Mercurial > hg > xemacs-beta

comparison lisp/calendar/lunar.el @ 0:376386a54a3c r19-14

Find changesets by keywords (author, files, the commit message), revision number or hash, or revset expression.
Import from CVS: tag r19-14
author cvs
date Mon, 13 Aug 2007 08:45:50 +0200
parents
children 0293115a14e9
comparison
equal deleted inserted replaced
-1:000000000000 0:376386a54a3c
1 ;;; lunar.el --- calendar functions for phases of the moon.
2
3 ;; Copyright (C) 1992, 1993 Free Software Foundation, Inc.
4
5 ;; Author: Edward M. Reingold <reingold@cs.uiuc.edu>
6 ;; Keywords: calendar
7 ;; Human-Keywords: moon, lunar phases, calendar, diary
8
9 ;; This file is part of XEmacs.
10
11 ;; XEmacs is free software; you can redistribute it and/or modify it
12 ;; 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
16 ;; XEmacs is distributed in the hope that it will be useful, but
17 ;; WITHOUT ANY WARRANTY; without even the implied warranty of
18 ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
19 ;; General Public License for more details.
20
21 ;; You should have received a copy of the GNU General Public License
22 ;; along with XEmacs; see the file COPYING. If not, write to the Free
23 ;; Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
24
25 ;;; Commentary:
26
27 ;; This collection of functions implements lunar phases for calendar.el and
28 ;; diary.el.
29
30 ;; Based on ``Astronomical Formulae for Calculators,'' 3rd ed., by Jean Meeus,
31 ;; Willmann-Bell, Inc., 1985.
32 ;;
33 ;; WARNING: The calculations will be accurate only to within a few minutes.
34
35 ;; The author would be delighted to have an astronomically more sophisticated
36 ;; person rewrite the code for the lunar calculations in this file!
37
38 ;; Comments, corrections, and improvements should be sent to
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 ;;; Code:
45
46 (if (fboundp 'atan)
47 (require 'lisp-float-type)
48 (error "Lunar calculations impossible since floating point is unavailable."))
49
50 (require 'solar)
51
52 (defun lunar-phase-list (month year)
53 "List of lunar phases for three months starting with Gregorian MONTH, YEAR."
54 (let ((end-month month)
55 (end-year year)
56 (start-month month)
57 (start-year year))
58 (increment-calendar-month end-month end-year 3)
59 (increment-calendar-month start-month start-year -1)
60 (let* ((end-date (list (list end-month 1 end-year)))
61 (start-date (list (list start-month
62 (calendar-last-day-of-month
63 start-month start-year)
64 start-year)))
65 (index (* 4
66 (truncate
67 (* 12.3685
68 (+ year
69 ( / (calendar-day-number (list month 1 year))
70 366.0)
71 -1900)))))
72 (new-moon (lunar-phase index))
73 (list))
74 (while (calendar-date-compare new-moon end-date)
75 (if (calendar-date-compare start-date new-moon)
76 (setq list (append list (list new-moon))))
77 (setq index (1+ index))
78 (setq new-moon (lunar-phase index)))
79 list)))
80
81 (defun lunar-phase (index)
82 "Local date and time of lunar phase INDEX.
83 Integer below INDEX/4 gives the lunation number, counting from Jan 1, 1900;
84 remainder mod 4 gives the phase: 0 new moon, 1 first quarter, 2 full moon,
85 3 last quarter."
86 (let* ((phase (mod index 4))
87 (index (/ index 4.0))
88 (time (/ index 1236.85))
89 (date (+ (calendar-absolute-from-gregorian '(1 0.5 1900))
90 0.75933
91 (* 29.53058868 index)
92 (* 0.0001178 time time)
93 (* -0.000000155 time time time)
94 (* 0.00033
95 (solar-sin-degrees (+ 166.56
96 (* 132.87 time)
97 (* -0.009173 time time))))))
98 (sun-anomaly (mod
99 (+ 359.2242
100 (* 29.105356 index)
101 (* -0.0000333 time time)
102 (* -0.00000347 time time time))
103 360.0))
104 (moon-anomaly (mod
105 (+ 306.0253
106 (* 385.81691806 index)
107 (* 0.0107306 time time)
108 (* 0.00001236 time time time))
109 360.0))
110 (moon-lat (mod
111 (+ 21.2964
112 (* 390.67050646 index)
113 (* -0.0016528 time time)
114 (* -0.00000239 time time time))
115 360.0))
116 (adjustment
117 (if (memq phase '(0 2))
118 (+ (* (- 0.1734 (* 0.000393 time))
119 (solar-sin-degrees sun-anomaly))
120 (* 0.0021 (solar-sin-degrees (* 2 sun-anomaly)))
121 (* -0.4068 (solar-sin-degrees moon-anomaly))
122 (* 0.0161 (solar-sin-degrees (* 2 moon-anomaly)))
123 (* -0.0004 (solar-sin-degrees (* 3 moon-anomaly)))
124 (* 0.0104 (solar-sin-degrees (* 2 moon-lat)))
125 (* -0.0051 (solar-sin-degrees (+ sun-anomaly moon-anomaly)))
126 (* -0.0074 (solar-sin-degrees (- sun-anomaly moon-anomaly)))
127 (* 0.0004 (solar-sin-degrees (+ (* 2 moon-lat) sun-anomaly)))
128 (* -0.0004 (solar-sin-degrees (- (* 2 moon-lat) sun-anomaly)))
129 (* -0.0006 (solar-sin-degrees
130 (+ (* 2 moon-lat) moon-anomaly)))
131 (* 0.0010 (solar-sin-degrees (- (* 2 moon-lat) moon-anomaly)))
132 (* 0.0005 (solar-sin-degrees
133 (+ (* 2 moon-anomaly) sun-anomaly))))
134 (+ (* (- 0.1721 (* 0.0004 time))
135 (solar-sin-degrees sun-anomaly))
136 (* 0.0021 (solar-sin-degrees (* 2 sun-anomaly)))
137 (* -0.6280 (solar-sin-degrees moon-anomaly))
138 (* 0.0089 (solar-sin-degrees (* 2 moon-anomaly)))
139 (* -0.0004 (solar-sin-degrees (* 3 moon-anomaly)))
140 (* 0.0079 (solar-sin-degrees (* 2 moon-lat)))
141 (* -0.0119 (solar-sin-degrees (+ sun-anomaly moon-anomaly)))
142 (* -0.0047 (solar-sin-degrees (- sun-anomaly moon-anomaly)))
143 (* 0.0003 (solar-sin-degrees (+ (* 2 moon-lat) sun-anomaly)))
144 (* -0.0004 (solar-sin-degrees (- (* 2 moon-lat) sun-anomaly)))
145 (* -0.0006 (solar-sin-degrees (+ (* 2 moon-lat) moon-anomaly)))
146 (* 0.0021 (solar-sin-degrees (- (* 2 moon-lat) moon-anomaly)))
147 (* 0.0003 (solar-sin-degrees
148 (+ (* 2 moon-anomaly) sun-anomaly)))
149 (* 0.0004 (solar-sin-degrees
150 (- sun-anomaly (* 2 moon-anomaly))))
151 (* -0.0003 (solar-sin-degrees
152 (+ (* 2 sun-anomaly) moon-anomaly))))))
153 (adj (+ 0.0028
154 (* -0.0004 (solar-cosine-degrees
155 sun-anomaly))
156 (* 0.0003 (solar-cosine-degrees
157 moon-anomaly))))
158 (adjustment (cond ((= phase 1) (+ adjustment adj))
159 ((= phase 2) (- adjustment adj))
160 (t adjustment)))
161 (date (+ date adjustment))
162 (date (+ date (/ (- calendar-time-zone
163 (solar-ephemeris-correction
164 (extract-calendar-year
165 (calendar-gregorian-from-absolute
166 (truncate date)))))
167 60.0 24.0)))
168 (time (* 24 (- date (truncate date))))
169 (date (calendar-gregorian-from-absolute (truncate date)))
170 (adj (solar-adj-time-for-dst date time)))
171 (list (car adj) (apply 'solar-time-string (cdr adj)) phase)))
172
173 (defun lunar-phase-name (phase)
174 "Name of lunar PHASE.
175 0 = new moon, 1 = first quarter, 2 = full moon, 3 = last quarter."
176 (cond ((= 0 phase) "New Moon")
177 ((= 1 phase) "First Quarter Moon")
178 ((= 2 phase) "Full Moon")
179 ((= 3 phase) "Last Quarter Moon")))
180
181 (defun calendar-phases-of-moon ()
182 "Create a buffer with the lunar phases for the current calendar window."
183 (interactive)
184 (message "Computing phases of the moon...")
185 (let ((m1 displayed-month)
186 (y1 displayed-year)
187 (m2 displayed-month)
188 (y2 displayed-year))
189 (increment-calendar-month m1 y1 -1)
190 (increment-calendar-month m2 y2 1)
191 (set-buffer (get-buffer-create lunar-phases-buffer))
192 (setq buffer-read-only nil)
193 (calendar-set-mode-line
194 (if (= y1 y2)
195 (format "Phases of the Moon from %s to %s, %d%%-"
196 (calendar-month-name m1) (calendar-month-name m2) y2)
197 (format "Phases of the Moon from %s, %d to %s, %d%%-"
198 (calendar-month-name m1) y1 (calendar-month-name m2) y2)))
199 (erase-buffer)
200 (insert
201 (mapconcat
202 '(lambda (x)
203 (let ((date (car x))
204 (time (car (cdr x)))
205 (phase (car (cdr (cdr x)))))
206 (concat (calendar-date-string date)
207 ": "
208 (lunar-phase-name phase)
209 " "
210 time)))
211 (lunar-phase-list m1 y1) "\n"))
212 (goto-char (point-min))
213 (set-buffer-modified-p nil)
214 (setq buffer-read-only t)
215 (display-buffer lunar-phases-buffer)
216 (message "Computing phases of the moon...done")))
217
218 ;;;###autoload
219 (defun phases-of-moon (&optional arg)
220 "Display the quarters of the moon for last month, this month, and next month.
221 If called with an optional prefix argument, prompts for month and year.
222
223 This function is suitable for execution in a .emacs file."
224 (interactive "P")
225 (save-excursion
226 (let* ((date (if arg
227 (calendar-read-date t)
228 (calendar-current-date)))
229 (displayed-month (extract-calendar-month date))
230 (displayed-year (extract-calendar-year date)))
231 (calendar-phases-of-moon))))
232
233 (defun diary-phases-of-moon ()
234 "Moon phases diary entry."
235 (let* ((index (* 4
236 (truncate
237 (* 12.3685
238 (+ (extract-calendar-year date)
239 ( / (calendar-day-number date)
240 366.0)
241 -1900)))))
242 (phase (lunar-phase index)))
243 (while (calendar-date-compare phase (list date))
244 (setq index (1+ index))
245 (setq phase (lunar-phase index)))
246 (if (calendar-date-equal (car phase) date)
247 (concat (lunar-phase-name (car (cdr (cdr phase)))) " "
248 (car (cdr phase))))))
249
250 (provide 'lunar)
251
252 ;;; lunar.el ends here