Easter date algorithms (c) Henk Reints

Gregorian algorithm by Henk Reints.

Valid for any year since 1583.

This is actually a variant of the Lilius/Clavius algorithm. I have only reorganised it in an attempt to make it as compact as possible (for example by moving some constants to other places).

 
A = year MOD 19
 
 
 
B = year DIV 100
 
 
 
C = (3 x B - 5) DIV 4
 
 
 
D = ( (12 + 11 x A + (8 x B + 13) DIV 25 - C) MOD 30 + 30) MOD 30
 
 
 
if  D = 0  or  (D = 1  and  A > 10)  then  E = 56 - D  else  E = 57 - D
 
 
 
result = E - (E + (5 x year) DIV 4 - C) MOD 7
 
 

 

Easter date algorithms (c) Henk Reints