David,
Yes, I deal with most of this at work, except daylight savings.
(Timestamps in astronomical observations are predominantly in UTC or
rarely TT/TDB, I never saw local time.)
Best regards,
Dmitry
On 10/20/2016 07:26 PM, David Storrs wrote:
Also be aware that once you start getting into date math you need to
deal with:
*) Minutes that might have 61 seconds in them. Yes, hh:mm:60 is a
real time.
*) Hours that don't exist.
*) Hours that happen twice in the same day.
*) Februaries that have 28 or 29 days on a weird schedule. (If the
year is divisible by 4, unless it's divisible by 100, unless it's
divisible by 400.)
*) Two weeks that didn't exist due to calendars switching over.
*) The modern calendar being adopted at different points in different
countries. Greece didn't start using it until 1923.
On Thu, Oct 20, 2016 at 12:13 PM, Matthew Flatt <mfl...@cs.utah.edu
<mailto:mfl...@cs.utah.edu>> wrote:
Did you timezone use daylight saving in 1996?
In U.S. timezones, March (it used to be April) has a 1-hour hole
due to
the switch to daylight saving time, where the clock skips forward from
1:59am to 3:00am. For example, 2:47:59am on March 13, 2016 really did
not exist in my timezone.
At Thu, 20 Oct 2016 19:05:38 +0300, Dmitry Pavlov wrote:
> Hello,
>
> The surprise of the day for me is date->seconds
> rejecting a particular time on a particular date.
>
> (date->seconds (date 59 47 2 31 3 1996 0 0 #f 0))
>
> This should be 1996, March 31, 02:47:59 am, correct?
>
>
> It reports the following error:
>
> find-seconds: non-existent date
> wanted: (59 47 2 31 3 1996)
> nearest below: 828226799 is (59 59 1 31 3 1996)
> nearest above: 828226800 is (0 0 3 31 3 1996)
> context...:
> /opt/racket/collects/racket/date.rkt:234:0: date->seconds
>
/opt/racket/collects/racket/contract/private/arrow-val-first.rkt:306:25
> /opt/racket/collects/racket/private/misc.rkt:88:7
>
> From the message, I can suppose that it misses a whole hour inside.
>
> What can be done?
>
> This is Racket 6.6 on Linux.
>
>
> Best regards,
>
> Dmitry
>
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