Easter ( myDate )

Show when Easter falls in the calendar year for any given date.

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Mike Duncan
Duncan Creations
http://www.duncancreations.com

Sample input:

Easter ( fields::date )

Sample output:

4/11/2004

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

Let( [ 
   Y = Year(myDate) ;
     C = math.floor(Y/100);
     N = Y - 19*math.floor(Y/19);
     K = math.floor((C - 17)/25);
     I = C - math.floor(C/4) - math.floor((C - K)/3) + 19*N + 15;
     I2 = I - 30*math.floor((I/30));
     I3 = I2 - math.floor(I2/28)*(1 - math.floor(I2/28)*math.floor(29/(I2 + 1))*math.floor((21 - N)/11));
     J = Y + math.floor(Y/4) + I3 + 2 - C + math.floor(C/4);
     J2 = J - 7*math.floor(J/7);
     L = I3 - J2;
     M = 3 + math.floor((L + 40)/44);
     D = L + 28 - 31*math.floor(M/4)
 ] ; 

 Date ( M ; D ; Y )
)

A custom function for figuring when Easter falls in any given year, is based on the algorithm of Oudin (1940). More information can be found about the calculation at <http://tech.irt.org/articles/js052/>. In fact, the custom function used in this example was copied from that page with little modification.

I created an additional custom function:
floor.math (num)
Floor ( num )

In order to copy/paste in code with little modification. This really shows the power of the Let function.

Comments

		Richard Dyce, Dyce & Sons Ltd. Jan 8, 2020
Perhaps you mean 'floor' and not 'math.floor'? Also, for holiday calculations, it's worth pointing out that it's Easter Sunday, so Good Friday and Easter Monday are -2 and + 1 days respectively.

Note: these functions are not guaranteed or supported by BrianDunning.com. Please contact the individual developer with any questions or problems.

Easter ( myDate )

Comments

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