[bpt/emacs.git] / lisp / calendar / lunar.el

;;; lunar.el --- calendar functions for phases of the moon.

;; Copyright (C) 1992, 1993 Free Software Foundation, Inc.

;; Author: Edward M. Reingold <reingold@cs.uiuc.edu>
;; Keywords: calendar
;; Human-Keywords: moon, lunar phases, calendar, diary

;; This file is part of GNU Emacs.

;; 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.

;; GNU Emacs is distributed in the hope that it will be useful,
;; 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
;; along with GNU Emacs; see the file COPYING.  If not, write to
;; the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.

;;; Commentary:

;; This collection of functions implements lunar phases for calendar.el and
;; diary.el.

;; Based on ``Astronomical Formulae for Calculators,'' 3rd ed., by Jean Meeus,
;; Willmann-Bell, Inc., 1985.
;;
;; WARNING: The calculations will be accurate only to within a few minutes.

;; The author would be delighted to have an astronomically more sophisticated
;; person rewrite the code for the lunar calculations in this file!

;; Comments, corrections, and improvements should be sent to
;;  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

;;; Code:

(if (fboundp 'atan)
    (require 'lisp-float-type)
  (error "Lunar calculations impossible since floating point is unavailable."))

(require 'solar)

(defun lunar-phase-list (month year)
  "List of lunar phases for three months starting with Gregorian MONTH, YEAR."
  (let ((end-month month)
        (end-year year)
        (start-month month)
        (start-year year))
    (increment-calendar-month end-month end-year 3)
    (increment-calendar-month start-month start-year -1)
    (let* ((end-date (list (list end-month 1 end-year)))
           (start-date (list (list start-month 
                                   (calendar-last-day-of-month
                                    start-month start-year)
                                   start-year)))
           (index (* 4
                     (truncate
                      (* 12.3685
                         (+ year
                            ( / (calendar-day-number (list month 1 year))
                                366.0)
                            -1900)))))
           (new-moon (lunar-phase index))
           (list))
      (while (calendar-date-compare new-moon end-date)
        (if (calendar-date-compare start-date new-moon)
            (setq list (append list (list new-moon))))
        (setq index (1+ index))
        (setq new-moon (lunar-phase index)))
      list)))

(defun lunar-phase (index)
  "Local date and time of lunar phase INDEX.
Integer below INDEX/4 gives the lunation number, counting from Jan 1, 1900;
remainder mod 4 gives the phase: 0 new moon, 1 first quarter, 2 full moon,
3 last quarter."
  (let* ((phase (mod index 4))
         (index (/ index 4.0))
         (time (/ index 1236.85))
         (date (+ (calendar-absolute-from-gregorian '(1 0.5 1900))
                  0.75933
                  (* 29.53058868 index)
                  (* 0.0001178 time time)
                  (* -0.000000155 time time time)
                  (* 0.00033
                     (solar-sin-degrees (+ 166.56
                                           (* 132.87 time)
                                           (* -0.009173 time time))))))
         (sun-anomaly (mod
                       (+ 359.2242
                          (* 29.105356 index)
                          (* -0.0000333 time time)
                          (* -0.00000347 time time time))
                       360.0))
         (moon-anomaly (mod
                        (+ 306.0253
                           (* 385.81691806 index)
                           (* 0.0107306 time time)
                           (* 0.00001236 time time time))
                        360.0))
         (moon-lat (mod
                    (+ 21.2964
                       (* 390.67050646 index)
                       (* -0.0016528 time time)
                       (* -0.00000239 time time time))
                    360.0))
         (adjustment
          (if (memq phase '(0 2))
              (+ (* (- 0.1734 (* 0.000393 time))
                    (solar-sin-degrees sun-anomaly))
                 (* 0.0021 (solar-sin-degrees (* 2 sun-anomaly)))
                 (* -0.4068 (solar-sin-degrees moon-anomaly))
                 (* 0.0161 (solar-sin-degrees (* 2 moon-anomaly)))
                 (* -0.0004 (solar-sin-degrees (* 3 moon-anomaly)))
                 (* 0.0104 (solar-sin-degrees (* 2 moon-lat)))
                 (* -0.0051 (solar-sin-degrees (+ sun-anomaly moon-anomaly)))
                 (* -0.0074 (solar-sin-degrees (- sun-anomaly moon-anomaly)))
                 (* 0.0004 (solar-sin-degrees (+ (* 2 moon-lat) sun-anomaly)))
                 (* -0.0004 (solar-sin-degrees (- (* 2 moon-lat) sun-anomaly)))
                 (* -0.0006 (solar-sin-degrees
                             (+ (* 2 moon-lat) moon-anomaly)))
                 (* 0.0010 (solar-sin-degrees (- (* 2 moon-lat) moon-anomaly)))
                 (* 0.0005 (solar-sin-degrees
                            (+ (* 2 moon-anomaly) sun-anomaly))))
            (+ (* (- 0.1721 (* 0.0004 time))
                  (solar-sin-degrees sun-anomaly))
               (* 0.0021 (solar-sin-degrees (* 2 sun-anomaly)))
               (* -0.6280 (solar-sin-degrees moon-anomaly))
               (* 0.0089 (solar-sin-degrees (* 2 moon-anomaly)))
               (* -0.0004 (solar-sin-degrees (* 3 moon-anomaly)))
               (* 0.0079 (solar-sin-degrees (* 2 moon-lat)))
               (* -0.0119 (solar-sin-degrees (+ sun-anomaly moon-anomaly)))
               (* -0.0047 (solar-sin-degrees (- sun-anomaly moon-anomaly)))
               (* 0.0003 (solar-sin-degrees (+ (* 2 moon-lat) sun-anomaly)))
               (* -0.0004 (solar-sin-degrees (- (* 2 moon-lat) sun-anomaly)))
               (* -0.0006 (solar-sin-degrees (+ (* 2 moon-lat) moon-anomaly)))
               (* 0.0021 (solar-sin-degrees (- (* 2 moon-lat) moon-anomaly)))
               (* 0.0003 (solar-sin-degrees
                          (+ (* 2 moon-anomaly) sun-anomaly)))
               (* 0.0004 (solar-sin-degrees
                          (- sun-anomaly (* 2 moon-anomaly))))
               (* -0.0003 (solar-sin-degrees
                          (+ (* 2 sun-anomaly) moon-anomaly))))))
         (adj (+ 0.0028
                 (* -0.0004 (solar-cosine-degrees
                             sun-anomaly))
                 (* 0.0003 (solar-cosine-degrees
                            moon-anomaly))))
         (adjustment (cond ((= phase 1) (+ adjustment adj))
                           ((= phase 2) (- adjustment adj))
                           (t adjustment)))
         (date (+ date adjustment))
	 (date (+ date (/ (- calendar-time-zone
			     (solar-ephemeris-correction
                              (extract-calendar-year
                               (calendar-gregorian-from-absolute
                                (truncate date)))))
			  60.0 24.0)))
         (time (* 24 (- date (truncate date))))
	 (date (calendar-gregorian-from-absolute (truncate date))))
    (list date (solar-time-string time date) phase)))

(defun lunar-phase-name (phase)
  "Name of lunar PHASE.
0 = new moon, 1 = first quarter, 2 = full moon, 3 = last quarter."
  (cond ((= 0 phase) "New Moon")
        ((= 1 phase) "First Quarter Moon")
        ((= 2 phase) "Full Moon")
        ((= 3 phase) "Last Quarter Moon")))

(defun calendar-phases-of-moon ()
  "Create a buffer with the lunar phases for the current calendar window."
  (interactive)
  (message "Computing phases of the moon...")
  (let ((m1 displayed-month)
        (y1 displayed-year)
        (m2 displayed-month)
        (y2 displayed-year)
        (lunar-phases-buffer "*Phases of Moon*"))
    (increment-calendar-month m1 y1 -1)
    (increment-calendar-month m2 y2 1)
    (set-buffer (get-buffer-create lunar-phases-buffer))
    (setq buffer-read-only nil)
    (calendar-set-mode-line
     (if (= y1 y2)
         (format "Phases of the Moon from %s to %s, %d%%-"
                 (calendar-month-name m1) (calendar-month-name m2) y2)
       (format "Phases of the Moon from %s, %d to %s, %d%%-"
               (calendar-month-name m1) y1 (calendar-month-name m2) y2)))
    (erase-buffer)
    (insert
     (mapconcat
      '(lambda (x)
         (let ((date (car x))
               (time (car (cdr x)))
               (phase (car (cdr (cdr x)))))
           (concat (calendar-date-string date)
                   ": "
                   (lunar-phase-name phase)
                   " "
                   time)))
      (lunar-phase-list m1 y1) "\n"))
    (goto-char (point-min))
    (set-buffer-modified-p nil)
    (setq buffer-read-only t)
    (display-buffer lunar-phases-buffer)
    (message "Computing phases of the moon...done")))

;;;###autoload
(defun phases-of-moon (&optional arg)
  "Display the quarters of the moon for last month, this month, and next month.
If called with an optional prefix argument, prompts for month and year.

This function is suitable for execution in a .emacs file."
  (interactive "P")
  (save-excursion
    (let* ((completion-ignore-case t)
           (date (calendar-current-date))
           (displayed-month
            (if arg
                (cdr (assoc
                      (capitalize
                       (completing-read
                        "Month name: "
                        (mapcar 'list (append calendar-month-name-array nil))
                        nil t))
                      (calendar-make-alist calendar-month-name-array)))
              (extract-calendar-month date)))
           (displayed-year
            (if arg
                (calendar-read
                 "Year (>0): "
                 '(lambda (x) (> x 0))
                 (int-to-string
                  (extract-calendar-year (calendar-current-date))))
              (extract-calendar-year date))))
      (calendar-phases-of-moon))))

(defun diary-phases-of-moon ()
  "Moon phases diary entry."
  (let* ((index (* 4
                   (truncate
                    (* 12.3685
                       (+ (extract-calendar-year date)
                          ( / (calendar-day-number date)
                              366.0)
                          -1900)))))
         (phase (lunar-phase index)))
    (while (calendar-date-compare phase (list date))
      (setq index (1+ index))
      (setq phase (lunar-phase index)))
    (if (calendar-date-equal (car phase) date)
        (concat (lunar-phase-name (car (cdr (cdr phase)))) " "
                (car (cdr phase))))))

(provide 'lunar)

;;; lunar.el ends here
Commit	Line	Data
7e1dae73 JB	1	;;; lunar.el --- calendar functions for phases of the moon.
7e1dae73 JB	2
238c5cc1	3	;; Copyright (C) 1992, 1993 Free Software Foundation, Inc.
7e1dae73 JB	4
7e1dae73 JB	5	;; Author: Edward M. Reingold <reingold@cs.uiuc.edu>
e9571d2a ER	6	;; Keywords: calendar
e9571d2a ER	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
	22	;; along with GNU Emacs; see the file COPYING. If not, write to
	23	;; the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
7e1dae73 JB	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."
b6c0aabf	86	(let* ((phase (mod index 4))
7e1dae73 JB	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))))))
e7bb3aeb	98	(sun-anomaly (mod
7e1dae73 JB	99	(+ 359.2242
	100	(* 29.105356 index)
	101	(* -0.0000333 time time)
	102	(* -0.00000347 time time time))
	103	360.0))
e7bb3aeb	104	(moon-anomaly (mod
7e1dae73 JB	105	(+ 306.0253
	106	(* 385.81691806 index)
	107	(* 0.0107306 time time)
	108	(* 0.00001236 time time time))
	109	360.0))
e7bb3aeb	110	(moon-lat (mod
7e1dae73 JB	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))
238c5cc1 PE	162	(date (+ date (/ (- calendar-time-zone
238c5cc1 PE	163	(solar-ephemeris-correction
80e48f9f JB	164	(extract-calendar-year
80e48f9f JB	165	(calendar-gregorian-from-absolute
238c5cc1 PE	166	(truncate date)))))
238c5cc1 PE	167	60.0 24.0)))
7e1dae73	168	(time (* 24 (- date (truncate date))))
80e48f9f JB	169	(date (calendar-gregorian-from-absolute (truncate date))))
80e48f9f JB	170	(list date (solar-time-string time date) phase)))
7e1dae73 JB	171
	172	(defun lunar-phase-name (phase)
	173	"Name of lunar PHASE.
	174	0 = new moon, 1 = first quarter, 2 = full moon, 3 = last quarter."
	175	(cond ((= 0 phase) "New Moon")
	176	((= 1 phase) "First Quarter Moon")
	177	((= 2 phase) "Full Moon")
	178	((= 3 phase) "Last Quarter Moon")))
	179
	180	(defun calendar-phases-of-moon ()
	181	"Create a buffer with the lunar phases for the current calendar window."
	182	(interactive)
	183	(message "Computing phases of the moon...")
	184	(let ((m1 displayed-month)
	185	(y1 displayed-year)
	186	(m2 displayed-month)
	187	(y2 displayed-year)
	188	(lunar-phases-buffer "Phases of Moon"))
	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
1a380827 RS	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)))
7e1dae73 JB	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* ((completion-ignore-case t)
	227	(date (calendar-current-date))
	228	(displayed-month
	229	(if arg
	230	(cdr (assoc
	231	(capitalize
	232	(completing-read
	233	"Month name: "
	234	(mapcar 'list (append calendar-month-name-array nil))
	235	nil t))
	236	(calendar-make-alist calendar-month-name-array)))
	237	(extract-calendar-month date)))
	238	(displayed-year
	239	(if arg
	240	(calendar-read
	241	"Year (>0): "
	242	'(lambda (x) (> x 0))
	243	(int-to-string
	244	(extract-calendar-year (calendar-current-date))))
	245	(extract-calendar-year date))))
	246	(calendar-phases-of-moon))))
	247
	248	(defun diary-phases-of-moon ()
	249	"Moon phases diary entry."
	250	(let* ((index (* 4
	251	(truncate
	252	(* 12.3685
	253	(+ (extract-calendar-year date)
	254	( / (calendar-day-number date)
	255	366.0)
	256	-1900)))))
	257	(phase (lunar-phase index)))
	258	(while (calendar-date-compare phase (list date))
	259	(setq index (1+ index))
	260	(setq phase (lunar-phase index)))
	261	(if (calendar-date-equal (car phase) date)
	262	(concat (lunar-phase-name (car (cdr (cdr phase)))) " "
263	(car (cdr phase))))))
264
265	(provide 'lunar)
266
267	;;; lunar.el ends here