How to programmatically determine Good Friday

[Ben]

Hi all,

I understand that Good Friday is different every year based on Full
Moon. Given, that, if I know the Good Friday date falls on one year, is
there a way I can use it as a "seed" and use it to compute all future
years of the date of Good Friday? Is there an algorithm for that?


Thanks,

Ben

 

[XPS350]

Hi all,

I understand that Good Friday is different every year based on Full
Moon.  Given, that, if I know the Good Friday date falls on one year, is
there a way I can use it as a "seed" and use it to compute all future
years of the date of Good Friday?  Is there an algorithm for that?

Thanks,

Ben

As Good Friday is two days before Easter you have your answer when you
know when it is Easter. This function will calculate it for you:


Function Pasen(Jaar As Integer) As Date
Dim A As Byte
Dim B As Byte
Dim C As Byte
Dim D As Byte
Dim E As Byte

A = Jaar Mod 19
B = Int(Jaar / 100)
C = Int((3 * B - 5) / 4)
D = (Int(12 + 11 * A + (8 * B + 13) / 25 - C) Mod 30 + 30) Mod 30

If 11 * D < A + 1 Then
E = 56 - D
Else
E = 57 - D
End If

Pasen = DateValue("01/03/" & Str(Jaar)) + E - 1 - Int(E + (5 * Jaar) /
4 - C) Mod 7

End Function

This one is in Dutch.
Pasen = Easter
Jaar = Year


Groeten,

Peter
http://access.xps350.com

 

[vanderghast]

One matching Catholic & Protestant Easter Sunday (by opposition to Orthodox
Easter, as example): http://aa.usno.navy.mil/faq/docs/easter.php

Other algorithm also exist (such as the one due to Euler) but the one given
in the reference is relatively simple (no if-then-else, no explicit use of
modulo)

Note that it returns Easter Sunday.



Vanderghast, Access MVP

 

[Ben]

Peter, Vanderghast -

Thank you both for your very helpful suggestions. Much appreciated!

Ben