Year(s) Month(s) Day(s) between 2 dates

[Dieter]

(10-23-2015 03:42 PM)Didier Lachieze Wrote:  Gérard has brought me an interesting question: with a start date of 23 Feb. 1951 and an end date of 5 Sept. 1999 the program from Dieter with ΔDAYS (as well as my optimized versions) returns 48 years, 6 months and 13 days, however Gerard’s own program as well as another one he has on the 50g (not written by him) returns 48 years, 6 months and 10 days.

The difference in the number of days comes from the way the interval duration is calculated:
If you add 48 years and 6 months to the start date you get 23 Aug. 1999, 13 days before 5 Sept. 1999.
However if you first add 10 days to the start date you get 5 mar. 1951 which is 48 years and 6 months before 5 Sept. 1999.

Yes – this point has already been discussed in March in the original thread on this topic (see also post #12). There simply is no unique "correct" answer in years, months and days because the result depends on the way you do the calculation.

(10-23-2015 03:42 PM)Didier Lachieze Wrote:  Does anybody knows if there is a standard rule for calculating such date intervals and if one of the two possible answers should be considered the right one?

I think we can safely assume that "the standard" is Wolfram Alpha. ;-)

Dieter