Whilst exploring Greenwich, we found out why!
Algorithm
Read below, or click here for a more understandable explanation.
An algorithm to find the date of Easter which is valid from 1900 to 2099 has been derived by Carter.
Calculate D="'225'" - 11(Y MOD 19).
If D is greater than 50 then subtract multiples of 30 until the resulting new value of D is less than 51.
If D is greater than 48 subtract 1 from it.
Calculate E="'(Y" +' [Y/4] + D + 1) MOD 7. (NB Integer part of [Y/4])
Calculate Q="'D +'" 7 - E.
If Q is less than 32 then Easter is in March. If Q is greater than 31 then Q - 31 is its date in April.
For example, for 1998:
D = 225 - 11*(1998 MOD 19) = 225 - 11*3 = 192
D is greater than 50, therefore:
D = (192 - 5*30) = 42
E = (1998 + [1998/4] + 42 + 1) MOD 7="'2540'" MOD 7="'6'"
Q = 42 + 7 - 6="'43'"
Easter 1998="'43" -' 31="'12" April'
1 comment:
Oh, well, that makes it SO much easier. No waiting around with bated breath for the next year's calendars to come out. Now I have a simple and quick method to figure it out for myself. With the help of a scientific calendar and two or three sheets of paper, and perhaps some prompting from Ian. What a relief. ;-p
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