Calculation formula of perpetual calendar

What is a certain day in history? What day is the future? There are many formulas about this problem (two general formulas and some subsection formulas), among which Zeiler formula is the most famous.

That is, w = y+[y/4]+[c/4]-2c+[26 (m+1)1+d-1.

The symbols in the formula have the following meanings: w: week; C: Century-1; Y: year (two digits); M: Month (m is greater than or equal to 3, but less than or equal to 14, that is, in Chuller's formula, 1 and February in one year should be regarded as 13 and 14 in the previous year, for example, 1 in 2003 should be regarded as 2002. D: day; 【】 stands for rounding, that is, only the integer part is taken. C is the number of centuries minus one, Y is the last two digits of the year, M is the month, and D is the number of days.

65438+ 10 and February should be calculated according to the previous year's 65438+March and 65438+April, when C and Y are calculated according to the previous year. )

The calculated w is divided by 7, and the remainder is the day of the week. If the remainder is 0, it is Sunday.

Take 65438+20491October1(100th National Day) as an example, the process is as follows:

Zeiler formula: w = y+[y/4]+[c/4]-2c+[26 (m+1)1+d-1.

=49+[49/4]+[20/4]-2×20+[26× ( 10+ 1)/ 10]+ 1- 1

=49+[ 12.25]+5-40+[28.6]

=49+ 12+5-40+28

=54 (divided by 7 and 5)

That is, June 2049 10 (the100th national day) is Friday.

When is your birthday (when you were born, this year, next year)? Might as well try.

However, the above formula only applies to the situation after 158210/0/015 (at that time, the Pope changed julian calendar made by Julius Caesar to the Gregorian calendar, which is the Gregorian calendar used today).