Commit | Line | Data |
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3afbc435 | 1 | ;;; lunar.el --- calendar functions for phases of the moon |
7e1dae73 | 2 | |
a96a5fca | 3 | ;; Copyright (C) 1992, 1993, 1995, 1997 Free Software Foundation, Inc. |
7e1dae73 JB |
4 | |
5 | ;; Author: Edward M. Reingold <reingold@cs.uiuc.edu> | |
e9571d2a ER |
6 | ;; Keywords: calendar |
7 | ;; Human-Keywords: moon, lunar phases, calendar, diary | |
7e1dae73 JB |
8 | |
9 | ;; This file is part of GNU Emacs. | |
10 | ||
59243403 RS |
11 | ;; GNU Emacs is free software; you can redistribute it and/or modify |
12 | ;; it under the terms of the GNU General Public License as published by | |
13 | ;; the Free Software Foundation; either version 2, or (at your option) | |
14 | ;; any later version. | |
15 | ||
7e1dae73 | 16 | ;; GNU Emacs is distributed in the hope that it will be useful, |
59243403 RS |
17 | ;; but WITHOUT ANY WARRANTY; without even the implied warranty of |
18 | ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
19 | ;; GNU General Public License for more details. | |
20 | ||
21 | ;; You should have received a copy of the GNU General Public License | |
b578f267 EN |
22 | ;; along with GNU Emacs; see the file COPYING. If not, write to the |
23 | ;; Free Software Foundation, Inc., 59 Temple Place - Suite 330, | |
24 | ;; Boston, MA 02111-1307, USA. | |
7e1dae73 JB |
25 | |
26 | ;;; Commentary: | |
27 | ||
28 | ;; This collection of functions implements lunar phases for calendar.el and | |
29 | ;; diary.el. | |
30 | ||
31 | ;; Based on ``Astronomical Formulae for Calculators,'' 3rd ed., by Jean Meeus, | |
8a45b040 ER |
32 | ;; Willmann-Bell, Inc., 1985 and ``Astronomical Algorithms'' by Jean Meeus, |
33 | ;; Willmann-Bell, Inc., 1991. | |
7e1dae73 JB |
34 | ;; |
35 | ;; WARNING: The calculations will be accurate only to within a few minutes. | |
36 | ||
37 | ;; The author would be delighted to have an astronomically more sophisticated | |
38 | ;; person rewrite the code for the lunar calculations in this file! | |
39 | ||
a96a5fca PE |
40 | ;; Technical details of all the calendrical calculations can be found in |
41 | ;; ``Calendrical Calculations'' by Nachum Dershowitz and Edward M. Reingold, | |
42 | ;; Cambridge University Press (1997). | |
43 | ||
7e1dae73 JB |
44 | ;; Comments, corrections, and improvements should be sent to |
45 | ;; Edward M. Reingold Department of Computer Science | |
46 | ;; (217) 333-6733 University of Illinois at Urbana-Champaign | |
47 | ;; reingold@cs.uiuc.edu 1304 West Springfield Avenue | |
48 | ;; Urbana, Illinois 61801 | |
49 | ||
50 | ;;; Code: | |
51 | ||
52 | (if (fboundp 'atan) | |
53 | (require 'lisp-float-type) | |
3afbc435 | 54 | (error "Lunar calculations impossible since floating point is unavailable")) |
7e1dae73 JB |
55 | |
56 | (require 'solar) | |
57 | ||
58 | (defun lunar-phase-list (month year) | |
59 | "List of lunar phases for three months starting with Gregorian MONTH, YEAR." | |
60 | (let ((end-month month) | |
61 | (end-year year) | |
62 | (start-month month) | |
63 | (start-year year)) | |
64 | (increment-calendar-month end-month end-year 3) | |
65 | (increment-calendar-month start-month start-year -1) | |
66 | (let* ((end-date (list (list end-month 1 end-year))) | |
67 | (start-date (list (list start-month | |
68 | (calendar-last-day-of-month | |
69 | start-month start-year) | |
70 | start-year))) | |
71 | (index (* 4 | |
72 | (truncate | |
73 | (* 12.3685 | |
74 | (+ year | |
75 | ( / (calendar-day-number (list month 1 year)) | |
76 | 366.0) | |
77 | -1900))))) | |
78 | (new-moon (lunar-phase index)) | |
79 | (list)) | |
80 | (while (calendar-date-compare new-moon end-date) | |
81 | (if (calendar-date-compare start-date new-moon) | |
82 | (setq list (append list (list new-moon)))) | |
83 | (setq index (1+ index)) | |
84 | (setq new-moon (lunar-phase index))) | |
85 | list))) | |
86 | ||
87 | (defun lunar-phase (index) | |
88 | "Local date and time of lunar phase INDEX. | |
89 | Integer below INDEX/4 gives the lunation number, counting from Jan 1, 1900; | |
90 | remainder mod 4 gives the phase: 0 new moon, 1 first quarter, 2 full moon, | |
91 | 3 last quarter." | |
b6c0aabf | 92 | (let* ((phase (mod index 4)) |
7e1dae73 JB |
93 | (index (/ index 4.0)) |
94 | (time (/ index 1236.85)) | |
95 | (date (+ (calendar-absolute-from-gregorian '(1 0.5 1900)) | |
96 | 0.75933 | |
97 | (* 29.53058868 index) | |
98 | (* 0.0001178 time time) | |
99 | (* -0.000000155 time time time) | |
100 | (* 0.00033 | |
101 | (solar-sin-degrees (+ 166.56 | |
102 | (* 132.87 time) | |
103 | (* -0.009173 time time)))))) | |
e7bb3aeb | 104 | (sun-anomaly (mod |
7e1dae73 JB |
105 | (+ 359.2242 |
106 | (* 29.105356 index) | |
107 | (* -0.0000333 time time) | |
108 | (* -0.00000347 time time time)) | |
109 | 360.0)) | |
e7bb3aeb | 110 | (moon-anomaly (mod |
7e1dae73 JB |
111 | (+ 306.0253 |
112 | (* 385.81691806 index) | |
113 | (* 0.0107306 time time) | |
114 | (* 0.00001236 time time time)) | |
115 | 360.0)) | |
e7bb3aeb | 116 | (moon-lat (mod |
7e1dae73 JB |
117 | (+ 21.2964 |
118 | (* 390.67050646 index) | |
119 | (* -0.0016528 time time) | |
120 | (* -0.00000239 time time time)) | |
121 | 360.0)) | |
122 | (adjustment | |
123 | (if (memq phase '(0 2)) | |
124 | (+ (* (- 0.1734 (* 0.000393 time)) | |
125 | (solar-sin-degrees sun-anomaly)) | |
126 | (* 0.0021 (solar-sin-degrees (* 2 sun-anomaly))) | |
127 | (* -0.4068 (solar-sin-degrees moon-anomaly)) | |
128 | (* 0.0161 (solar-sin-degrees (* 2 moon-anomaly))) | |
129 | (* -0.0004 (solar-sin-degrees (* 3 moon-anomaly))) | |
130 | (* 0.0104 (solar-sin-degrees (* 2 moon-lat))) | |
131 | (* -0.0051 (solar-sin-degrees (+ sun-anomaly moon-anomaly))) | |
132 | (* -0.0074 (solar-sin-degrees (- sun-anomaly moon-anomaly))) | |
133 | (* 0.0004 (solar-sin-degrees (+ (* 2 moon-lat) sun-anomaly))) | |
134 | (* -0.0004 (solar-sin-degrees (- (* 2 moon-lat) sun-anomaly))) | |
135 | (* -0.0006 (solar-sin-degrees | |
136 | (+ (* 2 moon-lat) moon-anomaly))) | |
137 | (* 0.0010 (solar-sin-degrees (- (* 2 moon-lat) moon-anomaly))) | |
138 | (* 0.0005 (solar-sin-degrees | |
139 | (+ (* 2 moon-anomaly) sun-anomaly)))) | |
140 | (+ (* (- 0.1721 (* 0.0004 time)) | |
141 | (solar-sin-degrees sun-anomaly)) | |
142 | (* 0.0021 (solar-sin-degrees (* 2 sun-anomaly))) | |
143 | (* -0.6280 (solar-sin-degrees moon-anomaly)) | |
144 | (* 0.0089 (solar-sin-degrees (* 2 moon-anomaly))) | |
145 | (* -0.0004 (solar-sin-degrees (* 3 moon-anomaly))) | |
146 | (* 0.0079 (solar-sin-degrees (* 2 moon-lat))) | |
147 | (* -0.0119 (solar-sin-degrees (+ sun-anomaly moon-anomaly))) | |
148 | (* -0.0047 (solar-sin-degrees (- sun-anomaly moon-anomaly))) | |
149 | (* 0.0003 (solar-sin-degrees (+ (* 2 moon-lat) sun-anomaly))) | |
150 | (* -0.0004 (solar-sin-degrees (- (* 2 moon-lat) sun-anomaly))) | |
151 | (* -0.0006 (solar-sin-degrees (+ (* 2 moon-lat) moon-anomaly))) | |
152 | (* 0.0021 (solar-sin-degrees (- (* 2 moon-lat) moon-anomaly))) | |
153 | (* 0.0003 (solar-sin-degrees | |
154 | (+ (* 2 moon-anomaly) sun-anomaly))) | |
155 | (* 0.0004 (solar-sin-degrees | |
156 | (- sun-anomaly (* 2 moon-anomaly)))) | |
157 | (* -0.0003 (solar-sin-degrees | |
158 | (+ (* 2 sun-anomaly) moon-anomaly)))))) | |
159 | (adj (+ 0.0028 | |
160 | (* -0.0004 (solar-cosine-degrees | |
161 | sun-anomaly)) | |
162 | (* 0.0003 (solar-cosine-degrees | |
163 | moon-anomaly)))) | |
164 | (adjustment (cond ((= phase 1) (+ adjustment adj)) | |
165 | ((= phase 2) (- adjustment adj)) | |
166 | (t adjustment))) | |
167 | (date (+ date adjustment)) | |
238c5cc1 PE |
168 | (date (+ date (/ (- calendar-time-zone |
169 | (solar-ephemeris-correction | |
80e48f9f JB |
170 | (extract-calendar-year |
171 | (calendar-gregorian-from-absolute | |
238c5cc1 PE |
172 | (truncate date))))) |
173 | 60.0 24.0))) | |
7e1dae73 | 174 | (time (* 24 (- date (truncate date)))) |
e483c805 | 175 | (date (calendar-gregorian-from-absolute (truncate date))) |
8a45b040 | 176 | (adj (dst-adjust-time date time))) |
e483c805 | 177 | (list (car adj) (apply 'solar-time-string (cdr adj)) phase))) |
7e1dae73 JB |
178 | |
179 | (defun lunar-phase-name (phase) | |
180 | "Name of lunar PHASE. | |
181 | 0 = new moon, 1 = first quarter, 2 = full moon, 3 = last quarter." | |
182 | (cond ((= 0 phase) "New Moon") | |
183 | ((= 1 phase) "First Quarter Moon") | |
184 | ((= 2 phase) "Full Moon") | |
185 | ((= 3 phase) "Last Quarter Moon"))) | |
186 | ||
187 | (defun calendar-phases-of-moon () | |
188 | "Create a buffer with the lunar phases for the current calendar window." | |
189 | (interactive) | |
190 | (message "Computing phases of the moon...") | |
191 | (let ((m1 displayed-month) | |
192 | (y1 displayed-year) | |
193 | (m2 displayed-month) | |
cc4879d2 | 194 | (y2 displayed-year)) |
7e1dae73 JB |
195 | (increment-calendar-month m1 y1 -1) |
196 | (increment-calendar-month m2 y2 1) | |
197 | (set-buffer (get-buffer-create lunar-phases-buffer)) | |
198 | (setq buffer-read-only nil) | |
199 | (calendar-set-mode-line | |
1a380827 RS |
200 | (if (= y1 y2) |
201 | (format "Phases of the Moon from %s to %s, %d%%-" | |
202 | (calendar-month-name m1) (calendar-month-name m2) y2) | |
203 | (format "Phases of the Moon from %s, %d to %s, %d%%-" | |
204 | (calendar-month-name m1) y1 (calendar-month-name m2) y2))) | |
7e1dae73 JB |
205 | (erase-buffer) |
206 | (insert | |
207 | (mapconcat | |
208 | '(lambda (x) | |
209 | (let ((date (car x)) | |
210 | (time (car (cdr x))) | |
211 | (phase (car (cdr (cdr x))))) | |
212 | (concat (calendar-date-string date) | |
213 | ": " | |
214 | (lunar-phase-name phase) | |
215 | " " | |
216 | time))) | |
217 | (lunar-phase-list m1 y1) "\n")) | |
218 | (goto-char (point-min)) | |
219 | (set-buffer-modified-p nil) | |
220 | (setq buffer-read-only t) | |
221 | (display-buffer lunar-phases-buffer) | |
222 | (message "Computing phases of the moon...done"))) | |
223 | ||
224 | ;;;###autoload | |
225 | (defun phases-of-moon (&optional arg) | |
226 | "Display the quarters of the moon for last month, this month, and next month. | |
227 | If called with an optional prefix argument, prompts for month and year. | |
228 | ||
229 | This function is suitable for execution in a .emacs file." | |
230 | (interactive "P") | |
231 | (save-excursion | |
46124264 | 232 | (let* ((date (if arg |
cc4879d2 ER |
233 | (calendar-read-date t) |
234 | (calendar-current-date))) | |
235 | (displayed-month (extract-calendar-month date)) | |
236 | (displayed-year (extract-calendar-year date))) | |
7e1dae73 JB |
237 | (calendar-phases-of-moon)))) |
238 | ||
e0ab9b68 RS |
239 | (defun diary-phases-of-moon (&optional mark) |
240 | "Moon phases diary entry. | |
241 | ||
242 | An optional parameter MARK specifies a face or single-character string to | |
243 | use when highlighting the day in the calendar." | |
7e1dae73 JB |
244 | (let* ((index (* 4 |
245 | (truncate | |
246 | (* 12.3685 | |
247 | (+ (extract-calendar-year date) | |
248 | ( / (calendar-day-number date) | |
249 | 366.0) | |
250 | -1900))))) | |
251 | (phase (lunar-phase index))) | |
252 | (while (calendar-date-compare phase (list date)) | |
253 | (setq index (1+ index)) | |
254 | (setq phase (lunar-phase index))) | |
255 | (if (calendar-date-equal (car phase) date) | |
e0ab9b68 RS |
256 | (cons mark (concat (lunar-phase-name (car (cdr (cdr phase)))) " " |
257 | (car (cdr phase))))))) | |
7e1dae73 | 258 | |
8a45b040 ER |
259 | |
260 | ;; For the Chinese calendar the calculations for the new moon need to be more | |
261 | ;; accurate than those above, so we use more terms in the approximation. | |
262 | ||
263 | (defun lunar-new-moon-time (k) | |
264 | "Astronomical (Julian) day number of K th new moon." | |
265 | (let* ((T (/ k 1236.85)) | |
266 | (T2 (* T T)) | |
267 | (T3 (* T T T)) | |
268 | (T4 (* T2 T2)) | |
269 | (JDE (+ 2451550.09765 | |
270 | (* 29.530588853 k) | |
271 | (* 0.0001337 T2) | |
272 | (* -0.000000150 T3) | |
273 | (* 0.00000000073 T4))) | |
274 | (E (- 1 (* 0.002516 T) (* 0.0000074 T2))) | |
275 | (sun-anomaly (+ 2.5534 | |
276 | (* 29.10535669 k) | |
277 | (* -0.0000218 T2) | |
278 | (* -0.00000011 T3))) | |
279 | (moon-anomaly (+ 201.5643 | |
280 | (* 385.81693528 k) | |
281 | (* 0.0107438 T2) | |
282 | (* 0.00001239 T3) | |
283 | (* -0.000000058 T4))) | |
284 | (moon-argument (+ 160.7108 | |
285 | (* 390.67050274 k) | |
286 | (* -0.0016341 T2) | |
287 | (* -0.00000227 T3) | |
288 | (* 0.000000011 T4))) | |
289 | (omega (+ 124.7746 | |
290 | (* -1.56375580 k) | |
291 | (* 0.0020691 T2) | |
292 | (* 0.00000215 T3))) | |
293 | (A1 (+ 299.77 (* 0.107408 k) (* -0.009173 T2))) | |
294 | (A2 (+ 251.88 (* 0.016321 k))) | |
295 | (A3 (+ 251.83 (* 26.641886 k))) | |
296 | (A4 (+ 349.42 (* 36.412478 k))) | |
297 | (A5 (+ 84.66 (* 18.206239 k))) | |
298 | (A6 (+ 141.74 (* 53.303771 k))) | |
299 | (A7 (+ 207.14 (* 2.453732 k))) | |
300 | (A8 (+ 154.84 (* 7.306860 k))) | |
301 | (A9 (+ 34.52 (* 27.261239 k))) | |
302 | (A10 (+ 207.19 (* 0.121824 k))) | |
303 | (A11 (+ 291.34 (* 1.844379 k))) | |
304 | (A12 (+ 161.72 (* 24.198154 k))) | |
305 | (A13 (+ 239.56 (* 25.513099 k))) | |
306 | (A14 (+ 331.55 (* 3.592518 k))) | |
307 | (correction | |
308 | (+ (* -0.40720 (solar-sin-degrees moon-anomaly)) | |
309 | (* 0.17241 E (solar-sin-degrees sun-anomaly)) | |
310 | (* 0.01608 (solar-sin-degrees (* 2 moon-anomaly))) | |
311 | (* 0.01039 (solar-sin-degrees (* 2 moon-argument))) | |
312 | (* 0.00739 E (solar-sin-degrees (- moon-anomaly sun-anomaly))) | |
313 | (* -0.00514 E (solar-sin-degrees (+ moon-anomaly sun-anomaly))) | |
314 | (* 0.00208 E E (solar-sin-degrees (* 2 sun-anomaly))) | |
315 | (* -0.00111 (solar-sin-degrees | |
316 | (- moon-anomaly (* 2 moon-argument)))) | |
317 | (* -0.00057 (solar-sin-degrees | |
318 | (+ moon-anomaly (* 2 moon-argument)))) | |
319 | (* 0.00056 E (solar-sin-degrees | |
320 | (+ (* 2 moon-anomaly) sun-anomaly))) | |
321 | (* -0.00042 (solar-sin-degrees (* 3 moon-anomaly))) | |
322 | (* 0.00042 E (solar-sin-degrees | |
323 | (+ sun-anomaly (* 2 moon-argument)))) | |
324 | (* 0.00038 E (solar-sin-degrees | |
325 | (- sun-anomaly (* 2 moon-argument)))) | |
326 | (* -0.00024 E (solar-sin-degrees | |
327 | (- (* 2 moon-anomaly) sun-anomaly))) | |
328 | (* -0.00017 (solar-sin-degrees omega)) | |
329 | (* -0.00007 (solar-sin-degrees | |
330 | (+ moon-anomaly (* 2 sun-anomaly)))) | |
331 | (* 0.00004 (solar-sin-degrees | |
332 | (- (* 2 moon-anomaly) (* 2 moon-argument)))) | |
333 | (* 0.00004 (solar-sin-degrees (* 3 sun-anomaly))) | |
334 | (* 0.00003 (solar-sin-degrees (+ moon-anomaly sun-anomaly | |
335 | (* -2 moon-argument)))) | |
336 | (* 0.00003 (solar-sin-degrees | |
337 | (+ (* 2 moon-anomaly) (* 2 moon-argument)))) | |
338 | (* -0.00003 (solar-sin-degrees (+ moon-anomaly sun-anomaly | |
339 | (* 2 moon-argument)))) | |
340 | (* 0.00003 (solar-sin-degrees (- moon-anomaly sun-anomaly | |
341 | (* -2 moon-argument)))) | |
342 | (* -0.00002 (solar-sin-degrees (- moon-anomaly sun-anomaly | |
343 | (* 2 moon-argument)))) | |
344 | (* -0.00002 (solar-sin-degrees | |
345 | (+ (* 3 moon-anomaly) sun-anomaly))) | |
346 | (* 0.00002 (solar-sin-degrees (* 4 moon-anomaly))))) | |
347 | (additional | |
348 | (+ (* 0.000325 (solar-sin-degrees A1)) | |
349 | (* 0.000165 (solar-sin-degrees A2)) | |
350 | (* 0.000164 (solar-sin-degrees A3)) | |
351 | (* 0.000126 (solar-sin-degrees A4)) | |
352 | (* 0.000110 (solar-sin-degrees A5)) | |
353 | (* 0.000062 (solar-sin-degrees A6)) | |
354 | (* 0.000060 (solar-sin-degrees A7)) | |
355 | (* 0.000056 (solar-sin-degrees A8)) | |
356 | (* 0.000047 (solar-sin-degrees A9)) | |
357 | (* 0.000042 (solar-sin-degrees A10)) | |
358 | (* 0.000040 (solar-sin-degrees A11)) | |
359 | (* 0.000037 (solar-sin-degrees A12)) | |
360 | (* 0.000035 (solar-sin-degrees A13)) | |
361 | (* 0.000023 (solar-sin-degrees A14)))) | |
362 | (newJDE (+ JDE correction additional))) | |
363 | (+ newJDE | |
364 | (- (solar-ephemeris-correction | |
365 | (extract-calendar-year | |
366 | (calendar-gregorian-from-absolute | |
367 | (floor (calendar-absolute-from-astro newJDE)))))) | |
368 | (/ calendar-time-zone 60.0 24.0)))) | |
369 | ||
370 | (defun lunar-new-moon-on-or-after (d) | |
371 | "Astronomical (Julian) day number of first new moon on or after astronomical | |
3001419f | 372 | \(Julian) day number d. The fractional part is the time of day. |
8a45b040 ER |
373 | |
374 | The date and time are local time, including any daylight savings rules, | |
375 | as governed by the values of calendar-daylight-savings-starts, | |
376 | calendar-daylight-savings-starts-time, calendar-daylight-savings-ends, | |
377 | calendar-daylight-savings-ends-time, calendar-daylight-time-offset, and | |
378 | calendar-time-zone." | |
379 | (let* ((date (calendar-gregorian-from-absolute | |
380 | (floor (calendar-absolute-from-astro d)))) | |
381 | (year (+ (extract-calendar-year date) | |
382 | (/ (calendar-day-number date) 365.25))) | |
383 | (k (floor (* (- year 2000.0) 12.3685))) | |
384 | (date (lunar-new-moon-time k))) | |
385 | (while (< date d) | |
386 | (setq k (1+ k)) | |
387 | (setq date (lunar-new-moon-time k))) | |
388 | (let* ((a-date (calendar-absolute-from-astro date)) | |
389 | (time (* 24 (- a-date (truncate a-date)))) | |
390 | (date (calendar-gregorian-from-absolute (truncate a-date))) | |
391 | (adj (dst-adjust-time date time))) | |
392 | (calendar-astro-from-absolute | |
393 | (+ (calendar-absolute-from-gregorian (car adj)) | |
394 | (/ (car (cdr adj)) 24.0)))))) | |
395 | ||
7e1dae73 JB |
396 | (provide 'lunar) |
397 | ||
398 | ;;; lunar.el ends here |