On 2006-12-09, Clive D.W. Feather challenged, and I couldn't resist: > For something more challenging, try the 8 Bank Holidays in England: > > ... > (8) Second weekday after 24th December.
second weekday after 24th December in Gregorian year( Y ) = Gregorian calendar( Y, December, 26 ) + 2·(floor( D / 5 )) d - (floor( D / 7 )) d where D = day of the week number of Gregorian calendar( Y, December, 25 ) (as in ISO 8601 with values in {1..7} and 1 for Monday) = 1 + ((floor(Y/100) mod 4)·5 + (Y mod 100)·3 - (Y mod 4)·2) mod 7 Sorry for being off-topic. Michael Deckers