Re: Calculating Easter
- To: mathgroup at smc.vnet.net
- Subject: [mg40730] Re: [mg40670] Calculating Easter
- From: David Terr <dterr at wolfram.com>
- Date: Tue, 15 Apr 2003 03:59:06 -0400 (EDT)
- Organization: WRI
- References: <200304120713.DAA21412@smc.vnet.net>
- Sender: owner-wri-mathgroup at wolfram.com
Will Self wrote:
>An example of the function below is
>
>easter[2003] --->
>In the year 2003, Easter falls on April 20.
>
>
>Press, 1965, page 168:
>"...we shall give a purely numerical rule -- subject to no exceptions
>of any kind -- which calculates the date of Easter from a knowledge
>only of the year number..."
>
>I have retained O'Beirne's same variable names, except that I added
>the variable nn.
>
>easter[year_] :=
> Module[{x = year, b, c, d, e, g, h, i, k, mu, lambda, n, p, nn},
> a = Mod[x, 19];
> b = Quotient[x, 100];
> c = Mod[x, 100];
> d = Quotient[b, 4];
> e = Mod[b, 4];
> g = Quotient[8b + 13, 25];
> h = Mod[19a + b - d - g + 15, 30];
> mu = Quotient[a + 11h, 319];
> i = Quotient[c, 4];
> k = Mod[c, 4];
> lambda = Mod[2e + 2i - k - h + mu + 32, 7];
> n = Quotient[h - mu + lambda + 90, 25];
> p = Mod[h - mu + lambda + n + 19, 32];
> nn = Switch[n, 3, "March ", 4, "April "];
> Print[
> "In the year " <> ToString[x] <> ", Easter falls on " <> nn <>
> ToString[p] <> "."];]
>
Interesting. I wonder how well that formula matches the moon's phases.
I'd imagine after some time it'd be off, not that I really care or
anything! (I don't expect people will still be celebrating Easter in the
year 10,000 for instance.)
David
- References:
- Calculating Easter
- From: wself@msubillings.edu (Will Self)
- Calculating Easter