Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!ames!ncar!tank!uxc!uxc.cso.uiuc.edu!m.cs.uiuc.edu!reingold
From: reingold@m.cs.uiuc.edu
Newsgroups: comp.emacs
Subject: Re: calendar.el
Message-ID: <4300042@m.cs.uiuc.edu>
Date: 4 Apr 89 13:24:00 GMT
References: <4300041@m.cs.uiuc.edu>
Lines: 84
Nf-ID: #R:m.cs.uiuc.edu:4300041:m.cs.uiuc.edu:4300042:000:3177
Nf-From: m.cs.uiuc.edu!reingold    Apr  4 08:24:00 1989


It was reported to me that the message was too big and the last few lines
were lost.  A complete copy can be obtained by anonymous ftp from
a.cs.uiuc.edu.  In any case, here are the last few lines.  (There is
some overlap--check!)

----------------------------------------------------------------------
(defun hebrew-calendar-leap-year-p (year)
  "Returns t if YEAR+3761 is a leap year."
  (memq
   (years-into-hebrew-calendar-cycle year)
   (list 0 3 6 8 11 14 17)))

(defun hebrew-calendar-long-heshvan-p (year)
  "Returns t if Heshvan is long in YEAR+3761."
   (if (hebrew-calendar-leap-year-p year)
       (= (-
           (hebrew-calendar-new-year-day (1+ year))
           (hebrew-calendar-new-year-day year)) 385)
     (= (-
         (hebrew-calendar-new-year-day (1+ year))
         (hebrew-calendar-new-year-day year)) 355)))

(defun hebrew-calendar-short-kislev-p (year)
  "Returns t if Kislev is short in YEAR+3761."
   (if (hebrew-calendar-leap-year-p year)
       (= (-
           (hebrew-calendar-new-year-day (1+ year))
           (hebrew-calendar-new-year-day year)) 383)
     (= (-
         (hebrew-calendar-new-year-day (1+ year))
         (hebrew-calendar-new-year-day year)) 353)))

(defun hebrew-calendar-last-day-of-month (month year)
  "The last day of MONTH in YEAR+3761."
  (if (or (memq month (list 2 4 6 10 13))
          (and (= month 12) (not (hebrew-calendar-leap-year-p year)))
          (and (= month 8) (not (hebrew-calendar-long-heshvan-p year)))
          (and (= month 9) (hebrew-calendar-short-kislev-p year)))
      29
    30))

(defun hebrew-calendar-date-beyond-date (days month year)
  "Returns the Hebrew date that is DAYS beyond the start of MONTH, YEAR+3761.
That date must be in the same year."
  (let ((len (hebrew-calendar-last-day-of-month month year)))
    (while (> days len) 
      (setq days (- days len))
      (setq month (1+ (% month (hebrew-calendar-last-month-of-year year))))
      (setq len (hebrew-calendar-last-day-of-month month year))))
  (list days month year))

(defun hebrew-calendar-days-from-tishri (days month year)
  "Number of days, inclusive, from 1 Tishri to DAYS, MONTH, YEAR+3761."
  (while (/= month 7)
    (setq month
          (if (= month 1)
              (hebrew-calendar-last-month-of-year year)
            (1- month)))
    (setq days (+ days (hebrew-calendar-last-day-of-month month year))))
  days)

(defun hebrew-calendar-year-length (year)
  "The number of days in Hebrew calendar YEAR+3761."
  (- (hebrew-calendar-new-year-day year)
     (hebrew-calendar-new-year-day (1- year))))

(defun hebrew-calendar-last-month-of-year (year)
  "The last month of the Hebrew calendar YEAR+3761."
  (if (hebrew-calendar-leap-year-p year)
      13
    12))

(defun calendar-absolute-from-hebrew (date)
  "Absolute date of Hebrew DATE.
The absolute date is the number of days elapsed since the (imaginary)
Gregorian date Sunday, December 31, 1 BC."
  (let ((month (extract-calendar-month date))
        (day (extract-calendar-day date))
        (year (- (extract-calendar-year date) 3761)))
    (+
     -1
     (hebrew-calendar-new-year-day year)
     (hebrew-calendar-days-from-tishri day month year))))