Find which day of the week any date falls on, plus its day-of-year and week number.
Yes — any valid calendar date can be entered, and the day of the week is computed directly from the Gregorian calendar, so past and future dates both work the same way.
It's the ISO-8601 week number (1–53), where week 1 is the week containing the year's first Thursday and weeks run Monday to Sunday — a different convention from a plain "week since Jan 1" count.
Day of Year is the number of days since January 1st of that same year, plus 1 — so January 1st itself is day 1, and December 31st is day 365 (or 366 in a leap year).