Function: holiday-easter-etc-abs

holiday-easter-etc-abs is a byte-compiled function defined in holidays.el.gz.

Signature

(holiday-easter-etc-abs Y)

Documentation

Return the absolute date of Easter in Year.

Source Code

;; Defined in /usr/src/emacs/lisp/calendar/holidays.el.gz
(defun holiday-easter-etc-abs (y)
  "Return the absolute date of Easter in Year."
  (let* ((century (1+ (/ y 100)))
         (shifted-epact               ; age of moon for April 5...
          (% (+ 14 (* 11 (% y 19)) ; ...by Nicaean rule
                (-     ; ...corrected for the Gregorian century rule
                 (/ (* 3 century) 4))
                (/       ; ...corrected for Metonic cycle inaccuracy
                 (+ 5 (* 8 century)) 25)
                (* 30 century))       ; keeps value positive
             30))
         (adjusted-epact              ; adjust for 29.5 day month
          (if (or (zerop shifted-epact)
                  (and (= shifted-epact 1) (< 10 (% y 19))))
              (1+ shifted-epact)
            shifted-epact))
         (paschal-moon ; day after the full moon on or after March 21
          (- (calendar-absolute-from-gregorian (list 4 19 y))
             adjusted-epact))
         (abs-easter (calendar-dayname-on-or-before 0 (+ paschal-moon 7))))
    abs-easter))