Function: calendar-mayan-tzolkin-haab-on-or-before

calendar-mayan-tzolkin-haab-on-or-before is a byte-compiled function defined in cal-mayan.el.gz.

Signature

(calendar-mayan-tzolkin-haab-on-or-before TZOLKIN-DATE HAAB-DATE DATE)

Documentation

Absolute date that is Mayan TZOLKIN-DATE and HAAB-DATE.

Latest such date on or before DATE. Returns nil if such a tzolkin-haab combination is impossible.

Source Code

;; Defined in /usr/src/emacs/lisp/calendar/cal-mayan.el.gz
(defun calendar-mayan-tzolkin-haab-on-or-before (tzolkin-date haab-date date)
  "Absolute date that is Mayan TZOLKIN-DATE and HAAB-DATE.
Latest such date on or before DATE.
Returns nil if such a tzolkin-haab combination is impossible."
  (let* ((haab-difference
          (calendar-mayan-haab-difference
           (calendar-mayan-haab-from-absolute 0)
           haab-date))
         (tzolkin-difference
          (calendar-mayan-tzolkin-difference
           (calendar-mayan-tzolkin-from-absolute 0)
           tzolkin-date))
         (difference (- tzolkin-difference haab-difference)))
    (if (zerop (% difference 5))
        (- date
           (mod (- date
                   (+ haab-difference (* 365 difference)))
                18980))
      nil)))