If $Year = ""
	$Year = @YEAR
EndIf

; Is the specified year valid?
; Check if number and if within range
If VarType($Year) = 1 OR VarType($Year) <> 3 OR $Year < 1752 OR $Year > 3000
	GOTO Syntax
EndIf

; Calculate Easter Day using the instructions found at
; Simon Kershaw's "KEEPING THE FEAST"
; http://www.oremus.org/liturgy/etc/ktf/app/easter.html
$G  = Mod( $Year, 19 ) + 1
$S  = (( $Year - 1600 ) / 100 ) - (( $Year - 1600 ) / 400 )
$L  = ((( $Year - 1400 ) / 100 ) * 8 ) / 25
$P1 = Mod(( 30003 - 11 * $G + $S - $L ), 30)
Select
	Case $P1 = 28 AND $G > 11
		$P = 28
	Case $P1 = 29
		$P = 28
	Case 1
		$P = $P1
EndSelect
$D  = Mod(( $Year + ( $Year / 4 ) - ( $Year / 100 ) + ( $Year / 400 )), 7 )
$D1 = Mod(( 8 - $D ), 7 )
$P2 = Mod(( 70003 + $P ), 7 )
$X  = Mod(( 70004 - $D - $P ), 7 ) + 1
$E  = $P + $X
If $E < 11
	$ED = $E + 21
	$EM = "March"
Else
	$ED = $E - 10
	$EM = "April"
EndIf
Select
	Case $Year < @YEAR
		$IS = "was"
	Case $Year = @YEAR
		$IS = "is"
	Case 1
		$IS = "will be"
EndSelect

; Display the result
? "In $Year Easter Day $IS $EM $ED"
?

; MOD function divides $Op1 by $Op2 and returns the remainder
Function Mod($Op1,$Op2)
	$Mod = $Op1 - $Op2 * ( $Op1 / $Op2 )
EndFunction

; End of main program
Exit 0


:Syntax
? "Easter.kix,  Version 1.00"
? "Calculate the date of Easter Day for the specified year."
?
? "Usage:  KIX32  EASTER.KIX  [ $$YEAR=year ]"
?
? "Where:  year should be within the range of 1752 through 3000"
?
? "Written by Rob van der Woude"
? "http://www.robvanderwoude.com"
?
? "Based on the instructions found at"
? "Simon Kershaw's " + Chr(34) + "KEEPING THE FEAST" + Chr(34)
? "http://www.oremus.org/liturgy/etc/ktf/app/easter.html"
?
Exit 1