Function: calendar-french-leap-year-p

calendar-french-leap-year-p is a byte-compiled function defined in cal-french.el.gz.

Signature

(calendar-french-leap-year-p YEAR)

Documentation

True if YEAR is a leap year on the French Revolutionary calendar.

For Gregorian years 1793 to 1805, the years of actual operation of the calendar, follows historical practice based on equinoxes (years 3, 7, and 11 were leap years; 15 and 20 would have been leap years). For later 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.

Source Code

;; Defined in /usr/src/emacs/lisp/calendar/cal-french.el.gz
(defun calendar-french-leap-year-p (year)
  "True if YEAR is a leap year on the French Revolutionary calendar.
For Gregorian years 1793 to 1805, the years of actual operation of the
calendar, follows historical practice based on equinoxes (years 3, 7,
and 11 were leap years; 15 and 20 would have been leap years).  For later
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
           (zerop (% year 4))
           (not (memq (% year 400) '(100 200 300)))
           (not (zerop (% year 4000))))))