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Update Bahá'í calendar for 2014 calendar reform
In 2014, the Universal House of Justice announced modifications to the Badí' calendar to bring it more in line with its original design. >From 172 BE (Naw-Rúz 2015) onwards, Naw-Rúz is determined by the vernal equinox as observed from Tehran, and the Twin Holy Birthdays are calculated from the eighth new moon after Naw-Rúz. * doc/emacs/calendar.texi (Calendar Systems): Update Bahá'í calendar description to mention the 2014 reform, Ayyám-i-Há, and the astronomical basis for Naw-Rúz and Twin Holy Birthday calculations. * lisp/calendar/cal-bahai.el: Require 'solar' and 'lunar' for astronomical calculations. (calendar-bahai-tehran-latitude) (calendar-bahai-tehran-longitude) (calendar-bahai-tehran-timezone) (calendar-bahai-reform-year): New constants for Tehran-based astronomical observations and reform year (172 BE). (calendar-bahai-nawruz-for-gregorian-year): New function to calculate Naw-Rúz from vernal equinox relative to Tehran sunset. (calendar-bahai-nawruz): New function returning absolute date of Naw-Rúz for a given Bahá'í year. (calendar-bahai-twin-holy-birthdays-for-year): New function to calculate Birth of the Báb and Birth of Bahá'u'lláh from the eighth new moon after Naw-Rúz. (calendar-bahai-leap-year-p): Handle post-reform years based on gap between successive Naw-Rúz dates. (calendar-bahai-to-absolute, calendar-bahai-from-absolute): Rewrite to use astronomical Naw-Rúz dates for years >= 172 BE. (holiday-bahai-new-year): Calculate variable Naw-Rúz date. (holiday-bahai-twin-holy-birthdays): New function for lunar-based Twin Holy Birthday dates. (holiday-bahai-ridvan): Use Bahá'í calendar dates instead of fixed Gregorian dates. (calendar-bahai--nawruz-reference-dates) (calendar-bahai--twin-birthdays-reference-dates): New constants with official dates from Bahá'í World Centre for 2015-2064. (calendar-bahai--verify-nawruz) (calendar-bahai--verify-twin-birthdays) (calendar-bahai-verify-calculations): New verification functions to test calculations against official reference data. * lisp/calendar/holidays.el (holiday-bahai-holidays): Use 'holiday-bahai' with Bahá'í calendar dates instead of 'holiday-fixed' with Gregorian dates. Add 'holiday-bahai-twin-holy-birthdays' for lunar-calculated dates.
This commit is contained in:
John Wiegley
Eli Zaretskii
parent
3d21eaa3fc
commit
1dd0fd6e4e
3 changed files with 527 additions and 52 deletions
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@ -826,9 +826,15 @@ twelve @dfn{terrestrial branches} for a total of sixty names that are
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repeated in a cycle of sixty.
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@cindex Bah@'a'@'i calendar
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The Bah@'a'@'i calendar system is based on a solar cycle of 19 months with
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19 days each. The four remaining intercalary days are placed
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between the 18th and 19th months.
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The Bah@'a'@'i calendar system is based on a solar cycle of 19 months
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with 19 days each. The remaining intercalary days (known as
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Ayy@'am-i-H@'a) are placed between the 18th and 19th months. Following
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a 2014 calendar reform by the Universal House of Justice, the date of
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Naw-R@'uz (New Year) is now determined by the vernal equinox as
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observed from Tehran, and the dates of the Twin Holy Birthdays (Birth
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of the B@'ab and Birth of Bah@'a'u'll@'ah) are calculated from the
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eighth new moon after Naw-R@'uz. For dates before 172 BE (2015 CE),
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the calendar follows the pre-reform fixed calculations.
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@node To Other Calendar
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@subsection Converting To Other Calendars
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@ -28,12 +28,11 @@
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;; and diary-lib.el that deal with the Bahá’í calendar.
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;; The Bahá’í (https://www.bahai.org) calendar system is based on a
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;; solar cycle of 19 months with 19 days each. The four remaining
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;; solar cycle of 19 months with 19 days each. The remaining
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;; "intercalary" days are called the Ayyám-i-Há (days of Há), and are
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;; placed between the 18th and 19th months. They are meant as a time
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;; of festivals preceding the 19th month, which is the month of
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;; fasting. In Gregorian leap years, there are 5 of these days (Há
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;; has the numerical value of 5 in the arabic abjad, or
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;; fasting. (Há has the numerical value of 5 in the arabic abjad, or
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;; letter-to-number, reckoning).
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;; Each month is named after an attribute of God, as are the 19 days
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@ -47,6 +46,23 @@
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;; each of which has its own name, again patterned after the
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;; attributes of God.
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;; CALENDAR REFORM (2014/172 BE):
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;; Prior to 172 BE (before Naw-Rúz 2015 CE), Naw-Rúz was fixed at
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;; March 21 and leap years followed the Gregorian pattern.
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;;
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;; From 172 BE onwards, the Universal House of Justice implemented
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;; astronomical observations:
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;; - Naw-Rúz is determined by the vernal equinox as observed from Tehran
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;; - Naw-Rúz can fall on March 19, 20, 21, or 22
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;; - Ayyám-i-Há has 4 or 5 days depending on the gap between successive
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;; Naw-Rúz dates (ensuring month 19 always ends the day before Naw-Rúz)
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;; - Days run from sunset to sunset; if the equinox occurs before sunset
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;; in Tehran, that day is Naw-Rúz; otherwise the next day is Naw-Rúz
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;;
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;; The implementation uses official tables from the Nautical Almanac
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;; Office for years 172-221 BE (2015-2064 CE), and astronomical
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;; calculations for years beyond this range.
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;; Note: The days of Ayyám-i-Há are encoded as zero and negative
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;; offsets from the first day of the final month. So, (19 -3 157) is
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;; the first day of Ayyám-i-Há, in the year 157 BE.
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@ -54,19 +70,161 @@
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;;; Code:
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(require 'calendar)
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(require 'solar)
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(require 'lunar)
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(defconst calendar-bahai-month-name-array
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["Bahá" "Jalál" "Jamál" "‘Aẓamat" "Núr" "Raḥmat" "Kalimát" "Kamál"
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"Asmá’" "‘Izzat" "Mas͟híyyat" "‘Ilm" "Qudrat" "Qawl" "Masá’il"
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"S͟haraf" "Sulṭán" "Mulk" "‘Alá’"]
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"Asmá’" "‘Izzat" "Mashíyyat" "‘Ilm" "Qudrat" "Qawl" "Masá’il"
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"Sharaf" "Sulṭán" "Mulk" "‘Alá’"]
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"Array of the month names in the Bahá’í calendar.")
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(defconst calendar-bahai-epoch (calendar-absolute-from-gregorian '(3 21 1844))
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"Absolute date of start of Bahá’í calendar = March 21, 1844 AD.")
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;; Constants for Tehran, Iran (observing location for equinox)
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(defconst calendar-bahai-tehran-latitude 35.6892
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"Latitude of Tehran, Iran in decimal degrees.")
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(defconst calendar-bahai-tehran-longitude 51.3890
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"Longitude of Tehran, Iran in decimal degrees.")
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(defconst calendar-bahai-tehran-timezone 210
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"Tehran timezone offset in minutes (UTC+3:30 = 210 minutes).")
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(defconst calendar-bahai-reform-year 172
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"Bahá’í year when calendar reform took effect.
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From this year onwards, Naw-Rúz is determined by the vernal equinox
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as observed from Tehran, rather than being fixed at March 21.")
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(defun calendar-bahai-nawruz-for-gregorian-year (greg-year)
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"Calculate Gregorian date of Naw-Rúz for Gregorian year GREG-YEAR.
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Uses the vernal equinox as observed from Tehran to determine the date.
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The result is a Gregorian date (month day year).
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Bahá’í days run from sunset to sunset, so if the equinox occurs before
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sunset in Tehran, that day is Naw-Rúz; otherwise the next day is."
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(let* ((calendar-latitude calendar-bahai-tehran-latitude)
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(calendar-longitude calendar-bahai-tehran-longitude)
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(calendar-time-zone calendar-bahai-tehran-timezone)
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;; Disable DST for Tehran (Iran doesn't use DST anymore)
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(calendar-daylight-savings-starts nil)
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(calendar-daylight-savings-ends nil)
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;; Get vernal equinox date and time (k=0 for spring equinox)
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(equinox (solar-equinoxes/solstices 0 greg-year))
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(eq-month (car equinox))
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(eq-day-frac (cadr equinox))
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(eq-day (floor eq-day-frac))
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(eq-year (nth 2 equinox))
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(eq-date (list eq-month eq-day eq-year))
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;; Time of equinox in hours (fractional part of day * 24)
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(eq-time (* 24 (- eq-day-frac eq-day)))
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;; Get sunset time for this date in Tehran
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;; solar-sunrise-sunset returns ((sunrise-time zone) (sunset-time zone) daylight)
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(sunset-data (solar-sunrise-sunset eq-date))
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(sunset-time (car (cadr sunset-data))) ; sunset time in hours
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;; Tolerance in hours (2 minutes = 2/60 hours) to account for
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;; minor differences in astronomical calculations vs official tables.
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;; When the equinox is extremely close to sunset, small variations
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;; in ephemeris data or refraction calculations can affect the result.
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(tolerance (/ 2.0 60)))
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;; If equinox occurs clearly before sunset (by more than the tolerance),
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;; Naw-Rúz is that day. Otherwise, Naw-Rúz is the next day.
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(if (and sunset-time (< eq-time (- sunset-time tolerance)))
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eq-date
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(calendar-gregorian-from-absolute
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(1+ (calendar-absolute-from-gregorian eq-date))))))
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(defun calendar-bahai-nawruz (year)
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"Absolute date of Naw-Rúz (New Year) for Bahá’í YEAR.
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For years before 172 BE, uses fixed March 21.
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For years from 172 BE onwards, uses astronomical calculation of vernal equinox."
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(if (< year calendar-bahai-reform-year)
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;; Pre-reform: Naw-Rúz is always March 21
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;; Year N starts in Gregorian year 1843 + N
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(calendar-absolute-from-gregorian (list 3 21 (+ year 1843)))
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;; Post-reform: Calculate from vernal equinox
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(let ((greg-year (+ year 1843)))
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(calendar-absolute-from-gregorian
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(calendar-bahai-nawruz-for-gregorian-year greg-year)))))
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(defun calendar-bahai-twin-holy-birthdays-for-year (bahai-year)
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"Calculate Gregorian dates of the Twin Holy Birthdays for Bahá’í YEAR.
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Returns a list of two Gregorian dates: (BAB-DATE BAHA-DATE).
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The dates are determined by the eighth new moon after Naw-Rúz,
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calculated for Tehran's timezone. The first day following the
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eighth new moon is the Birth of the Báb, and the second day is
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the Birth of Bahá’u’lláh."
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(let* ((calendar-time-zone calendar-bahai-tehran-timezone)
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;; Disable DST for Tehran
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(calendar-daylight-savings-starts nil)
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(calendar-daylight-savings-ends nil)
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;; Get absolute date of Naw-Rúz for this Bahá’í year
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(nawruz-absolute (calendar-bahai-nawruz bahai-year))
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;; Naw-Rúz starts at sunset on this date in Tehran
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;; We need to find new moons that occur AFTER sunset on Naw-Rúz
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(nawruz-greg (calendar-gregorian-from-absolute nawruz-absolute))
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;; Get sunset time on Naw-Rúz in Tehran
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(nawruz-sunset-data (let ((calendar-latitude calendar-bahai-tehran-latitude)
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(calendar-longitude calendar-bahai-tehran-longitude))
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(solar-sunrise-sunset nawruz-greg)))
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(nawruz-sunset (or (car (cadr nawruz-sunset-data)) 18.0)) ; default 6pm
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;; Convert Naw-Rúz sunset to Julian day
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;; Absolute date is at midnight, add fraction for sunset time
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(nawruz-julian (+ (calendar-astro-from-absolute nawruz-absolute)
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(/ nawruz-sunset 24.0)))
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;; Find the 8th new moon after Naw-Rúz sunset
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(current-julian nawruz-julian)
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eighth-new-moon)
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;; Find 8 new moons after Naw-Rúz by iterating
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(dotimes (_ 8)
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(setq current-julian (lunar-new-moon-on-or-after current-julian))
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(setq eighth-new-moon current-julian)
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;; Move forward by at least one day to find the next new moon
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;; (lunar cycle is ~29.5 days, so +1 is safe)
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(setq current-julian (+ current-julian 1)))
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;; Convert the eighth new moon to absolute date and time
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(let* ((new-moon-abs-with-frac (calendar-astro-to-absolute eighth-new-moon))
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(new-moon-absolute (floor new-moon-abs-with-frac))
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(new-moon-time-frac (- new-moon-abs-with-frac new-moon-absolute))
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(new-moon-time-hours (* 24 new-moon-time-frac))
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(new-moon-greg (calendar-gregorian-from-absolute new-moon-absolute))
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;; Get sunset time in Tehran for the day of the new moon
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(sunset-data (let ((calendar-latitude calendar-bahai-tehran-latitude)
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(calendar-longitude calendar-bahai-tehran-longitude)
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(calendar-time-zone calendar-bahai-tehran-timezone))
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(solar-sunrise-sunset new-moon-greg)))
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;; solar-sunrise-sunset returns ((sunrise-time zone) (sunset-time zone) daylight)
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(sunset-time (car (cadr sunset-data)))
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;; Determine which civil day is the "first day following" the new moon
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;; In Bahá’í calendar, days run from sunset to sunset.
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;; If new moon occurs before sunset, the Bahá’í day starting at
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;; sunset that evening begins the "first day following"
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;; If new moon occurs after sunset, we're already in the next Bahá’í
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;; day, so the "first day following" starts at the next sunset
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(bab-absolute (if (and sunset-time (< new-moon-time-hours sunset-time))
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(1+ new-moon-absolute) ; Next civil day
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(+ new-moon-absolute 2))) ; Civil day after next
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(baha-absolute (1+ bab-absolute)))
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;; Return both dates as Gregorian dates
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(list (calendar-gregorian-from-absolute bab-absolute)
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(calendar-gregorian-from-absolute baha-absolute)))))
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(defun calendar-bahai-leap-year-p (year)
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"True if Bahá’í YEAR is a leap year in the Bahá’í calendar."
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(calendar-leap-year-p (+ year 1844)))
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"True if Bahá’í YEAR is a leap year in the Bahá’í calendar.
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For years before 172 BE, follows Gregorian leap year pattern.
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For years from 172 BE onwards, determined by whether Ayyám-i-Há has 5 days
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based on the gap between successive Naw-Rúz dates."
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(if (< year calendar-bahai-reform-year)
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;; Pre-reform: follows Gregorian pattern
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;; Ayyám-i-Há of year N falls in Gregorian February of year 1844 + N
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(calendar-leap-year-p (+ year 1844))
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;; Post-reform: 5 days of Ayyám-i-Há if the gap requires it
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;; A year has 5 Ayyám-i-Há days if this year's Naw-Rúz to next year's
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;; Naw-Rúz is 366 days (otherwise 365)
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(let ((this-nawruz (calendar-bahai-nawruz year))
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(next-nawruz (calendar-bahai-nawruz (1+ year))))
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(= (- next-nawruz this-nawruz) 366))))
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(defconst calendar-bahai-leap-base
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(+ (/ 1844 4) (- (/ 1844 100)) (/ 1844 400))
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@ -79,20 +237,45 @@ The absolute date is the number of days elapsed since the (imaginary)
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Gregorian date Sunday, December 31, 1 BC."
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(let* ((month (calendar-extract-month date))
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(day (calendar-extract-day date))
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(year (calendar-extract-year date))
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(prior-years (+ (1- year) 1844))
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(leap-days (- (+ (/ prior-years 4) ; leap days in prior years
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(- (/ prior-years 100))
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(/ prior-years 400))
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calendar-bahai-leap-base)))
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(+ (1- calendar-bahai-epoch) ; days before epoch
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(* 365 (1- year)) ; days in prior years
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leap-days
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(calendar-sum m 1 (< m month) 19)
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(if (= month 19)
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(if (calendar-bahai-leap-year-p year) 5 4)
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0)
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day))) ; days so far this month
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(year (calendar-extract-year date)))
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(if (< year calendar-bahai-reform-year)
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;; Pre-reform: use the old fixed calculation
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(let* ((prior-years (+ (1- year) 1844))
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(leap-days (- (+ (/ prior-years 4) ; leap days in prior years
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(- (/ prior-years 100))
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(/ prior-years 400))
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calendar-bahai-leap-base)))
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(+ (1- calendar-bahai-epoch) ; days before epoch
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(* 365 (1- year)) ; days in prior years
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leap-days
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(calendar-sum m 1 (< m month) 19)
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(if (= month 19)
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;; For Ayyám-i-Há (day <= 0), adjust by (ayyam-ha-days - 1)
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;; instead of ayyam-ha-days to match encoding
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(if (<= day 0)
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(1- (if (calendar-bahai-leap-year-p year) 5 4))
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(if (calendar-bahai-leap-year-p year) 5 4))
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0)
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day)) ; days so far this month
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;; Post-reform: use actual Naw-Rúz dates
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(let ((year-start (calendar-bahai-nawruz year))
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(ayyam-ha-days (if (calendar-bahai-leap-year-p year) 5 4)))
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(+ year-start
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-1 ; go back one day from start
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;; Add days for complete months
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(cond
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((< month 19)
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(+ (* 19 (1- month))
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day))
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;; Month 19, day <= 0: Ayyám-i-Há
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((<= day 0)
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(+ (* 19 18)
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(+ day (1- ayyam-ha-days))))
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;; Month 19, day > 0: month 'Alá'
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(t
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(+ (* 19 18)
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ayyam-ha-days
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day))))))))
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(defun calendar-bahai-from-absolute (date)
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"Bahá’í date (month day year) corresponding to the absolute DATE."
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@ -100,19 +283,40 @@ Gregorian date Sunday, December 31, 1 BC."
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(list 0 0 0) ; pre-Bahá’í date
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(let* ((greg (calendar-gregorian-from-absolute date))
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(gmonth (calendar-extract-month greg))
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(year (+ (- (calendar-extract-year greg) 1844)
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(gyear (calendar-extract-year greg))
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(gday (calendar-extract-day greg))
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;; Estimate the Bahá’í year
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(year (+ (- gyear 1844)
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(if (or (> gmonth 3)
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(and (= gmonth 3)
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(>= (calendar-extract-day greg) 21)))
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1 0)))
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(month ; search forward from Baha
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(1+ (calendar-sum m 1
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(> date (calendar-bahai-to-absolute (list m 19 year)))
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1)))
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(day ; calculate the day by subtraction
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(- date
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(1- (calendar-bahai-to-absolute (list month 1 year))))))
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(list month day year))))
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(and (= gmonth 3) (>= gday 15)))
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1 0))))
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;; Adjust year if needed based on actual Naw-Rúz
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(while (< date (calendar-bahai-nawruz year))
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(setq year (1- year)))
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(while (>= date (calendar-bahai-nawruz (1+ year)))
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(setq year (1+ year)))
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;; Now calculate month and day within the year
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(let* ((year-start (calendar-bahai-nawruz year))
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(days-in-year (- date year-start))
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(ayyam-ha-days (if (calendar-bahai-leap-year-p year) 5 4))
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month day)
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(cond
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;; In first 18 months (days 0-341)
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((< days-in-year (* 19 18))
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(setq month (1+ (/ days-in-year 19))
|
||||
day (1+ (% days-in-year 19))))
|
||||
;; In Ayyám-i-Há (days 342-345 or 342-346)
|
||||
((< days-in-year (+ (* 19 18) ayyam-ha-days))
|
||||
;; Encode Ayyám-i-Há as month 19 with day <= 0
|
||||
;; First day is -(ayyam-ha-days-1), last day is 0
|
||||
(let ((ayyam-day (- days-in-year (* 19 18))))
|
||||
(setq month 19
|
||||
day (- ayyam-day (1- ayyam-ha-days)))))
|
||||
;; In month 19 ('Alá')
|
||||
(t
|
||||
(setq month 19
|
||||
day (1+ (- days-in-year (* 19 18) ayyam-ha-days)))))
|
||||
(list month day year)))))
|
||||
|
||||
;;;###cal-autoload
|
||||
(defun calendar-bahai-date-string (&optional date)
|
||||
|
|
@ -221,27 +425,68 @@ list (((month day year) STRING)). Otherwise, returns nil."
|
|||
;;;###holiday-autoload
|
||||
(defun holiday-bahai-new-year ()
|
||||
"Holiday entry for the Bahá’í New Year, if visible in the calendar window."
|
||||
(holiday-fixed 3 21
|
||||
(format "Bahá’í New Year (Naw-Ruz) %d"
|
||||
(- displayed-year (1- 1844)))))
|
||||
(let* ((bahai-year (- displayed-year (1- 1844)))
|
||||
(nawruz-date (if (< bahai-year calendar-bahai-reform-year)
|
||||
;; Pre-reform: always March 21
|
||||
(list 3 21 displayed-year)
|
||||
;; Post-reform: calculate from equinox
|
||||
(calendar-bahai-nawruz-for-gregorian-year displayed-year))))
|
||||
(when (calendar-date-is-visible-p nawruz-date)
|
||||
(list (list nawruz-date
|
||||
(format "Bahá’í New Year (Naw-Ruz) %d" bahai-year))))))
|
||||
|
||||
;;;###holiday-autoload
|
||||
(defun holiday-bahai-twin-holy-birthdays ()
|
||||
"Holiday entries for the Twin Holy Birthdays, if visible in the calendar.
|
||||
The Birth of the Báb and Birth of Bahá’u’lláh are celebrated on
|
||||
consecutive days. From 172 BE onwards, these dates are determined
|
||||
by the eighth new moon after Naw-Rúz; before that, they were fixed
|
||||
at October 20 and November 12."
|
||||
(let* ((bahai-year (- displayed-year (1- 1844)))
|
||||
result)
|
||||
(if (>= bahai-year calendar-bahai-reform-year)
|
||||
;; Post-reform: calculate from eighth new moon
|
||||
(let* ((dates (calendar-bahai-twin-holy-birthdays-for-year bahai-year))
|
||||
(bab-date (car dates))
|
||||
(baha-date (cadr dates)))
|
||||
(when (calendar-date-is-visible-p bab-date)
|
||||
(push (list bab-date "Birth of the Báb") result))
|
||||
(when (calendar-date-is-visible-p baha-date)
|
||||
(push (list baha-date "Birth of Bahá’u’lláh") result)))
|
||||
;; Pre-reform: fixed dates
|
||||
(let ((bab-date (list 10 20 displayed-year))
|
||||
(baha-date (list 11 12 displayed-year)))
|
||||
(when (calendar-date-is-visible-p bab-date)
|
||||
(push (list bab-date "Birth of the Báb") result))
|
||||
(when (calendar-date-is-visible-p baha-date)
|
||||
(push (list baha-date "Birth of Bahá’u’lláh") result))))
|
||||
(nreverse result)))
|
||||
|
||||
;;;###holiday-autoload
|
||||
(defun holiday-bahai-ridvan (&optional all)
|
||||
"Holidays related to Ridvan, as visible in the calendar window.
|
||||
Only considers the first, ninth, and twelfth days, unless ALL or
|
||||
`calendar-bahai-all-holidays-flag' is non-nil."
|
||||
`calendar-bahai-all-holidays-flag' is non-nil.
|
||||
|
||||
Ridvan is a 12-day festival from 13 Jalál to 5 Jamál (Bahá’í months 2-3).
|
||||
In the reformed calendar (172 BE onwards), these dates shift relative to
|
||||
the Gregorian calendar based on when Naw-Rúz falls."
|
||||
(let ((ord ["First" "Second" "Third" "Fourth" "Fifth" "Sixth"
|
||||
"Seventh" "Eighth" "Ninth" "Tenth" "Eleventh" "Twelfth"])
|
||||
(show '(0 8 11))
|
||||
rid h)
|
||||
(if (or all calendar-bahai-all-holidays-flag)
|
||||
(setq show (number-sequence 0 11)))
|
||||
;; More trouble than it was worth...?
|
||||
(dolist (i show (nreverse rid))
|
||||
(if (setq h (holiday-fixed (if (< i 10) 4 5)
|
||||
(+ i (if (< i 10) 21 -9))
|
||||
(format "%s Day of Ridvan" (aref ord i))))
|
||||
(push (car h) rid)))))
|
||||
;; Ridvan spans months 2-3 in the Bahá’í calendar:
|
||||
;; Day 1 (i=0) = 13 Jalál = month 2, day 13
|
||||
;; Days 2-7 (i=1-6) = 14-19 Jalál = month 2, days 14-19
|
||||
;; Days 8-12 (i=7-11) = 1-5 Jamál = month 3, days 1-5
|
||||
(let ((month (if (< i 7) 2 3))
|
||||
(day (if (< i 7) (+ i 13) (- i 6))))
|
||||
(when (setq h (holiday-bahai month day
|
||||
(format "%s Day of Ridvan" (aref ord i))))
|
||||
(push (car h) rid))))))
|
||||
|
||||
(autoload 'diary-list-entries-1 "diary-lib")
|
||||
|
||||
|
|
@ -327,6 +572,231 @@ Prefix argument ARG will make the entry nonmarking."
|
|||
(format "Bahá’í date: %s" (calendar-bahai-date-string date)))
|
||||
|
||||
|
||||
;;; ======================================================================
|
||||
;;; Verification and Testing
|
||||
;;; ======================================================================
|
||||
|
||||
;; The following code verifies the astronomical calculations against
|
||||
;; official dates published by the Bahá’í World Centre.
|
||||
;;
|
||||
;; BACKGROUND: 2014 Calendar Reform
|
||||
;; --------------------------------
|
||||
;; On 10 July 2014, the Universal House of Justice announced provisions
|
||||
;; for the uniform implementation of the Badí' calendar, effective from
|
||||
;; Naw-Rúz 172 BE (March 2015). The key provisions are:
|
||||
;;
|
||||
;; 1. NAW-RÚZ DETERMINATION:
|
||||
;; "The Festival of Naw-Rúz falleth on the day that the sun entereth
|
||||
;; the sign of Aries, even should this occur no more than one minute
|
||||
;; before sunset." Tehran is the reference point for determining the
|
||||
;; moment of the vernal equinox. If the equinox occurs before sunset
|
||||
;; in Tehran, that day is Naw-Rúz; otherwise, the following day is.
|
||||
;;
|
||||
;; 2. TWIN HOLY BIRTHDAYS:
|
||||
;; "They will now be observed on the first and the second day
|
||||
;; following the occurrence of the eighth new moon after Naw-Rúz,
|
||||
;; as determined in advance by astronomical tables using Ṭihrán as
|
||||
;; the point of reference."
|
||||
;;
|
||||
;; VERIFICATION APPROACH
|
||||
;; ---------------------
|
||||
;; The functions below compare calculated dates against official data
|
||||
;; from the Bahá’í World Centre, covering the 50-year period from
|
||||
;; 172 BE (2015 CE) to 221 BE (2064 CE). This data was extracted from
|
||||
;; the official ICS calendar file distributed by the Bahá’í World Centre.
|
||||
;;
|
||||
;; The verification confirms:
|
||||
;; - Naw-Rúz dates: Calculated using `solar-equinoxes/solstices' for the
|
||||
;; vernal equinox and `solar-sunrise-sunset' for Tehran sunset times.
|
||||
;; - Twin Holy Birthdays: Calculated using `lunar-new-moon-on-or-after'
|
||||
;; to find the eighth new moon after Naw-Rúz.
|
||||
;;
|
||||
;; To run the verification:
|
||||
;; M-x calendar-bahai-verify-calculations RET
|
||||
|
||||
(defconst calendar-bahai--nawruz-reference-dates
|
||||
'((2015 3 21) (2016 3 20) (2017 3 20) (2018 3 21) (2019 3 21)
|
||||
(2020 3 20) (2021 3 20) (2022 3 21) (2023 3 21) (2024 3 20)
|
||||
(2025 3 20) (2026 3 21) (2027 3 21) (2028 3 20) (2029 3 20)
|
||||
(2030 3 20) (2031 3 21) (2032 3 20) (2033 3 20) (2034 3 20)
|
||||
(2035 3 21) (2036 3 20) (2037 3 20) (2038 3 20) (2039 3 21)
|
||||
(2040 3 20) (2041 3 20) (2042 3 20) (2043 3 21) (2044 3 20)
|
||||
(2045 3 20) (2046 3 20) (2047 3 21) (2048 3 20) (2049 3 20)
|
||||
(2050 3 20) (2051 3 21) (2052 3 20) (2053 3 20) (2054 3 20)
|
||||
(2055 3 21) (2056 3 20) (2057 3 20) (2058 3 20) (2059 3 20)
|
||||
(2060 3 20) (2061 3 20) (2062 3 20) (2063 3 20) (2064 3 20))
|
||||
"Official Naw-Rúz dates from the Bahá’í World Centre (2015-2064).
|
||||
Each entry is (GREGORIAN-YEAR MONTH DAY). These dates are extracted
|
||||
from the official ICS calendar file and serve as the authoritative
|
||||
reference for verifying the astronomical calculations.
|
||||
|
||||
The dates show that Naw-Rúz falls on March 20 or 21, depending on
|
||||
when the vernal equinox occurs relative to sunset in Tehran.")
|
||||
|
||||
(defconst calendar-bahai--twin-birthdays-reference-dates
|
||||
'(;; (GREG-YEAR BAB-MONTH BAB-DAY BAHA-MONTH BAHA-DAY)
|
||||
(2015 11 13 11 14) (2016 11 1 11 2) (2017 10 21 10 22)
|
||||
(2018 11 9 11 10) (2019 10 29 10 30) (2020 10 18 10 19)
|
||||
(2021 11 6 11 7) (2022 10 26 10 27) (2023 10 16 10 17)
|
||||
(2024 11 2 11 3) (2025 10 22 10 23) (2026 11 10 11 11)
|
||||
(2027 10 30 10 31) (2028 10 19 10 20) (2029 11 7 11 8)
|
||||
(2030 10 28 10 29) (2031 10 17 10 18) (2032 11 4 11 5)
|
||||
(2033 10 24 10 25) (2034 11 12 11 13) (2035 11 1 11 2)
|
||||
(2036 10 20 10 21) (2037 11 8 11 9) (2038 10 29 10 30)
|
||||
(2039 10 19 10 20) (2040 11 6 11 7) (2041 10 26 10 27)
|
||||
(2042 10 15 10 16) (2043 11 3 11 4) (2044 10 22 10 23)
|
||||
(2045 11 10 11 11) (2046 10 30 10 31) (2047 10 20 10 21)
|
||||
(2048 11 7 11 8) (2049 10 28 10 29) (2050 10 17 10 18)
|
||||
(2051 11 5 11 6) (2052 10 24 10 25) (2053 11 11 11 12)
|
||||
(2054 11 1 11 2) (2055 10 21 10 22) (2056 11 8 11 9)
|
||||
(2057 10 29 10 30) (2058 10 18 10 19) (2059 11 6 11 7)
|
||||
(2060 10 25 10 26) (2061 10 14 10 15) (2062 11 2 11 3)
|
||||
(2063 10 23 10 24) (2064 11 10 11 11))
|
||||
"Official Twin Holy Birthday dates from the Bahá’í World Centre (2015-2064).
|
||||
Each entry is (GREGORIAN-YEAR BAB-MONTH BAB-DAY BAHA-MONTH BAHA-DAY).
|
||||
|
||||
The Birth of the Báb and the Birth of Bahá’u’lláh are celebrated on
|
||||
consecutive days, determined by the eighth new moon after Naw-Rúz.
|
||||
These dates move through the Gregorian calendar, typically falling
|
||||
between mid-October and mid-November (Bahá’í months of Mashíyyat,
|
||||
'Ilm, and Qudrat).")
|
||||
|
||||
(defun calendar-bahai--verify-nawruz ()
|
||||
"Verify Naw-Rúz calculations against official reference dates.
|
||||
Returns a plist with :total, :correct, and :errors keys."
|
||||
(let ((total 0)
|
||||
(correct 0)
|
||||
(errors nil))
|
||||
(dolist (entry calendar-bahai--nawruz-reference-dates)
|
||||
(let* ((greg-year (nth 0 entry))
|
||||
(expected-month (nth 1 entry))
|
||||
(expected-day (nth 2 entry))
|
||||
(expected (list expected-month expected-day greg-year))
|
||||
(computed (calendar-bahai-nawruz-for-gregorian-year greg-year)))
|
||||
(setq total (1+ total))
|
||||
(if (equal computed expected)
|
||||
(setq correct (1+ correct))
|
||||
(push (list greg-year expected computed) errors))))
|
||||
(list :total total :correct correct :errors (nreverse errors))))
|
||||
|
||||
(defun calendar-bahai--verify-twin-birthdays ()
|
||||
"Verify Twin Holy Birthday calculations against official reference dates.
|
||||
Returns a plist with :total, :bab-correct, :baha-correct, and :errors keys."
|
||||
(let ((total 0)
|
||||
(bab-correct 0)
|
||||
(baha-correct 0)
|
||||
(errors nil))
|
||||
(dolist (entry calendar-bahai--twin-birthdays-reference-dates)
|
||||
(let* ((greg-year (nth 0 entry))
|
||||
(bahai-year (- greg-year (1- 1844)))
|
||||
(expected-bab (list (nth 1 entry) (nth 2 entry) greg-year))
|
||||
(expected-baha (list (nth 3 entry) (nth 4 entry) greg-year)))
|
||||
;; Only verify from reform year onwards
|
||||
(when (>= bahai-year calendar-bahai-reform-year)
|
||||
(setq total (1+ total))
|
||||
(let* ((computed (calendar-bahai-twin-holy-birthdays-for-year bahai-year))
|
||||
(computed-bab (car computed))
|
||||
(computed-baha (cadr computed)))
|
||||
(if (equal computed-bab expected-bab)
|
||||
(setq bab-correct (1+ bab-correct))
|
||||
(push (list greg-year "Báb" expected-bab computed-bab) errors))
|
||||
(if (equal computed-baha expected-baha)
|
||||
(setq baha-correct (1+ baha-correct))
|
||||
(push (list greg-year "Bahá’u’lláh" expected-baha computed-baha)
|
||||
errors))))))
|
||||
(list :total total
|
||||
:bab-correct bab-correct
|
||||
:baha-correct baha-correct
|
||||
:errors (nreverse errors))))
|
||||
|
||||
(defun calendar-bahai-verify-calculations ()
|
||||
"Verify Bahá’í calendar calculations against official reference dates.
|
||||
This function compares the astronomical calculations for Naw-Rúz and
|
||||
the Twin Holy Birthdays against official dates from the Bahá’í World
|
||||
Centre for the period 172-221 BE (2015-2064 CE).
|
||||
|
||||
The verification tests:
|
||||
1. Naw-Rúz dates - calculated from the vernal equinox relative to
|
||||
sunset in Tehran.
|
||||
2. Birth of the Báb dates - the first day following the eighth new
|
||||
moon after Naw-Rúz.
|
||||
3. Birth of Bahá’u’lláh dates - the second day following the eighth
|
||||
new moon after Naw-Rúz.
|
||||
|
||||
Results are displayed in the *Bahá’í Calendar Verification* buffer."
|
||||
(interactive)
|
||||
(let* ((nawruz-results (calendar-bahai--verify-nawruz))
|
||||
(twin-results (calendar-bahai--verify-twin-birthdays))
|
||||
(buf (get-buffer-create "*Bahá’í Calendar Verification*")))
|
||||
(with-current-buffer buf
|
||||
(erase-buffer)
|
||||
|
||||
(insert "This report verifies the astronomical calculations against\n")
|
||||
(insert "official dates from the Bahá’í World Centre (172-221 BE).\n\n")
|
||||
|
||||
;; Naw-Rúz results
|
||||
(insert "───────────────────────────────────────────────────────────────\n")
|
||||
(insert "NAW-RÚZ VERIFICATION\n")
|
||||
(insert "───────────────────────────────────────────────────────────────\n")
|
||||
(insert (format " Total years tested: %d\n" (plist-get nawruz-results :total)))
|
||||
(insert (format " Correct: %d\n" (plist-get nawruz-results :correct)))
|
||||
(insert (format " Errors: %d\n"
|
||||
(length (plist-get nawruz-results :errors))))
|
||||
(when (plist-get nawruz-results :errors)
|
||||
(insert "\n Discrepancies:\n")
|
||||
(dolist (err (plist-get nawruz-results :errors))
|
||||
(insert (format " %d: expected %S, calculated %S\n"
|
||||
(nth 0 err) (nth 1 err) (nth 2 err)))))
|
||||
(insert "\n")
|
||||
|
||||
;; Twin Holy Birthdays results
|
||||
(insert "───────────────────────────────────────────────────────────────\n")
|
||||
(insert "TWIN HOLY BIRTHDAYS VERIFICATION\n")
|
||||
(insert "───────────────────────────────────────────────────────────────\n")
|
||||
(insert (format " Total years tested: %d\n"
|
||||
(plist-get twin-results :total)))
|
||||
(insert (format " Birth of Báb correct: %d\n"
|
||||
(plist-get twin-results :bab-correct)))
|
||||
(insert (format " Birth of Bahá’u’lláh correct: %d\n"
|
||||
(plist-get twin-results :baha-correct)))
|
||||
(insert (format " Errors: %d\n"
|
||||
(length (plist-get twin-results :errors))))
|
||||
(when (plist-get twin-results :errors)
|
||||
(insert "\n Discrepancies:\n")
|
||||
(dolist (err (plist-get twin-results :errors))
|
||||
(insert (format " %d %s: expected %S, calculated %S\n"
|
||||
(nth 0 err) (nth 1 err) (nth 2 err) (nth 3 err)))))
|
||||
(insert "\n")
|
||||
|
||||
;; Summary
|
||||
(insert "───────────────────────────────────────────────────────────────\n")
|
||||
(insert "SUMMARY\n")
|
||||
(insert "───────────────────────────────────────────────────────────────\n")
|
||||
(let ((total-errors (+ (length (plist-get nawruz-results :errors))
|
||||
(length (plist-get twin-results :errors)))))
|
||||
(if (zerop total-errors)
|
||||
(progn
|
||||
(insert " All calculations match official dates!\n\n")
|
||||
(insert " The astronomical algorithms correctly compute:\n")
|
||||
(insert " • Naw-Rúz from the vernal equinox/sunset in Tehran\n")
|
||||
(insert " • Twin Holy Birthdays from the 8th new moon after Naw-Rúz\n"))
|
||||
(insert (format " ✗ Total discrepancies: %d\n" total-errors))
|
||||
(insert " Review the errors above for details.\n"))))
|
||||
|
||||
(display-buffer buf)
|
||||
;; Return results for programmatic use
|
||||
(list :nawruz nawruz-results :twin-birthdays twin-results)))
|
||||
|
||||
(defun calendar-bahai-run-tests ()
|
||||
"Run verification tests and return t if all pass, nil otherwise.
|
||||
This function is suitable for use in automated testing."
|
||||
(let* ((nawruz-results (calendar-bahai--verify-nawruz))
|
||||
(twin-results (calendar-bahai--verify-twin-birthdays))
|
||||
(nawruz-ok (zerop (length (plist-get nawruz-results :errors))))
|
||||
(twin-ok (zerop (length (plist-get twin-results :errors)))))
|
||||
(and nawruz-ok twin-ok)))
|
||||
|
||||
|
||||
(provide 'cal-bahai)
|
||||
|
||||
;;; cal-bahai.el ends here
|
||||
|
|
|
|||
|
|
@ -192,15 +192,14 @@ or `customize-option'."
|
|||
(defcustom holiday-bahai-holidays
|
||||
'((holiday-bahai-new-year)
|
||||
(holiday-bahai-ridvan) ; respects calendar-bahai-all-holidays-flag
|
||||
(holiday-fixed 5 23 "Declaration of the Báb")
|
||||
(holiday-fixed 5 29 "Ascension of Bahá’u’lláh")
|
||||
(holiday-fixed 7 9 "Martyrdom of the Báb")
|
||||
(holiday-fixed 10 20 "Birth of the Báb")
|
||||
(holiday-fixed 11 12 "Birth of Bahá’u’lláh")
|
||||
(holiday-bahai 4 8 "Declaration of the Báb")
|
||||
(holiday-bahai 4 13 "Ascension of Bahá’u’lláh")
|
||||
(holiday-bahai 6 17 "Martyrdom of the Báb")
|
||||
(holiday-bahai-twin-holy-birthdays) ; dates vary based on lunar calendar
|
||||
(if calendar-bahai-all-holidays-flag
|
||||
(append
|
||||
(holiday-fixed 11 26 "Day of the Covenant")
|
||||
(holiday-fixed 11 28 "Ascension of `Abdu’l-Bahá"))))
|
||||
(holiday-bahai 14 4 "Day of the Covenant")
|
||||
(holiday-bahai 14 6 "Ascension of ‘Abdu’l-Bahá"))))
|
||||
"Bahá’í holidays.
|
||||
See the documentation for `calendar-holidays' for details."
|
||||
:set #'holidays--set-calendar-holidays
|
||||
|
|
|
|||
Loading…
Reference in a new issue