Formula for EasterDate: 06/12/99 at 10:49:49 From: john Subject: Formula for Easter Hi! I was wondering if you have any formula for solving this Easter holiday question: If you have the year, how would you figure out the month and the day on which Easter occurs that year? Thank You for your time. Date: 06/12/99 at 12:15:04 From: Doctor Anthony Subject: Re: Formula for Easter Gauss derived a formula to find the day (D) and month (M) on which Easter day falls given the year (T) Below is shown the formula and its application to the year 1999 If k = Integer part of [T/100] k = Int[1999/100] = 19 a = T (mod 19) a = 1999 (mod 19) = 4 b = T (mod 4) b = 1999 (mod 4) = 3 c = T (mod 7) c = 1999 (mod 7) = 4 q = Integer part of [k/4] q = Int[19/4] = 4 p = Integer part of [(13+8k)/25] p = Int[165/25] = 6 m = (15-p+k-q) (mod 30) m = 24 (mod 30) = 24 d = (19a + m) (mod 30) d = 100 (mod 30) = 10 n = (4+k-q) (mod 7) n = 19 (mod 7) = 5 e = (2b+4c+6d+n) (mod(7) e = 87 (mod 7) = 3 If d+e <= 9 then D = 22+d+e and M = 3 d+e = 10+3 = 13 If d = 29 and e = 6 then D = 19 and M = 4 (not applicable here) If d = 28 and e = 6 and a > 10 then D = 18 and M = 4 (not applicable here) Otherwise D = d+e-9 and M = 4 D = 13-9 = 4, M=4 So Easter day in the year 1999 was on April 4th. - Doctor Anthony, The Math Forum http://mathforum.org/dr.math/ |
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