A perpetual function for finding day of week.
There is also a monthly calendar table generator.
Functions are for gregorian calendar, which world use today.
Weekday shall be wrong historically for dates before 15 October 1582.
It shall be correct for gregorian calendar however not for julian.
Because before that date julian calendar was being used.

Regards

dayofweek_calendar.sm (23 KiB) downloaded 89 time(s).
dayofweek_calendar.pdf (223 KiB) downloaded 84 time(s).