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Easterday ( Date )

Calculates the date for any easterday according to Gauss formula.

  Average rating: 4.5 (29 votes) Log in to vote

Johan Söderberg - Show more from this author Distingo Scenproduktion http://www.distingo.nu

  Function definition: (Copy & paste into FileMaker's Edit Custom Function window)

Date(If(Mod(((19*Mod(four_digit_yearfield; 19)) + 24);30)+Mod(((2*Mod(four_digit_yearfield; 4)) + (4*Mod(four_digit_yearfield; 7))+(6*Mod(((19*Mod(four_digit_yearfield; 19)) + 24);30))+5); 7) < 10; "03"; "04"); If(If(Mod(((19*Mod(four_digit_yearfield; 19)) + 24);30) +Mod(((2*Mod(four_digit_yearfield; 4)) + (4*Mod(four_digit_yearfield; 7))+(6*Mod(((19*Mod(four_digit_yearfield; 19)) + 24);30))+5); 7) ≥10 ; Mod(((19*Mod(four_digit_yearfield; 19)) + 24);30)+ Mod(((2*Mod(four_digit_yearfield; 4)) + (4*Mod(four_digit_yearfield; 7))+(6*Mod(((19*Mod(four_digit_yearfield; 19)) + 24);30))+5); 7) - 9;Mod(((19*Mod(four_digit_yearfield; 19)) + 24);30)+Mod(((2*Mod(four_digit_yearfield; 4)) + (4*Mod(four_digit_yearfield; 7))+(6*Mod(((19*Mod(four_digit_yearfield; 19)) + 24);30))+5); 7)+22) > 9; If(Mod(((19*Mod(four_digit_yearfield; 19)) + 24);30) + Mod(((2*Mod(four_digit_yearfield; 4)) + (4*Mod(four_digit_yearfield; 7))+(6*Mod(((19*Mod(four_digit_yearfield; 19)) + 24);30))+5); 7) ≥10 ;Mod(((19*Mod(four_digit_yearfield; 19)) + 24);30) + Mod(((2*Mod(four_digit_yearfield; 4)) + (4*Mod(four_digit_yearfield; 7))+(6*Mod(((19*Mod(four_digit_yearfield; 19)) + 24);30))+5); 7) - 9; Mod(((19*Mod(four_digit_yearfield; 19)) + 24);30)+Mod(((2*Mod(four_digit_yearfield; 4)) + (4*Mod(four_digit_yearfield; 7))+(6*Mod(((19*Mod(four_digit_yearfield; 19)) + 24);30))+5); 7)+22); "0"&If(Mod(((19*Mod(four_digit_yearfield; 19)) + 24);30) +Mod(((2*Mod(four_digit_yearfield; 4)) + (4*Mod(four_digit_yearfield; 7))+(6*Mod(((19*Mod(four_digit_yearfield; 19)) + 24);30))+5); 7) ≥10 ;Mod(((19*Mod(four_digit_yearfield; 19)) + 24);30) + Mod(((2*Mod(four_digit_yearfield; 4)) + (4*Mod(four_digit_yearfield; 7))+(6*Mod(((19*Mod(four_digit_yearfield; 19)) + 24);30))+5); 7) - 9;Mod(((19*Mod(four_digit_yearfield; 19)) + 24);30)+Mod(((2*Mod(four_digit_yearfield; 4)) + (4*Mod(four_digit_yearfield; 7))+(6*Mod(((19*Mod(four_digit_yearfield; 19)) + 24);30))+5); 7)+22)); four_digit_yearfield) Click to copy

This is a solution to calculate when Easterday will show up in the calendar year.

I made this many years ago when I was trying to develop Matt Petrovskys brilliant little calendar into something more useful. I wanted the calendar to mark all Swedish holidays and found that easterday was the only one difficult to calculate and that another three holidays were dependendant on this highly variable and seemingly unpredictable date.

With this formula all you need is a numeric field with a year in it. In the function that field is refered to as "four_digit_yearfield"

More info on Gauss formula:
http://mathforum.org/library/drmath/view/52575.html

 

Comments

		comment, VR Aug 7, 2011
http://www.wheniseastersunday.com/year/1981/ Also 1954, 2049, 2076 and almost all years after 2099 and before 1900.

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