Function Day-Of-Week

Part of:

package kmrcl
( day-of-week < year > < month > < day > )

Day of week calculation using Zeller's Congruence.
Input: The year y, month m (1 ≤ m ≤ 12) and day d (1 ≤ d ≤ 31).
Output: n - the day of the week (Sunday = 0, Saturday = 6).