Today is Thursday, 2018/02/22.

• Why is the 1st day Day 0? The discrepancy is due to treating the dates as ordinal (1st, 2nd, 3rd, ...) and cardinal (0, 1, 2) numbers. It is equivalent to a person being age 0 during the first year of his life.

Date 1: Year :  Month :  Day : 
Date 2: Year :  Month :  Day : 

1974/07/24
Wednesday
⇒ ⇒ ⇒ 2018/02/22
Thursday
Day 0
1st Day
⇒ ⇒ ⇒ Day 15,919
15,920th Day

 

Date : Year :  Month :  Day : 
N :   

2018-02-22
Thursday
⇒ ⇒ ⇒ 2020-11-17
Tuesday
2020-11-18
Wednesday
Day 0
1st Day
⇒ ⇒ ⇒ Day 999
1,000th Day
Day 1,000
1,001st Day

 

• This program is written in R (r-project.org).
    The "brew" package is used to integrate R and HTML.