Re: Demo: Modelling Cost of Travel Paths Between Towns

"Alan" <alan_at_erols.com> wrote:

>"Ja Lar" <ingen_at_mail.her> wrote in message
>news:419297f4$0$254$edfadb0f_at_dread11.news.tele.dk...
>>
>> "Neo" <neo55592_at_hotmail.com> ...
>>
>> > Upon further reflection, while not taking away from the apparent fact
>> > (I haven't verified it) that ISO-8601 mentions the existance of 24:00,
>> > there is no 24th hr in a day and therefore ISO-8601 is wrong!
>> If you haven't verified it, how can you know that ISO-8610 is wrong?
>> A day certainly has a 24th hour, as a day has 24 hours. The 24th hour
>begins
>> just after 23:00.
>>
>> >The time
>> > in a day can be described by t, where 0:00 <= t < 24:00, and does not
>> > include 24:00.
>> Whow, you are a genius. Thank you for pointing out that t<24:00 does not
>> include 24:00.
>> Now, what about 12:00 AM and 12:00 PM?

>As much as we all like to gang up on Neo, he is actually correct on this
>point. We say a day has 24 hours, but it doesn't. First, we should get our
>terminology correct. We know that astronomically speaking, a day does not
>have 24 hours- it is slightly more- but let's ignore that, as it is not

     Are you referring to the sidereal day? I think that is 23 hours and 56 minutes long.

>important to the problem. Let's also ignore the philosophical discussion
>regarding time that will inevitibly lead us off topic. Let's deal with the
>day-to-day reality of how we deal with time as we know it.

     Day-to-day reality? I find the 2400 notation to be very useful in logging my hours when I am working late.

>According to ISO, we can assign the value 0000 or 2400 to midnight. Let's
>look at another time, say 2 PM, or 1400 . Do we assign two values to 1400?
>No. Nor do we do so for any other time. Why? because each time designation
>represents exactly one point in, well, time- as it must. Now, for the sake
>of simplicity, let's measure time by days, hours, minutes, seconds and
>hundredths of seconds (to avoid extending to the infinite decimal place).
>Day 1 begins at 00:00.00 and ends at 23:59.99. Note that this must mean that
>Day 2 begins at 00:00.00. To conform to the notion that each point in time
>is indicated by one value, there is either no time value of 24:00.00 OR
>there is no time value of 00:00.00. To have both of these is assigning two
>different values to one and only one point in time.

     No, it is assigning two different representations to one value. 2004-11-10 24:00 and 2004-11-11 00:00 are different points of view.

>The ISO standard, though widely adopted (it is a standard, after all) is
>incorrect. The reason midnight gets two values is to make it easier to
>calculate elapsed times, and to clarify what one means when using the term
>"midnight". The problem of calculating elapsed times without the use of 0000
>and 2400 is trivial, so that reason is not a terribly good one. The other
>reason, clarity of meaning, also does not hold. If the ISO midnight standard
>was really a clear expression of a particular point in time, it would be
>easily understood, and insurance contracts would not have to read 12:01 a.m.

     No, it is simpler, but it is not enough for some, so we have ISO-8601.
>No, I do not think we should do away with the standard (it's too late now),
>but let's not pretend it is correct in its represenation of reality.

     It is correct. A day starts at a midnight and ends at the next midnight.

Sincerely,

Gene Wirchenko

Computerese Irregular Verb Conjugation:

     I have preferences.
     You have biases.
     He/She has prejudices.