From: servando garcia <garcia.servando@...>
Date: 2007-04-09T04:59:34+09:00
Subject: Re: Proposal: Yet another Date method

If we are taking a vote on this I vote YES
On Sun, 2007-04-08 at 22:05 +0900, Bertram Scharpf wrote:
> Hi,
> 
> I would like the Date class to be extended by this:
> 
>   require "date"
>   
>   class Date
>     class <<self
>       def easter_western year
>         # This is after Donald E. Knuth and it works for both
>         # Julian (before 1583) and Gregorian (after 1582) calendars.
>         g = year%19 + 1                   # golden number
>         c = year/100 + 1                  # century
>         x = (3*c/4) - 12                  # corrections
>         z = (8*c+5)/25 - 5
>         d = 5*year/4 - x - 10             # March((-d)%7)th is Sunday
>         e = (11*g + 20 + z - x) % 30      # moon phase
>         e += 1 if e == 25 and g > 11 or e == 24
>         n = 44 - e                        # full moon
>         n += 30 if n < 21
>         month = 3
>         day = n+7 - (d+n)%7
>         if day > 31 then
>           month +=  1
>           day   -= 31
>         end
>         civil year, month, day
>       end
>       alias easter easter_western
>     end
>   end
> 
> I tested it with all easter date tables I found on the web
> in German, English and French.
> 
> Happy Easter!
> 
> Bertram
> 
>