(defun coptic-calendar-last-day-of-month (month year)
"Return last day of MONTH, YEAR on the Coptic calendar.
The 13th month is not really a month, but the 5 (6 in leap years) day period of
-Nisi (Kebus) at the end of the year."
+Nisi (Kebus) at the end of the year."
(if (< month 13)
30
(if (coptic-calendar-leap-year-p year)
(let ((month (extract-calendar-month date))
(day (extract-calendar-day date))
(year (extract-calendar-year date)))
- (+ (1- coptic-calendar-epoch);; Days before start of calendar
- (* 365 (1- year)) ;; Days in prior years
- (/ year 4) ;; Leap days in prior years
- (* 30 (1- month)) ;; Days in prior months this year
- day))) ;; Days so far this month
+ (+ (1- coptic-calendar-epoch) ; days before start of calendar
+ (* 365 (1- year)) ; days in prior years
+ (/ year 4) ; leap days in prior years
+ (* 30 (1- month)) ; days in prior months this year
+ day))) ; days so far this month
(defun calendar-coptic-from-absolute (date)
The absolute date is the number of days elapsed since the imaginary
Gregorian date Sunday, December 31, 1 BC."
(if (< date coptic-calendar-epoch)
- (list 0 0 0);; pre-Coptic date
+ (list 0 0 0) ; pre-Coptic date
(let* ((approx (/ (- date coptic-calendar-epoch)
- 366)) ;; Approximation from below.
- (year ;; Search forward from the approximation.
+ 366)) ; approximation from below
+ (year ; search forward from the approximation
(+ approx
(calendar-sum y approx
(>= date (calendar-absolute-from-coptic (list 1 1 (1+ y))))
1)))
- (month ;; Search forward from Tot.
+ (month ; search forward from Tot
(1+ (calendar-sum m 1
(> date
(calendar-absolute-from-coptic
(coptic-calendar-last-day-of-month m year)
year)))
1)))
- (day ;; Calculate the day by subtraction.
+ (day ; calculate the day by subtraction
(- date
(1- (calendar-absolute-from-coptic (list month 1 year))))))
(list month day year))))
years uses the proposed rule of Romme (never adopted)--leap years fall every
four years except century years not divisible 400 and century years that are
multiples of 4000."
- (or (memq year '(3 7 11));; Actual practice--based on equinoxes
- (memq year '(15 20)) ;; Anticipated practice--based on equinoxes
- (and (> year 20) ;; Romme's proposal--never adopted
+ (or (memq year '(3 7 11)) ; actual practice--based on equinoxes
+ (memq year '(15 20)) ; anticipated practice--based on equinoxes
+ (and (> year 20) ; Romme's proposal--never adopted
(zerop (% year 4))
(not (memq (% year 400) '(100 200 300)))
(not (zerop (% year 4000))))))
(let ((month (extract-calendar-month date))
(day (extract-calendar-day date))
(year (extract-calendar-year date)))
- (+ (* 365 (1- year));; Days in prior years
- ;; Leap days in prior years
+ (+ (* 365 (1- year)) ; days in prior years
+ ;; Leap days in prior years.
(if (< year 20)
- (/ year 4);; Actual and anticipated practice (years 3, 7, 11, 15)
- ;; Romme's proposed rule (using the Principle of Inclusion/Exclusion)
- (+ (/ (1- year) 4);; Luckily, there were 4 leap years before year 20
+ (/ year 4) ; actual and anticipated practice (years 3, 7, 11, 15)
+ ;; Romme's proposed rule (using the Principle of Inclusion/Exclusion).
+ (+ (/ (1- year) 4) ; luckily, there were 4 leap years before year 20
(- (/ (1- year) 100))
(/ (1- year) 400)
(- (/ (1- year) 4000))))
- (* 30 (1- month));; Days in prior months this year
- day;; Days so far this month
- (1- french-calendar-epoch))));; Days before start of calendar
+ (* 30 (1- month)) ; days in prior months this year
+ day ; days so far this month
+ (1- french-calendar-epoch)))) ; days before start of calendar
(defun calendar-french-from-absolute (date)
"Compute the French Revolutionary equivalent for absolute date DATE.
The absolute date is the number of days elapsed since the
\(imaginary) Gregorian date Sunday, December 31, 1 BC."
(if (< date french-calendar-epoch)
- (list 0 0 0);; pre-French Revolutionary date
- (let* ((approx ;; Approximation from below.
+ (list 0 0 0) ; pre-French Revolutionary date
+ (let* ((approx ; approximation from below
(/ (- date french-calendar-epoch) 366))
- (year ;; Search forward from the approximation.
+ (year ; search forward from the approximation
(+ approx
(calendar-sum y approx
(>= date (calendar-absolute-from-french (list 1 1 (1+ y))))
1)))
- (month ;; Search forward from Vendemiaire.
+ (month ; search forward from Vendemiaire
(1+ (calendar-sum m 1
(> date
(calendar-absolute-from-french
(french-calendar-last-day-of-month m year)
year)))
1)))
- (day ;; Calculate the day by subtraction.
+ (day ; calculate the day by subtraction
(- date
(1- (calendar-absolute-from-french (list month 1 year))))))
(list month day year))))
(lambda (x) (concat "Jour " x))
french-calendar-special-days-array)
(reverse
- (cdr;; we don't want rev. day in a non-leap yr.
+ (cdr ; we don't want rev. day in a non-leap yr
(reverse
(mapcar
(lambda (x)