%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%								%
%	   TeX algorithm to compute an Easter date		%
%	  =========================================		%
%								%
% File: Easter2.tex v 2.5 02-10-16 23:22:50			%
% Author: (c) 1995, 2002 Stanislav Brabec utx@penguin.cz	%
%								%
% Copyright: Easter2.tex is freely distributable as a sample of	%
%	     compact astronomic computations in plain TeX	%
%								%
% Usage:							%
% virtex [&fmt] [\year[=]year] \input Easter2			%
%  (writes result to Easter2.dvi, not console, sorry)		%
%								%
% Years available: 1900-2099					%
%								%
% Based on Easter algorithm of Carl Friedrich Gauss.		%
% Warning: Trying to understand the algorithm can take a very	%
%	long time and can cause a headache! Don't try it.	%
% ... (And if you find a shorter algorithm, let me know!)	%
% Note: I have also multi language version. 			%
%								%
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

\def~#1{\catcode`#113}~:\let:\let~+:+\advance~`:`\year~$
:$\newcount~^:^\def~[:[\ifnum~?:?\the~]:]\fi~*:*\multiply
~/~'~(~)~;$($'$)$;^/#1#2{(#1\divide(#2*(-#2+#1(}'`/'{19}*'19
+'24/'{30})5;`/;4*;2+);;`/;7*;4+);;'*;6+);/)7+)'+)21
[)>55+)-7](31^:{; }^'{+)1 [)>(+)-(^:{/ }]}'^*{}[)=(^*{:}]^~{?)}
^;{March}^/{April}:~\ and '*~, ?`
\end