Hello. Do you know the Fairfield's congruence?
Firstly, if m is 1 or 2, compute y=y-1,m=m+12. Then calculating this formula, you can get the number of days between an arbitrary date and 01/01/0001.
In Japan, this formula is known as the Fairfield's congruence, but I have never seen the foreign people who have been talking about it.
It is mentioned in only the Japanese Wikipedia's page of "Zeller's congruence" below. http://ja.wikipedia.org/wiki/%E3%83%84%E3%82%A7%E3%83%A9%E3%83%BC%E3%81%AE%E5%85%AC%E5%BC%8F
Do you know who Fairfield is? I don't know.
Do you know a famous formula like the Fairfield's congruence?