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1097 lines
44 KiB
EmacsLisp
1097 lines
44 KiB
EmacsLisp
;;; solar.el --- calendar functions for solar events
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;; Copyright (C) 1992, 1993, 1995, 1997 Free Software Foundation, Inc.
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;; Author: Edward M. Reingold <reingold@cs.uiuc.edu>
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;; Denis B. Roegel <Denis.Roegel@loria.fr>
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;; Keywords: calendar
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;; Human-Keywords: sunrise, sunset, equinox, solstice, calendar, diary,
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;; holidays
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;; This file is part of GNU Emacs.
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;; GNU Emacs is free software; you can redistribute it and/or modify
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;; it under the terms of the GNU General Public License as published by
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;; the Free Software Foundation; either version 2, or (at your option)
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;; any later version.
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;; GNU Emacs is distributed in the hope that it will be useful,
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;; but WITHOUT ANY WARRANTY; without even the implied warranty of
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;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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;; GNU General Public License for more details.
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;; You should have received a copy of the GNU General Public License
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;; along with GNU Emacs; see the file COPYING. If not, write to the
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;; Free Software Foundation, Inc., 59 Temple Place - Suite 330,
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;; Boston, MA 02111-1307, USA.
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;;; Commentary:
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;; This collection of functions implements the features of calendar.el,
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;; diary.el, and holiday.el that deal with times of day, sunrise/sunset, and
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;; equinoxes/solstices.
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;; Based on the ``Almanac for Computers 1984,'' prepared by the Nautical
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;; Almanac Office, United States Naval Observatory, Washington, 1984, on
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;; ``Astronomical Formulae for Calculators,'' 3rd ed., by Jean Meeus,
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;; Willmann-Bell, Inc., 1985, on ``Astronomical Algorithms'' by Jean Meeus,
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;; Willmann-Bell, Inc., 1991, and on ``Planetary Programs and Tables from
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;; -4000 to +2800'' by Pierre Bretagnon and Jean-Louis Simon, Willmann-Bell,
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;; Inc., 1986.
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;;
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;; Accuracy:
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;; 1. Sunrise/sunset times will be accurate to the minute for years
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;; 1951--2050. For other years the times will be within +/- 2 minutes.
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;;
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;; 2. Equinox/solstice times will be accurate to the minute for years
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;; 1951--2050. For other years the times will be within +/- 1 minute.
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;; Technical details of all the calendrical calculations can be found in
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;; ``Calendrical Calculations'' by Nachum Dershowitz and Edward M. Reingold,
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;; Cambridge University Press (1997).
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;; Comments, corrections, and improvements should be sent to
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;; Edward M. Reingold Department of Computer Science
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;; (217) 333-6733 University of Illinois at Urbana-Champaign
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;; reingold@cs.uiuc.edu 1304 West Springfield Avenue
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;; Urbana, Illinois 61801
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;;; Code:
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(if (fboundp 'atan)
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(require 'lisp-float-type)
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(error "Solar/lunar calculations impossible since floating point is unavailable"))
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(require 'cal-dst)
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(require 'cal-julian)
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;;;###autoload
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(defcustom calendar-time-display-form
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'(12-hours ":" minutes am-pm
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(if time-zone " (") time-zone (if time-zone ")"))
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"*The pseudo-pattern that governs the way a time of day is formatted.
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A pseudo-pattern is a list of expressions that can involve the keywords
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`12-hours', `24-hours', and `minutes', all numbers in string form,
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and `am-pm' and `time-zone', both alphabetic strings.
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For example, the form
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'(24-hours \":\" minutes
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(if time-zone \" (\") time-zone (if time-zone \")\"))
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would give military-style times like `21:07 (UTC)'."
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:type 'sexp
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:group 'calendar)
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;;;###autoload
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(defcustom calendar-latitude nil
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"*Latitude of `calendar-location-name' in degrees.
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The value can be either a decimal fraction (one place of accuracy is
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sufficient), + north, - south, such as 40.7 for New York City, or the value
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can be a vector [degrees minutes north/south] such as [40 50 north] for New
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York City.
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This variable should be set in `site-start'.el."
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:type '(choice (const nil)
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(number :tag "Exact")
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(vector :value [0 0 north]
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(integer :tag "Degrees")
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(integer :tag "Minutes")
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(choice :tag "Position"
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(const north)
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(const south))))
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:group 'calendar)
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;;;###autoload
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(defcustom calendar-longitude nil
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"*Longitude of `calendar-location-name' in degrees.
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The value can be either a decimal fraction (one place of accuracy is
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sufficient), + east, - west, such as -73.9 for New York City, or the value
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can be a vector [degrees minutes east/west] such as [73 55 west] for New
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York City.
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This variable should be set in `site-start'.el."
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:type '(choice (const nil)
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(number :tag "Exact")
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(vector :value [0 0 west]
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(integer :tag "Degrees")
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(integer :tag "Minutes")
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(choice :tag "Position"
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(const east)
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(const west))))
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:group 'calendar)
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(defsubst calendar-latitude ()
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"Convert calendar-latitude to a signed decimal fraction, if needed."
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(if (numberp calendar-latitude)
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calendar-latitude
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(let ((lat (+ (aref calendar-latitude 0)
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(/ (aref calendar-latitude 1) 60.0))))
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(if (equal (aref calendar-latitude 2) 'north)
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lat
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(- lat)))))
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(defsubst calendar-longitude ()
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"Convert calendar-longitude to a signed decimal fraction, if needed."
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(if (numberp calendar-longitude)
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calendar-longitude
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(let ((long (+ (aref calendar-longitude 0)
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(/ (aref calendar-longitude 1) 60.0))))
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(if (equal (aref calendar-longitude 2) 'east)
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long
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(- long)))))
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;;;###autoload
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(defcustom calendar-location-name
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'(let ((float-output-format "%.1f"))
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(format "%s%s, %s%s"
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(if (numberp calendar-latitude)
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(abs calendar-latitude)
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(+ (aref calendar-latitude 0)
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(/ (aref calendar-latitude 1) 60.0)))
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(if (numberp calendar-latitude)
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(if (> calendar-latitude 0) "N" "S")
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(if (equal (aref calendar-latitude 2) 'north) "N" "S"))
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(if (numberp calendar-longitude)
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(abs calendar-longitude)
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(+ (aref calendar-longitude 0)
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(/ (aref calendar-longitude 1) 60.0)))
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(if (numberp calendar-longitude)
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(if (> calendar-longitude 0) "E" "W")
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(if (equal (aref calendar-longitude 2) 'east) "E" "W"))))
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"*Expression evaluating to name of `calendar-longitude', `calendar-latitude'.
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For example, \"New York City\". Default value is just the latitude, longitude
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pair.
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This variable should be set in `site-start'.el."
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:type 'sexp
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:group 'calendar)
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(defcustom solar-error 0.5
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"*Tolerance (in minutes) for sunrise/sunset calculations.
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A larger value makes the calculations for sunrise/sunset faster, but less
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accurate. The default is half a minute (30 seconds), so that sunrise/sunset
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times will be correct to the minute.
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It is useless to set the value smaller than 4*delta, where delta is the
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accuracy in the longitude of the sun (given by the function
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`solar-ecliptic-coordinates') in degrees since (delta/360) x (86400/60) = 4 x
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delta. At present, delta = 0.01 degrees, so the value of the variable
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`solar-error' should be at least 0.04 minutes (about 2.5 seconds)."
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:type 'number
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:group 'calendar)
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(defvar solar-n-hemi-seasons
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'("Vernal Equinox" "Summer Solstice" "Autumnal Equinox" "Winter Solstice")
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"List of season changes for the northern hemisphere.")
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(defvar solar-s-hemi-seasons
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'("Autumnal Equinox" "Winter Solstice" "Vernal Equinox" "Summer Solstice")
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"List of season changes for the southern hemisphere.")
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(defvar solar-sidereal-time-greenwich-midnight
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nil
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"Sidereal time at Greenwich at midnight (universal time).")
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(defvar solar-northern-spring-or-summer-season nil
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"Non-nil if northern spring or summer and nil otherwise.
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Needed for polar areas, in order to know whether the day lasts 0 or 24 hours.")
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(defun solar-setup ()
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"Prompt user for latitude, longitude, and time zone."
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(beep)
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(if (not calendar-longitude)
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(setq calendar-longitude
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(solar-get-number
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"Enter longitude (decimal fraction; + east, - west): ")))
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(if (not calendar-latitude)
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(setq calendar-latitude
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(solar-get-number
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"Enter latitude (decimal fraction; + north, - south): ")))
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(if (not calendar-time-zone)
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(setq calendar-time-zone
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(solar-get-number
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"Enter difference from Coordinated Universal Time (in minutes): "))))
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(defun solar-get-number (prompt)
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"Return a number from the minibuffer, prompting with PROMPT.
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Returns nil if nothing was entered."
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(let ((x (read-string prompt "")))
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(if (not (string-equal x ""))
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(string-to-int x))))
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;; The condition-case stuff is needed to catch bogus arithmetic
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;; exceptions that occur on some machines (like Sparcs)
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(defun solar-sin-degrees (x)
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(condition-case nil
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(sin (degrees-to-radians (mod x 360.0)))
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(solar-sin-degrees x)))
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(defun solar-cosine-degrees (x)
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(condition-case nil
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(cos (degrees-to-radians (mod x 360.0)))
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(solar-cosine-degrees x)))
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(defun solar-tangent-degrees (x)
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(condition-case nil
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(tan (degrees-to-radians (mod x 360.0)))
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(solar-tangent-degrees x)))
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(defun solar-xy-to-quadrant (x y)
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"Determines the quadrant of the point X, Y."
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(if (> x 0)
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(if (> y 0) 1 4)
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(if (> y 0) 2 3)))
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(defun solar-degrees-to-quadrant (angle)
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"Determines the quadrant of ANGLE."
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(1+ (floor (mod angle 360) 90)))
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(defun solar-arctan (x quad)
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"Arctangent of X in quadrant QUAD."
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(let ((deg (radians-to-degrees (atan x))))
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(cond ((equal quad 2) (+ deg 180))
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((equal quad 3) (+ deg 180))
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((equal quad 4) (+ deg 360))
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(t deg))))
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(defun solar-atn2 (x y)
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"Arctan of point X, Y."
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(if (= x 0)
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(if (> y 0) 90 270)
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(solar-arctan (/ y x) (solar-xy-to-quadrant x y))))
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(defun solar-arccos (x)
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"Arcos of X."
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(let ((y (sqrt (- 1 (* x x)))))
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(solar-atn2 x y)))
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(defun solar-arcsin (y)
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"Arcsin of Y."
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(let ((x (sqrt (- 1 (* y y)))))
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(solar-atn2 x y)
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))
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(defsubst solar-degrees-to-hours (degrees)
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"Convert DEGREES to hours."
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(/ degrees 15.0))
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(defsubst solar-hours-to-days (hour)
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"Convert HOUR to decimal fraction of a day."
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(/ hour 24.0))
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(defun solar-right-ascension (longitude obliquity)
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"Right ascension of the sun, in hours, given LONGITUDE and OBLIQUITY.
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Both arguments are in degrees."
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(solar-degrees-to-hours
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(solar-arctan
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(* (solar-cosine-degrees obliquity) (solar-tangent-degrees longitude))
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(solar-degrees-to-quadrant longitude))))
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(defun solar-declination (longitude obliquity)
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"Declination of the sun, in degrees, given LONGITUDE and OBLIQUITY.
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Both arguments are in degrees."
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(solar-arcsin
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(* (solar-sin-degrees obliquity)
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(solar-sin-degrees longitude))))
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(defun solar-sunrise-and-sunset (time latitude longitude height)
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"Sunrise, sunset and length of day.
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Parameters are the midday TIME and the LATITUDE, LONGITUDE of the location.
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TIME is a pair with the first component being the number of Julian centuries
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elapsed at 0 Universal Time, and the second component being the universal
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time. For instance, the pair corresponding to November 28, 1995 at 16 UT is
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\(-0.040945 16), -0.040945 being the number of julian centuries elapsed between
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Jan 1, 2000 at 12 UT and November 28, 1995 at 0 UT.
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HEIGHT is the angle the center of the sun has over the horizon for the contact
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we are trying to find. For sunrise and sunset, it is usually -0.61 degrees,
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accounting for the edge of the sun being on the horizon.
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Coordinates are included because this function is called with latitude=1
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degrees to find out if polar regions have 24 hours of sun or only night."
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(let* ((rise-time (solar-moment -1 latitude longitude time height))
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(set-time (solar-moment 1 latitude longitude time height))
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(day-length))
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(if (not (and rise-time set-time))
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(if (or (and (> latitude 0)
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solar-northern-spring-or-summer-season)
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(and (< latitude 0)
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(not solar-northern-spring-or-summer-season)))
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(setq day-length 24)
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(setq day-length 0))
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(setq day-length (- set-time rise-time)))
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(list (if rise-time (+ rise-time (/ calendar-time-zone 60.0)) nil)
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(if set-time (+ set-time (/ calendar-time-zone 60.0)) nil)
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day-length)))
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(defun solar-moment (direction latitude longitude time height)
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"Sunrise/sunset at location.
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Sunrise if DIRECTION =-1 or sunset if =1 at LATITUDE, LONGITUDE, with midday
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being TIME.
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TIME is a pair with the first component being the number of Julian centuries
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elapsed at 0 Universal Time, and the second component being the universal
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time. For instance, the pair corresponding to November 28, 1995 at 16 UT is
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\(-0.040945 16), -0.040945 being the number of julian centuries elapsed between
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Jan 1, 2000 at 12 UT and November 28, 1995 at 0 UT.
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HEIGHT is the angle the center of the sun has over the horizon for the contact
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we are trying to find. For sunrise and sunset, it is usually -0.61 degrees,
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accounting for the edge of the sun being on the horizon.
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Uses binary search."
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(let* ((ut (car (cdr time)))
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(possible t) ; we assume that rise or set are possible
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(utmin (+ ut (* direction 12.0)))
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(utmax ut) ; the time searched is between utmin and utmax
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; utmin and utmax are in hours
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(utmoment-old 0.0) ; rise or set approximation
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(utmoment 1.0) ; rise or set approximation
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(hut 0) ; sun height at utmoment
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(t0 (car time))
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(hmin (car (cdr
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(solar-horizontal-coordinates (list t0 utmin)
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latitude longitude t))))
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(hmax (car (cdr
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(solar-horizontal-coordinates (list t0 utmax)
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latitude longitude t)))))
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; -0.61 degrees is the height of the middle of the sun, when it rises
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; or sets.
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(if (< hmin height)
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(if (> hmax height)
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(while ;(< i 20) ; we perform a simple dichotomy
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; (> (abs (- hut height)) epsilon)
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(>= (abs (- utmoment utmoment-old))
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(/ solar-error 60))
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(setq utmoment-old utmoment)
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(setq utmoment (/ (+ utmin utmax) 2))
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(setq hut (car (cdr
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(solar-horizontal-coordinates
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(list t0 utmoment) latitude longitude t))))
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(if (< hut height) (setq utmin utmoment))
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(if (> hut height) (setq utmax utmoment))
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)
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(setq possible nil)) ; the sun never rises
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(setq possible nil)) ; the sun never sets
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(if (not possible) nil utmoment)))
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(defun solar-time-string (time time-zone)
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"Printable form for decimal fraction TIME in TIME-ZONE.
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Format used is given by `calendar-time-display-form'."
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(let* ((time (round (* 60 time)))
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(24-hours (/ time 60))
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(minutes (format "%02d" (% time 60)))
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(12-hours (format "%d" (1+ (% (+ 24-hours 11) 12))))
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(am-pm (if (>= 24-hours 12) "pm" "am"))
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(24-hours (format "%02d" 24-hours)))
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(mapconcat 'eval calendar-time-display-form "")))
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(defun solar-daylight (time)
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"Printable form for time expressed in hours."
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(format "%d:%02d"
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(floor time)
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(floor (* 60 (- time (floor time))))))
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(defun solar-exact-local-noon (date)
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"Date and Universal Time of local noon at *local date* date.
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The date may be different from the one asked for, but it will be the right
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local date. The second component of date should be an integer."
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(let* ((nd date)
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(ut (- 12.0 (/ (calendar-longitude) 15)))
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(te (solar-time-equation date ut)))
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(setq ut (- ut te))
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(if (>= ut 24)
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(progn
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(setq nd (list (car date) (+ 1 (car (cdr date)))
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(car (cdr (cdr date)))))
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(setq ut (- ut 24))))
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(if (< ut 0)
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(progn
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(setq nd (list (car date) (- (car (cdr date)) 1)
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(car (cdr (cdr date)))))
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(setq ut (+ ut 24))))
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(setq nd (calendar-gregorian-from-absolute
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(calendar-absolute-from-gregorian nd)))
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; date standardization
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(list nd ut)))
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(defun solar-sunrise-sunset (date)
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"List of *local* times of sunrise, sunset, and daylight on Gregorian DATE.
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Corresponding value is nil if there is no sunrise/sunset."
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(let* (; first, get the exact moment of local noon.
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(exact-local-noon (solar-exact-local-noon date))
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; get the time from the 2000 epoch.
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(t0 (solar-julian-ut-centuries (car exact-local-noon)))
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; store the sidereal time at Greenwich at midnight of UT time.
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; find if summer or winter slightly above the equator
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(equator-rise-set
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(progn (setq solar-sidereal-time-greenwich-midnight
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(solar-sidereal-time t0))
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(solar-sunrise-and-sunset
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(list t0 (car (cdr exact-local-noon)))
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1.0
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(calendar-longitude) 0)))
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; store the spring/summer information,
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; compute sunrise and sunset (two first components of rise-set).
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; length of day is the third component (it is only the difference
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; between sunset and sunrise when there is a sunset and a sunrise)
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(rise-set
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(progn
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(setq solar-northern-spring-or-summer-season
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(if (> (car (cdr (cdr equator-rise-set))) 12) t nil))
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(solar-sunrise-and-sunset
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(list t0 (car (cdr exact-local-noon)))
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(calendar-latitude)
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(calendar-longitude) -0.61)))
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(rise (car rise-set))
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(adj-rise (if rise (dst-adjust-time date rise) nil))
|
|
(set (car (cdr rise-set)))
|
|
(adj-set (if set (dst-adjust-time date set) nil))
|
|
(length (car (cdr (cdr rise-set)))) )
|
|
(list
|
|
(and rise (calendar-date-equal date (car adj-rise)) (cdr adj-rise))
|
|
(and set (calendar-date-equal date (car adj-set)) (cdr adj-set))
|
|
(solar-daylight length))))
|
|
|
|
(defun solar-sunrise-sunset-string (date)
|
|
"String of *local* times of sunrise, sunset, and daylight on Gregorian DATE."
|
|
(let ((l (solar-sunrise-sunset date)))
|
|
(format
|
|
"%s, %s at %s (%s hours daylight)"
|
|
(if (car l)
|
|
(concat "Sunrise " (apply 'solar-time-string (car l)))
|
|
"No sunrise")
|
|
(if (car (cdr l))
|
|
(concat "sunset " (apply 'solar-time-string (car (cdr l))))
|
|
"no sunset")
|
|
(eval calendar-location-name)
|
|
(car (cdr (cdr l))))))
|
|
|
|
(defun solar-julian-ut-centuries (date)
|
|
"Number of Julian centuries elapsed since 1 Jan, 2000 at noon U.T. for Gregorian DATE."
|
|
(/ (- (calendar-absolute-from-gregorian date)
|
|
(calendar-absolute-from-gregorian '(1 1.5 2000)))
|
|
36525.0))
|
|
|
|
(defun solar-ephemeris-time(time)
|
|
"Ephemeris Time at moment TIME.
|
|
|
|
TIME is a pair with the first component being the number of Julian centuries
|
|
elapsed at 0 Universal Time, and the second component being the universal
|
|
time. For instance, the pair corresponding to November 28, 1995 at 16 UT is
|
|
\(-0.040945 16), -0.040945 being the number of julian centuries elapsed between
|
|
Jan 1, 2000 at 12 UT and November 28, 1995 at 0 UT.
|
|
|
|
Result is in julian centuries of ephemeris time."
|
|
(let* ((t0 (car time))
|
|
(ut (car (cdr time)))
|
|
(t1 (+ t0 (/ (/ ut 24.0) 36525)))
|
|
(y (+ 2000 (* 100 t1)))
|
|
(dt (* 86400 (solar-ephemeris-correction (floor y)))))
|
|
(+ t1 (/ (/ dt 86400) 36525))))
|
|
|
|
(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-horizontal-coordinates
|
|
(time latitude longitude for-sunrise-sunset)
|
|
"Azimuth and height of the sun at TIME, LATITUDE, and LONGITUDE.
|
|
|
|
TIME is a pair with the first component being the number of Julian centuries
|
|
elapsed at 0 Universal Time, and the second component being the universal
|
|
time. For instance, the pair corresponding to November 28, 1995 at 16 UT is
|
|
\(-0.040945 16), -0.040945 being the number of julian centuries elapsed between
|
|
Jan 1, 2000 at 12 UT and November 28, 1995 at 0 UT.
|
|
|
|
The azimuth is given in degrees as well as the height (between -180 and 180)."
|
|
(let* ((ut (car (cdr time)))
|
|
(ec (solar-equatorial-coordinates time for-sunrise-sunset))
|
|
(st (+ solar-sidereal-time-greenwich-midnight
|
|
(* ut 1.00273790935)))
|
|
(ah (- (* st 15) (* 15 (car ec)) (* -1 (calendar-longitude))))
|
|
; hour angle (in degrees)
|
|
(de (car (cdr ec)))
|
|
(azimuth (solar-atn2 (- (* (solar-cosine-degrees ah)
|
|
(solar-sin-degrees latitude))
|
|
(* (solar-tangent-degrees de)
|
|
(solar-cosine-degrees latitude)))
|
|
(solar-sin-degrees ah)))
|
|
(height (solar-arcsin
|
|
(+ (* (solar-sin-degrees latitude) (solar-sin-degrees de))
|
|
(* (solar-cosine-degrees latitude)
|
|
(solar-cosine-degrees de)
|
|
(solar-cosine-degrees ah))))))
|
|
(if (> height 180) (setq height (- height 360)))
|
|
(list azimuth height)))
|
|
|
|
(defun solar-equatorial-coordinates (time for-sunrise-sunset)
|
|
"Right ascension (in hours) and declination (in degrees) of the sun at TIME.
|
|
|
|
TIME is a pair with the first component being the number of Julian centuries
|
|
elapsed at 0 Universal Time, and the second component being the universal
|
|
time. For instance, the pair corresponding to November 28, 1995 at 16 UT is
|
|
\(-0.040945 16), -0.040945 being the number of julian centuries elapsed between
|
|
Jan 1, 2000 at 12 UT and November 28, 1995 at 0 UT."
|
|
(let* ((tm (solar-ephemeris-time time))
|
|
(ec (solar-ecliptic-coordinates tm for-sunrise-sunset)))
|
|
(list (solar-right-ascension (car ec) (car (cdr ec)))
|
|
(solar-declination (car ec) (car (cdr ec))))))
|
|
|
|
(defun solar-ecliptic-coordinates (time for-sunrise-sunset)
|
|
"Apparent longitude of the sun, ecliptic inclination, (both in degrees)
|
|
equation of time (in hours) and nutation in longitude (in seconds)
|
|
at moment `time', expressed in julian centuries of Ephemeris Time
|
|
since January 1st, 2000, at 12 ET."
|
|
(let* ((l (+ 280.46645
|
|
(* 36000.76983 time)
|
|
(* 0.0003032 time time))) ; sun mean longitude
|
|
(ml (+ 218.3165
|
|
(* 481267.8813 time))) ; moon mean longitude
|
|
(m (+ 357.52910
|
|
(* 35999.05030 time)
|
|
(* -0.0001559 time time)
|
|
(* -0.00000048 time time time))) ; sun mean anomaly
|
|
(i (+ 23.43929111 (* -0.013004167 time)
|
|
(* -0.00000016389 time time)
|
|
(* 0.0000005036 time time time))); mean inclination
|
|
(c (+ (* (+ 1.914600
|
|
(* -0.004817 time)
|
|
(* -0.000014 time time))
|
|
(solar-sin-degrees m))
|
|
(* (+ 0.019993 (* -0.000101 time))
|
|
(solar-sin-degrees (* 2 m)))
|
|
(* 0.000290
|
|
(solar-sin-degrees (* 3 m))))) ; center equation
|
|
(L (+ l c)) ; total longitude
|
|
(omega (+ 125.04
|
|
(* -1934.136 time))) ; longitude of moon's ascending node
|
|
; on the ecliptic
|
|
(nut (if (not for-sunrise-sunset)
|
|
(+ (* -17.20 (solar-sin-degrees omega))
|
|
(* -1.32 (solar-sin-degrees (* 2 l)))
|
|
(* -0.23 (solar-sin-degrees (* 2 ml)))
|
|
(* 0.21 (solar-sin-degrees (* 2 omega))))
|
|
nil))
|
|
; nut = nutation in longitude, measured in seconds of angle.
|
|
(ecc (if (not for-sunrise-sunset)
|
|
(+ 0.016708617
|
|
(* -0.000042037 time)
|
|
(* -0.0000001236 time time)) ; eccentricity of earth's orbit
|
|
nil))
|
|
(app (+ L
|
|
-0.00569
|
|
(* -0.00478
|
|
(solar-sin-degrees omega)))) ; apparent longitude of sun
|
|
(y (if (not for-sunrise-sunset)
|
|
(* (solar-tangent-degrees (/ i 2))
|
|
(solar-tangent-degrees (/ i 2)))
|
|
nil))
|
|
(time-eq (if (not for-sunrise-sunset)
|
|
(/ (* 12 (+ (* y (solar-sin-degrees (* 2 l)))
|
|
(* -2 ecc (solar-sin-degrees m))
|
|
(* 4 ecc y (solar-sin-degrees m)
|
|
(solar-cosine-degrees (* 2 l)))
|
|
(* -0.5 y y (solar-sin-degrees (* 4 l)))
|
|
(* -1.25 ecc ecc (solar-sin-degrees (* 2 m)))))
|
|
3.1415926535)
|
|
nil)))
|
|
; equation of time, in hours
|
|
(list app i time-eq nut)))
|
|
|
|
(defun solar-longitude (d)
|
|
"Longitude of sun on astronomical (Julian) day number D.
|
|
Accurary is about 0.0006 degree (about 365.25*24*60*0.0006/360 = 1 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))
|
|
;; get Universal Time
|
|
(date (calendar-astro-from-absolute
|
|
(- a-d
|
|
(if (dst-in-effect a-d)
|
|
(/ calendar-daylight-time-offset 24.0 60.0) 0)
|
|
(/ calendar-time-zone 60.0 24.0))))
|
|
;; get Ephemeris Time
|
|
(date (+ date (solar-ephemeris-correction
|
|
(extract-calendar-year
|
|
(calendar-gregorian-from-absolute
|
|
(floor
|
|
(calendar-absolute-from-astro
|
|
date)))))))
|
|
(U (/ (- date 2451545) 3652500))
|
|
(longitude
|
|
(+ 4.9353929
|
|
(* 62833.1961680 U)
|
|
(* 0.0000001
|
|
(apply '+
|
|
(mapcar '(lambda (x)
|
|
(* (car x)
|
|
(sin (mod
|
|
(+ (car (cdr x))
|
|
(* (car (cdr (cdr x))) U))
|
|
(* 2 pi)))))
|
|
solar-data-list)))))
|
|
(aberration
|
|
(* 0.0000001 (- (* 17 (cos (+ 3.10 (* 62830.14 U)))) 973)))
|
|
(A1 (mod (+ 2.18 (* U (+ -3375.70 (* 0.36 U)))) (* 2 pi)))
|
|
(A2 (mod (+ 3.51 (* U (+ 125666.39 (* 0.10 U)))) (* 2 pi)))
|
|
(nutation (* -0.0000001 (+ (* 834 (sin A1)) (* 64 (sin A2))))))
|
|
(mod (radians-to-degrees (+ longitude aberration nutation)) 360.0)))
|
|
|
|
(defconst solar-data-list
|
|
'((403406 4.721964 1.621043)
|
|
(195207 5.937458 62830.348067)
|
|
(119433 1.115589 62830.821524)
|
|
(112392 5.781616 62829.634302)
|
|
(3891 5.5474 125660.5691)
|
|
(2819 1.5120 125660.984)
|
|
(1721 4.1897 62832.4766)
|
|
(0 1.163 0.813)
|
|
(660 5.415 125659.31)
|
|
(350 4.315 57533.85)
|
|
(334 4.553 -33.931)
|
|
(314 5.198 777137.715)
|
|
(268 5.989 78604.191)
|
|
(242 2.911 5.412)
|
|
(234 1.423 39302.098)
|
|
(158 0.061 -34.861)
|
|
(132 2.317 115067.698)
|
|
(129 3.193 15774.337)
|
|
(114 2.828 5296.670)
|
|
(99 0.52 58849.27)
|
|
(93 4.65 5296.11)
|
|
(86 4.35 -3980.70)
|
|
(78 2.75 52237.69)
|
|
(72 4.50 55076.47)
|
|
(68 3.23 261.08)
|
|
(64 1.22 15773.85)
|
|
(46 0.14 188491.03)
|
|
(38 3.44 -7756.55)
|
|
(37 4.37 264.89)
|
|
(32 1.14 117906.27)
|
|
(29 2.84 55075.75)
|
|
(28 5.96 -7961.39)
|
|
(27 5.09 188489.81)
|
|
(27 1.72 2132.19)
|
|
(25 2.56 109771.03)
|
|
(24 1.92 54868.56)
|
|
(21 0.09 25443.93)
|
|
(21 5.98 -55731.43)
|
|
(20 4.03 60697.74)
|
|
(18 4.47 2132.79)
|
|
(17 0.79 109771.63)
|
|
(14 4.24 -7752.82)
|
|
(13 2.01 188491.91)
|
|
(13 2.65 207.81)
|
|
(13 4.98 29424.63)
|
|
(12 0.93 -7.99)
|
|
(10 2.21 46941.14)
|
|
(10 3.59 -68.29)
|
|
(10 1.50 21463.25)
|
|
(10 2.55 157208.40)))
|
|
|
|
(defun solar-ephemeris-correction (year)
|
|
"Ephemeris time minus Universal Time during Gregorian year.
|
|
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)))))
|
|
|
|
(defun solar-sidereal-time (t0)
|
|
"Sidereal time (in hours) in Greenwich.
|
|
|
|
At T0=Julian centuries of universal time.
|
|
T0 must correspond to 0 hours UT."
|
|
(let* ((mean-sid-time (+ 6.6973746
|
|
(* 2400.051337 t0)
|
|
(* 0.0000258622 t0 t0)
|
|
(* -0.0000000017222 t0 t0 t0)))
|
|
(et (solar-ephemeris-time (list t0 0.0)))
|
|
(nut-i (solar-ecliptic-coordinates et nil))
|
|
(nut (car (cdr (cdr (cdr nut-i))))) ; nutation
|
|
(i (car (cdr nut-i)))) ; inclination
|
|
(mod (+ (mod (+ mean-sid-time
|
|
(/ (/ (* nut (solar-cosine-degrees i)) 15) 3600)) 24.0)
|
|
24.0)
|
|
24.0)))
|
|
|
|
(defun solar-time-equation (date ut)
|
|
"Equation of time expressed in hours at Gregorian DATE at Universal time UT."
|
|
(let* ((et (solar-date-to-et date ut))
|
|
(ec (solar-ecliptic-coordinates et nil)))
|
|
(car (cdr (cdr ec)))))
|
|
|
|
(defun solar-date-to-et (date ut)
|
|
"Ephemeris Time at Gregorian DATE at Universal Time UT (in hours).
|
|
Expressed in julian centuries of Ephemeris Time."
|
|
(let ((t0 (solar-julian-ut-centuries date)))
|
|
(solar-ephemeris-time (list t0 ut))))
|
|
|
|
;;;###autoload
|
|
(defun sunrise-sunset (&optional arg)
|
|
"Local time of sunrise and sunset for today. Accurate to a few seconds.
|
|
If called with an optional prefix argument, prompt for date.
|
|
|
|
If called with an optional double prefix argument, prompt for longitude,
|
|
latitude, time zone, and date, and always use standard time.
|
|
|
|
This function is suitable for execution in a .emacs file."
|
|
(interactive "p")
|
|
(or arg (setq arg 1))
|
|
(if (and (< arg 16)
|
|
(not (and calendar-latitude calendar-longitude calendar-time-zone)))
|
|
(solar-setup))
|
|
(let* ((calendar-longitude
|
|
(if (< arg 16) calendar-longitude
|
|
(solar-get-number
|
|
"Enter longitude (decimal fraction; + east, - west): ")))
|
|
(calendar-latitude
|
|
(if (< arg 16) calendar-latitude
|
|
(solar-get-number
|
|
"Enter latitude (decimal fraction; + north, - south): ")))
|
|
(calendar-time-zone
|
|
(if (< arg 16) calendar-time-zone
|
|
(solar-get-number
|
|
"Enter difference from Coordinated Universal Time (in minutes): ")))
|
|
(calendar-location-name
|
|
(if (< arg 16) calendar-location-name
|
|
(let ((float-output-format "%.1f"))
|
|
(format "%s%s, %s%s"
|
|
(if (numberp calendar-latitude)
|
|
(abs calendar-latitude)
|
|
(+ (aref calendar-latitude 0)
|
|
(/ (aref calendar-latitude 1) 60.0)))
|
|
(if (numberp calendar-latitude)
|
|
(if (> calendar-latitude 0) "N" "S")
|
|
(if (equal (aref calendar-latitude 2) 'north) "N" "S"))
|
|
(if (numberp calendar-longitude)
|
|
(abs calendar-longitude)
|
|
(+ (aref calendar-longitude 0)
|
|
(/ (aref calendar-longitude 1) 60.0)))
|
|
(if (numberp calendar-longitude)
|
|
(if (> calendar-longitude 0) "E" "W")
|
|
(if (equal (aref calendar-longitude 2) 'east)
|
|
"E" "W"))))))
|
|
(calendar-standard-time-zone-name
|
|
(if (< arg 16) calendar-standard-time-zone-name
|
|
(cond ((= calendar-time-zone 0) "UTC")
|
|
((< calendar-time-zone 0)
|
|
(format "UTC%dmin" calendar-time-zone))
|
|
(t (format "UTC+%dmin" calendar-time-zone)))))
|
|
(calendar-daylight-savings-starts
|
|
(if (< arg 16) calendar-daylight-savings-starts))
|
|
(calendar-daylight-savings-ends
|
|
(if (< arg 16) calendar-daylight-savings-ends))
|
|
(date (if (< arg 4) (calendar-current-date) (calendar-read-date)))
|
|
(date-string (calendar-date-string date t))
|
|
(time-string (solar-sunrise-sunset-string date))
|
|
(msg (format "%s: %s" date-string time-string))
|
|
(one-window (one-window-p t)))
|
|
(if (<= (length msg) (frame-width))
|
|
(message "%s" msg)
|
|
(with-output-to-temp-buffer "*temp*"
|
|
(princ (concat date-string "\n" time-string)))
|
|
(message "%s"
|
|
(substitute-command-keys
|
|
(if one-window
|
|
(if pop-up-windows
|
|
"Type \\[delete-other-windows] to remove temp window."
|
|
"Type \\[switch-to-buffer] RET to remove temp window.")
|
|
"Type \\[switch-to-buffer-other-window] RET to restore old contents of temp window."))))))
|
|
|
|
(defun calendar-sunrise-sunset ()
|
|
"Local time of sunrise and sunset for date under cursor.
|
|
Accurate to a few seconds."
|
|
(interactive)
|
|
(if (not (and calendar-latitude calendar-longitude calendar-time-zone))
|
|
(solar-setup))
|
|
(let ((date (calendar-cursor-to-date t)))
|
|
(message "%s: %s"
|
|
(calendar-date-string date t t)
|
|
(solar-sunrise-sunset-string date))))
|
|
|
|
(defun diary-sunrise-sunset ()
|
|
"Local time of sunrise and sunset as a diary entry.
|
|
Accurate to a few seconds."
|
|
(if (not (and calendar-latitude calendar-longitude calendar-time-zone))
|
|
(solar-setup))
|
|
(solar-sunrise-sunset-string date))
|
|
|
|
(defcustom diary-sabbath-candles-minutes 18
|
|
"*Number of minutes before sunset for sabbath candle lighting."
|
|
:group 'diary
|
|
:type 'integer
|
|
:version "21.1")
|
|
|
|
(defun diary-sabbath-candles (&optional mark)
|
|
"Local time of candle lighting diary entry--applies if date is a Friday.
|
|
No diary entry if there is no sunset on that date.
|
|
|
|
An optional parameter MARK specifies a face or single-character string to
|
|
use when highlighting the day in the calendar."
|
|
(if (not (and calendar-latitude calendar-longitude calendar-time-zone))
|
|
(solar-setup))
|
|
(if (= (% (calendar-absolute-from-gregorian date) 7) 5);; Friday
|
|
(let* ((sunset (car (cdr (solar-sunrise-sunset date))))
|
|
(light (if sunset
|
|
(cons (- (car sunset)
|
|
(/ diary-sabbath-candles-minutes 60.0))
|
|
(cdr sunset)))))
|
|
(if sunset
|
|
(cons mark
|
|
(format "%s Sabbath candle lighting"
|
|
(apply 'solar-time-string light)))))))
|
|
|
|
(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.
|
|
RESULT is a gregorian local date.
|
|
|
|
Accurate to less than a minute between 1951 and 2050."
|
|
(let* ((JDE0 (solar-mean-equinoxes/solstices k year))
|
|
(T (/ (- JDE0 2451545.0) 36525))
|
|
(W (- (* 35999.373 T) 2.47))
|
|
(Delta-lambda (+ 1 (* 0.0334 (solar-cosine-degrees W))
|
|
(* 0.0007 (solar-cosine-degrees (* 2 W)))))
|
|
(S (apply '+ (mapcar '(lambda(x)
|
|
(* (car x) (solar-cosine-degrees
|
|
(+ (* (car (cdr (cdr x))) T)
|
|
(car (cdr x))))))
|
|
solar-seasons-data)))
|
|
(JDE (+ JDE0 (/ (* 0.00001 S) Delta-lambda)))
|
|
(correction (+ 102.3 (* 123.5 T) (* 32.5 T T)))
|
|
; ephemeris time correction
|
|
(JD (- JDE (/ correction 86400)))
|
|
(date (calendar-gregorian-from-absolute (floor (- JD 1721424.5))))
|
|
(time (- (- JD 0.5) (floor (- JD 0.5))))
|
|
)
|
|
(list (car date) (+ (car (cdr date)) time
|
|
(/ (/ calendar-time-zone 60.0) 24.0))
|
|
(car (cdr (cdr date))))))
|
|
|
|
; from Meeus, 1991, page 166
|
|
(defun solar-mean-equinoxes/solstices (k year)
|
|
"Julian day of mean equinox/solstice K for YEAR.
|
|
K=0, spring equinox; K=1, summer solstice; K=2, fall equinox; K=3, winter
|
|
solstice. These formulas are only to be used between 1000 BC and 3000 AD."
|
|
(let ((y (/ year 1000.0))
|
|
(z (/ (- year 2000) 1000.0)))
|
|
(if (< year 1000) ; actually between -1000 and 1000
|
|
(cond ((equal k 0) (+ 1721139.29189
|
|
(* 365242.13740 y)
|
|
(* 0.06134 y y)
|
|
(* 0.00111 y y y)
|
|
(* -0.00071 y y y y)))
|
|
((equal k 1) (+ 1721233.25401
|
|
(* 365241.72562 y)
|
|
(* -0.05323 y y)
|
|
(* 0.00907 y y y)
|
|
(* 0.00025 y y y y)))
|
|
((equal k 2) (+ 1721325.70455
|
|
(* 365242.49558 y)
|
|
(* -0.11677 y y)
|
|
(* -0.00297 y y y)
|
|
(* 0.00074 y y y y)))
|
|
((equal k 3) (+ 1721414.39987
|
|
(* 365242.88257 y)
|
|
(* -0.00769 y y)
|
|
(* -0.00933 y y y)
|
|
(* -0.00006 y y y y))))
|
|
; actually between 1000 and 3000
|
|
(cond ((equal k 0) (+ 2451623.80984
|
|
(* 365242.37404 z)
|
|
(* 0.05169 z z)
|
|
(* -0.00411 z z z)
|
|
(* -0.00057 z z z z)))
|
|
((equal k 1) (+ 2451716.56767
|
|
(* 365241.62603 z)
|
|
(* 0.00325 z z)
|
|
(* 0.00888 z z z)
|
|
(* -0.00030 z z z z)))
|
|
((equal k 2) (+ 2451810.21715
|
|
(* 365242.01767 z)
|
|
(* -0.11575 z z)
|
|
(* 0.00337 z z z)
|
|
(* 0.00078 z z z z)))
|
|
((equal k 3) (+ 2451900.05952
|
|
(* 365242.74049 z)
|
|
(* -0.06223 z z)
|
|
(* -0.00823 z z z)
|
|
(* 0.00032 z z z z)))))))
|
|
|
|
; from Meeus, 1991, page 167
|
|
(defconst solar-seasons-data
|
|
'((485 324.96 1934.136)
|
|
(203 337.23 32964.467)
|
|
(199 342.08 20.186)
|
|
(182 27.85 445267.112)
|
|
(156 73.14 45036.886)
|
|
(136 171.52 22518.443)
|
|
(77 222.54 65928.934)
|
|
(74 296.72 3034.906)
|
|
(70 243.58 9037.513)
|
|
(58 119.81 33718.147)
|
|
(52 297.17 150.678)
|
|
(50 21.02 2281.226)
|
|
(45 247.54 29929.562)
|
|
(44 325.15 31555.956)
|
|
(29 60.93 4443.417)
|
|
(18 155.12 67555.328)
|
|
(17 288.79 4562.452)
|
|
(16 198.04 62894.029)
|
|
(14 199.76 31436.921)
|
|
(12 95.39 14577.848)
|
|
(12 287.11 31931.756)
|
|
(12 320.81 34777.259)
|
|
(9 227.73 1222.114)
|
|
(8 15.45 16859.074)))
|
|
|
|
;;;###autoload
|
|
(defun solar-equinoxes-solstices ()
|
|
"*local* date and time of equinoxes and solstices, if visible in the calendar window.
|
|
Requires floating point."
|
|
(let ((m displayed-month)
|
|
(y displayed-year))
|
|
(increment-calendar-month m y (cond ((= 1 (% m 3)) -1)
|
|
((= 2 (% m 3)) 1)
|
|
(t 0)))
|
|
(let* ((calendar-standard-time-zone-name
|
|
(if calendar-time-zone calendar-standard-time-zone-name "UTC"))
|
|
(calendar-daylight-savings-starts
|
|
(if calendar-time-zone calendar-daylight-savings-starts))
|
|
(calendar-daylight-savings-ends
|
|
(if calendar-time-zone calendar-daylight-savings-ends))
|
|
(calendar-time-zone (if calendar-time-zone calendar-time-zone 0))
|
|
(k (1- (/ m 3)))
|
|
(d0 (solar-equinoxes/solstices k y))
|
|
(d1 (list (car d0) (floor (car (cdr d0))) (car (cdr (cdr d0)))))
|
|
(h0 (* 24 (- (car (cdr d0)) (floor (car (cdr d0))))))
|
|
(adj (dst-adjust-time d1 h0))
|
|
(d (list (car (car adj))
|
|
(+ (car (cdr (car adj)) )
|
|
(/ (car (cdr adj)) 24.0))
|
|
(car (cdr (cdr (car adj))))))
|
|
; The following is nearly as accurate, but not quite:
|
|
;(d0 (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)))
|
|
(abs-day (calendar-absolute-from-gregorian 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)
|
|
|
|
;;; solar.el ends here
|