From: Jeremy McAnally <jeremymcanally@...>
Date: 2007-04-09T11:44:08+09:00
Subject: Re: Proposal: Yet another Date method

I wrote something that tests for Easter, Christmas, 4th of July, and
so on wrapped into a method called "is_national_holiday?" that I
planned on releasing as a gem, but I never did...I still have it if
you actually need something that doees this.

--Jeremy

On 4/8/07, Bertram Scharpf <lists@bertram-scharpf.de> 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
>
>
> --
> Bertram Scharpf
> Stuttgart, Deutschland/Germany
> http://www.bertram-scharpf.de
>
>


-- 
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