364 365 366 367
               (read-string "Mayan long count (baktun.katun.tun.uinal.kin): "
                            (calendar-mayan-long-count-to-string
                             (calendar-mayan-long-count-from-absolute
                               (calendar-absolute-from-gregorian
                                (calendar-current-date))))))))
         (if (calendar-mayan-long-count-common-era datum)
             (setq lc datum))))
     (list lc)))
  (calendar-goto-date
   (calendar-gregorian-from-absolute
    (calendar-absolute-from-mayan-long-count date)))
  (or noecho (calendar-print-mayan-date)))
368

Jim Blandy's avatar
Jim Blandy committed
369 370 371 372 373 374 375 376 377 378
(defun calendar-mayan-long-count-common-era (lc)
  "T if long count represents date in the Common Era."
  (let ((base (calendar-mayan-long-count-from-absolute 1)))
    (while (and (not (null base)) (= (car lc) (car base)))
      (setq lc (cdr lc)
            base (cdr base)))
    (or (null lc) (> (car lc) (car base)))))

(defun diary-mayan-date ()
  "Show the Mayan long count, haab, and tzolkin dates as a diary entry."
379
  (format "Mayan date: %s" (calendar-mayan-date-string date)))
Jim Blandy's avatar
Jim Blandy committed
380 381 382

(provide 'cal-mayan)

Miles Bader's avatar
Miles Bader committed
383
;;; arch-tag: 54f35144-cd0f-4873-935a-a60129de07df
Jim Blandy's avatar
Jim Blandy committed
384
;;; cal-mayan.el ends here