Commit 75af4a4a authored by Edward M. Reingold's avatar Edward M. Reingold
Browse files

Added code to support Chinese calendar. Minor fixes as well.

parent 8a45b040
;;; solar.el --- calendar functions for solar events.
;; Copyright (C) 1992, 1993 Free Software Foundation, Inc.
;; Copyright (C) 1992, 1993, 1995 Free Software Foundation, Inc.
;; Author: Edward M. Reingold <reingold@cs.uiuc.edu>
;; Keywords: calendar
......@@ -30,9 +30,11 @@
;; eqinoxes/solstices.
;; Based on the ``Almanac for Computers 1984,'' prepared by the Nautical
;; Almanac Office, United States Naval Observatory, Washington, 1984 and
;; on ``Astronomical Formulae for Calculators,'' 3rd ed., by Jean Meeus,
;; Willmann-Bell, Inc., 1985.
;; Almanac Office, United States Naval Observatory, Washington, 1984, on
;; ``Astronomical Formulae for Calculators,'' 3rd ed., by Jean Meeus,
;; Willmann-Bell, Inc., 1985, and on ``Astronomical Algorithms'' by Jean
;; Meeus, Willmann-Bell, Inc., 1991.
;;
;; WARNINGS:
;; 1. SUNRISE/SUNSET calculations will be accurate only to +/- 2 minutes.
......@@ -84,7 +86,7 @@ sufficient), + north, - south, such as 40.7 for New York City, or the value
can be a vector [degrees minutes north/south] such as [40 50 north] for New
York City.
This variable should be set in `site-init.el'.")
This variable should be set in site-local.el.")
;;;###autoload
(defvar calendar-longitude nil
......@@ -95,7 +97,7 @@ sufficient), + east, - west, such as -73.9 for New York City, or the value
can be a vector [degrees minutes east/west] such as [73 55 west] for New
York City.
This variable should be set in `site-init.el'.")
This variable should be set in site-local.el.")
(defsubst calendar-latitude ()
"Convert calendar-latitude to a signed decimal fraction, if needed."
......@@ -139,7 +141,7 @@ This variable should be set in `site-init.el'.")
For example, \"New York City\". Default value is just the latitude, longitude
pair.
This variable should be set in `site-init.el'.")
This variable should be set in site-local.el.")
(defvar solar-n-hemi-seasons
'("Vernal Equinox" "Summer Solstice" "Autumnal Equinox" "Winter Solstice")
......@@ -173,13 +175,13 @@ Returns nil if nothing was entered."
(string-to-int x))))
(defsubst solar-sin-degrees (x)
(sin (degrees-to-radians x)))
(sin (degrees-to-radians (mod x 360.0))))
(defsubst solar-cosine-degrees (x)
(cos (degrees-to-radians x)))
(cos (degrees-to-radians (mod x 360.0))))
(defun solar-tangent-degrees (x)
(tan (degrees-to-radians x)))
(defsubst solar-tangent-degrees (x)
(tan (degrees-to-radians (mod x 360.0))))
(defun solar-xy-to-quadrant (x y)
"Determines the quadrant of the point X, Y."
......@@ -316,60 +318,8 @@ that location on that day."
(+ (- local-mean-sunset (solar-degrees-to-hours (calendar-longitude)))
(/ calendar-time-zone 60.0))))))
(defun solar-adj-time-for-dst (date time &optional style)
"Adjust decimal fraction standard TIME on DATE to account for dst.
Returns a list (date adj-time zone) where `date' and `time' are the values
adjusted for `zone'; here `date' is a list (month day year), `time' is a
decimal fraction time, and `zone' is a string.
Optional parameter STYLE forces the result time to be standard time when its
value is 'standard and daylight savings time (if available) when its value is
'daylight.
Conversion to daylight savings time is done according to
`calendar-daylight-savings-starts', `calendar-daylight-savings-ends',
`calendar-daylight-savings-starts-time',
`calendar-daylight-savings-ends-time', and
`calendar-daylight-savings-offset'."
(let* ((year (extract-calendar-year date))
(rounded-abs-date (+ (calendar-absolute-from-gregorian date)
(/ (round (* 60 time)) 60.0 24.0)))
(dst-starts (and calendar-daylight-savings-starts
(+ (calendar-absolute-from-gregorian
(eval calendar-daylight-savings-starts))
(/ calendar-daylight-savings-starts-time
60.0 24.0))))
(dst-ends (and calendar-daylight-savings-ends
(+ (calendar-absolute-from-gregorian
(eval calendar-daylight-savings-ends))
(/ (- calendar-daylight-savings-ends-time
calendar-daylight-time-offset)
60.0 24.0))))
(dst (and (not (eq style 'standard))
(or (eq style 'daylight)
(and dst-starts dst-ends
(or (and (< dst-starts dst-ends);; northern hemi.
(<= dst-starts rounded-abs-date)
(< rounded-abs-date dst-ends))
(and (< dst-ends dst-starts);; southern hemi.
(or (< rounded-abs-date dst-ends)
(<= dst-starts rounded-abs-date)))))
(and dst-starts (not dst-ends)
(<= dst-starts rounded-abs-date))
(and dst-ends (not dst-starts)
(< rounded-abs-date dst-ends)))))
(time-zone (if dst
calendar-daylight-time-zone-name
calendar-standard-time-zone-name))
(time (+ rounded-abs-date
(if dst (/ calendar-daylight-time-offset 24.0 60.0) 0))))
(list (calendar-gregorian-from-absolute (truncate time))
(* 24.0 (- time (truncate time)))
time-zone)))
(defun solar-time-string (time time-zone)
"Printable form for decimal fraction TIME on DATE.
"Printable form for decimal fraction TIME in TIME-ZONE.
Format used is given by `calendar-time-display-form'."
(let* ((time (round (* 60 time)))
(24-hours (/ time 60))
......@@ -382,9 +332,9 @@ Format used is given by `calendar-time-display-form'."
(defun solar-sunrise-sunset (date)
"String giving local times of sunrise and sunset on Gregorian DATE."
(let* ((rise (solar-sunrise date))
(adj-rise (if rise (solar-adj-time-for-dst date rise)))
(adj-rise (if rise (dst-adjust-time date rise)))
(set (solar-sunset date))
(adj-set (if set (solar-adj-time-for-dst date set))))
(adj-set (if set (dst-adjust-time date set))))
(format "%s, %s at %s"
(if (and rise (calendar-date-equal date (car adj-rise)))
(concat "Sunrise " (apply 'solar-time-string (cdr adj-rise)))
......@@ -394,59 +344,148 @@ Format used is given by `calendar-time-display-form'."
"no sunset")
(eval calendar-location-name))))
(defun solar-apparent-longitude-of-sun (date)
"Apparent longitude of the sun on Gregorian DATE."
(let* ((time (/ (- (calendar-absolute-from-gregorian date)
(calendar-absolute-from-gregorian '(1 0.5 1900)))
36525))
(l (+ 279.69668
(* 36000.76892 time)
(* 0.0003025 time time)))
(m (+ 358.47583
(* 35999.04975 time)
(* -0.000150 time time)
(* -0.0000033 time time time)))
(c (+ (* (+ 1.919460
(* -0.004789 time)
(* -0.000014 time time))
(solar-sin-degrees m))
(* (+ 0.020094
(* -0.000100 time))
(solar-sin-degrees (* 2 m)))
(* 0.000293
(solar-sin-degrees (* 3 m)))))
(L (+ l c))
(omega (+ 259.18
(* -1934.142 time)))
(app (+ L
-0.00569
(* -0.00479
(solar-sin-degrees omega)))))
app))
(defun solar-date-next-longitude (d l)
"First moment on or after Julian day number D when sun's longitude is a
multiple of L degrees at calendar-location-name with that location's
local time (including any daylight savings rules).
L must be an integer divisor of 360.
Result is in local time expressed astronomical (Julian) day numbers.
The values of calendar-daylight-savings-starts,
calendar-daylight-savings-starts-time, calendar-daylight-savings-ends,
calendar-daylight-savings-ends-time, calendar-daylight-time-offset, and
calendar-time-zone are used to interpret local time."
(let* ((long)
(start d)
(start-long (solar-longitude d))
(next (mod (* l (1+ (floor (/ start-long l)))) 360))
(end (+ d (* (/ l 360.0) 400)))
(end-long (solar-longitude end)))
(while ;; bisection search for nearest minute
(< 0.00001 (- end start))
;; start <= d < end
;; start-long <= next < end-long when next != 0
;; when next = 0, we look for the discontinuity (start-long is near 360
;; and end-long is small (less than l).
(setq d (/ (+ start end) 2.0))
(setq long (solar-longitude d))
(if (or (and (/= next 0) (< long next))
(and (= next 0) (< l long)))
(progn
(setq start d)
(setq start-long long))
(setq end d)
(setq end-long long)))
(/ (+ start end) 2.0)))
(defun solar-longitude (d)
"Longitude of sun on astronomical (Julian) day number D.
Accurary is about 0.01 degree (about 365.25*24*60*0.01/360 = 15 minutes).
The values of calendar-daylight-savings-starts,
calendar-daylight-savings-starts-time, calendar-daylight-savings-ends,
calendar-daylight-savings-ends-time, calendar-daylight-time-offset, and
calendar-time-zone are used to interpret local time."
(let* ((a-d (calendar-absolute-from-astro d))
(date (calendar-gregorian-from-absolute (floor a-d)))
(time (* 24 (- a-d (truncate a-d))))
(rounded-abs-date (+ (calendar-absolute-from-gregorian date)
(/ (round (* 60 time)) 60.0 24.0)))
;; get local standard time
(a-d (- rounded-abs-date
(if (dst-in-effect rounded-abs-date)
(/ calendar-daylight-time-offset 24.0 60.0) 0)))
;; get Universal Time
(a-d (- a-d (/ calendar-time-zone 60.0 24.0)))
(date (calendar-astro-from-absolute a-d))
;; get Ephemeris Time
(date (+ date (solar-ephemeris-correction
(extract-calendar-year
(calendar-gregorian-from-absolute
(floor
(calendar-absolute-from-astro
date)))))))
(T (/ (- date 2451545.0) 36525.0))
(Lo (mod (+ 280.46645 (* 36000.76983 T) (* 0.0003032 T T)) 360.0))
(M (mod (+ 357.52910
(* 35999.05030 T)
(* -0.0001559 T T)
(* -0.00000048 T T T))
360.0))
(e (+ 0.016708617 (* -0.000042037 T) (* -0.0000001236 T T)))
(C (+ (* (+ 1.914600 (* -0.004817 T) (* -0.000014 T T))
(solar-sin-degrees M))
(* (+ 0.019993 (* -0.000101 T)) (solar-sin-degrees (* 2 M)))
(* 0.000290 (solar-sin-degrees (* 3 M)))))
(true-longitude (+ Lo C))
(omega (+ 125.04 (* -1934.136 T)))
(apparent-longitude (mod
(+ true-longitude
-0.00569
(* -0.00478 (solar-sin-degrees omega)))
360.0)))
apparent-longitude))
(defun solar-ephemeris-correction (year)
"Difference in minutes between Ephemeris time and UTC in YEAR.
Value is only an approximation."
(let ((T (/ (- year 1900) 100.0)))
(+ 0.41 (* 1.2053 T) (* 0.4992 T T))))
(defun solar-equinoxes/solstices (k year)
"Date of equinox/solstice K for YEAR. K=0, spring equinox; K=1, summer
solstice; K=2, fall equinox; K=3, winter solstice. Accurate to within
several minutes."
(let ((date (list (+ 3 (* k 3)) 21 year))
app
(correction 1000))
(while (> correction 0.00001)
(setq app (mod (solar-apparent-longitude-of-sun date) 360))
(setq correction (* 58 (solar-sin-degrees (- (* k 90) app))))
(setq date (list (extract-calendar-month date)
(+ (extract-calendar-day date) correction)
year)))
(list (extract-calendar-month date)
(+ (extract-calendar-day date) (/ calendar-time-zone 60.0 24.0)
(- (/ (solar-ephemeris-correction year) 60.0 24.0)))
year)))
"Ephemeris time minus Universal Time at astronomical (Julian) day D.
Result is in days For the years 1800-1987, the maximum error is 1.9 seconds.
For the other years, the maximum error is about 30 seconds."
(cond ((and (<= 1988 year) (< year 2020))
(/ (+ year -2000 67.0) 60.0 60.0 24.0))
((and (<= 1900 year) (< year 1988))
(let* ((theta (/ (- (calendar-astro-from-absolute
(calendar-absolute-from-gregorian
(list 7 1 year)))
(calendar-astro-from-absolute
(calendar-absolute-from-gregorian
'(1 1 1900))))
36525.0))
(theta2 (* theta theta))
(theta3 (* theta2 theta))
(theta4 (* theta2 theta2))
(theta5 (* theta3 theta2)))
(+ -0.00002
(* 0.000297 theta)
(* 0.025184 theta2)
(* -0.181133 theta3)
(* 0.553040 theta4)
(* -0.861938 theta5)
(* 0.677066 theta3 theta3)
(* -0.212591 theta4 theta3))))
((and (<= 1800 year) (< year 1900))
(let* ((theta (/ (- (calendar-astro-from-absolute
(calendar-absolute-from-gregorian
(list 7 1 year)))
(calendar-astro-from-absolute
(calendar-absolute-from-gregorian
'(1 1 1900))))
36525.0))
(theta2 (* theta theta))
(theta3 (* theta2 theta))
(theta4 (* theta2 theta2))
(theta5 (* theta3 theta2)))
(+ -0.000009
(* 0.003844 theta)
(* 0.083563 theta2)
(* 0.865736 theta3)
(* 4.867575 theta4)
(* 15.845535 theta5)
(* 31.332267 theta3 theta3)
(* 38.291999 theta4 theta3)
(* 28.316289 theta4 theta4)
(* 11.636204 theta4 theta5)
(* 2.043794 theta5 theta5))))
((and (<= 1620 year) (< year 1800))
(let ((x (/ (- year 1600) 10.0)))
(/ (+ (* 2.19167 x x) (* -40.675 x) 196.58333) 60.0 60.0 24.0)))
(t (let* ((tmp (- (calendar-astro-from-absolute
(calendar-absolute-from-gregorian
(list 1 1 year)))
2382148))
(second (- (/ (* tmp tmp) 41048480.0) 15)))
(/ second 60.0 60.0 24.0)))))
;;;###autoload
(defun sunrise-sunset (&optional arg)
......@@ -545,7 +584,7 @@ No diary entry if there is no sunset on that date."
(if (= (% (calendar-absolute-from-gregorian date) 7) 5);; Friday
(let* ((sunset (solar-sunset date))
(light (if sunset
(solar-adj-time-for-dst
(dst-adjust-time
date
(- sunset (/ 18.0 60.0))))))
(if (and light (calendar-date-equal date (car light)))
......@@ -569,19 +608,25 @@ Requires floating point."
(if calendar-time-zone calendar-daylight-savings-ends))
(calendar-time-zone (if calendar-time-zone calendar-time-zone 0))
(k (1- (/ m 3)))
(date (solar-equinoxes/solstices k y))
(s-hemi (and calendar-latitude (< (calendar-latitude) 0)))
(day (extract-calendar-day date))
(adj (solar-adj-time-for-dst
(list (extract-calendar-month date)
(truncate day)
(extract-calendar-year date))
(* 24 (- day (truncate day))))))
(list (list (car adj)
(format "%s %s"
(nth k (if s-hemi solar-s-hemi-seasons
solar-n-hemi-seasons))
(apply 'solar-time-string (cdr adj))))))))
(d (solar-date-next-longitude
(calendar-astro-from-absolute
(calendar-absolute-from-gregorian
(list (+ 3 (* k 3)) 15 y)))
90))
(abs-day (calendar-absolute-from-astro d)))
(list
(list (calendar-gregorian-from-absolute (floor abs-day))
(format "%s %s"
(nth k (if (and calendar-latitude
(< (calendar-latitude) 0))
solar-s-hemi-seasons
solar-n-hemi-seasons))
(solar-time-string
(* 24 (- abs-day (floor abs-day)))
(if (dst-in-effect abs-day)
calendar-daylight-time-zone-name
calendar-standard-time-zone-name))))))))
(provide 'solar)
......
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