Re: 00:00:00 or 24:00:00

[Joep Beckeringh <joep@xxxxxxxxxxxxxxxxxxx>]

Hm. Shall I mention the leap second, when the time can be 24:59:60? Nah, 
let's not worry about that:-)

Joep Beckeringh

Larry Ducie schreef:
> Hi Peter,
>
> <snip>
> First of all, I'd like to know whether January 1, 2000 00:00:00 is the 
> same as January 1, 2000 24:00:00 (I would think that the latter actually 
> means January 2).
>
> Second, which one is correct?
> </snip>
>
> There are three different answers to this question:
> 1) Using standards agreed for formulating the appropriate representation of
> a designated time.
> In this case ISO 8601 is your guide and would suggest that they are the
> same. Both are correct.
>
> 2) Common sense.
> I would argue that common sense would dictate that January 1, 2000 24:00:00
> should be represented as January 2, 2000 00:00:00., and the latter is
> correct. 
>
> 3) Number theory.
> The 24-hour clock is a base-24, base-60, base-60 number system. As such you
> can never have a number 24:00:00 in it.
>
> The time of day is calculated using the complex number system of base-24,
> base-60, base-60 for HMS (ignoring decimal fractions of a second which are
> base-10 down to infinitely small numbers). At 23:59:59 adding another second
> triggers the standard addition rules to apply, only the bases used differ.
> Thus, the seconds column overflows and is set to 00. The full minute now
> created is carried over to the minutes column. This makes the minute column
> overflow and is set to 00. The full hour now created is carried to the hours
> column. Again, we have to carry over because the hours column is now full.
> Thus we set the hours column to 00 and add 1 to the DAYS column (where did
> that come from???). Unless it is the 30th, or 31st, or 28th/29th of a
> particular month. If it is December we have years to increment!!! :-)
>
> So, I'd say 24:00:00 is NOT 00:00:00, and 00:00:00 is correct, but what I
> say doesn't mattert. Only mathematicians, philosophers and programmers
> actually care, but each for very different reasons.
>
> Cheers
>
> Larry Ducie