That was more intended as a rant about things that drive me batty than actual instruction -- I hope it didn't come across as patronizing.
On Thu, Oct 20, 2016 at 12:32 PM, Dmitry Pavlov <dpav...@iaaras.ru> wrote: > 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> > 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-firs >> t.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 >> > >> > -- >> > You received this message because you are subscribed to the Google >> Groups >> > "Racket Users" group. >> > To unsubscribe from this group and stop receiving emails from it, send >> an >> > email to racket-users+unsubscr...@googlegroups.com. >> > For more options, visit https://groups.google.com/d/optout. >> >> -- >> You received this message because you are subscribed to the Google Groups >> "Racket Users" group. >> To unsubscribe from this group and stop receiving emails from it, send an >> email to racket-users+unsubscr...@googlegroups.com. >> For more options, visit https://groups.google.com/d/optout. >> > > > -- You received this message because you are subscribed to the Google Groups "Racket Users" group. To unsubscribe from this group and stop receiving emails from it, send an email to racket-users+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.
