Computing Day of the Week

[Mike Tietel]

I know there exists an algorithm to compute the day of the week,
given the month, day and year.  For example, what day of the week
is September 13, 1998?

Does anyone know where I can find the algorithm, or alternatively,
where I can find its "C" implementation???

Thanks in advance...
-- 
Mike Tietel
Northern Telecom, Inc.       (612) 932-8017
9701 Data Park, S-100        mike at ntmtka.mn.org
Minnetonka, MN 55343         uunet!rosevax!ntmtka!mike