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Australia/Lord_Howe is the weirdest timezone

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Re: Australia/Lord_Howe is the weirdest timezone

#111

Post by Kwpolska »

grotorea wrote: post #98
yokoprime wrote: post #86

Earlier quoted context omitted.

Without getting deep into politics I don't understand why they would prioritize spending effort on DST at all, seems like there are plenty of other concerns.

I don't see why announcing DST would be a big effort. And it saves on electricity costs.

Even if DST did save something (it does not), it becomes a problem when your timekeeping is done by computers. My computers know I live in Poland (Europe/Warsaw), and they know the DST rules. I can trust the time on my computers’ clock matches the official time the government recognizes.

In Palestine, this depends on my OS vendor managing to update the tz database in the short window before the official announcement and the decision coming into force. (I believe the tz database makes some assumptions based on past performance, but the government can change their mind any year.) If my OS does not update, I need to change my time zone manually to something that has the right UTC offset, and then I need to manually change back in the autumn, and I can never be 100% sure if any given computer shows the official time.

Re: Australia/Lord_Howe is the weirdest timezone

#112

Post by seoulbigchris »

alexjplant wrote: post #40

Earlier this year I had to write a function to find the current local time given a US address. The naive way to do so would be via a static mapping of state to time zone but there are a few edge cases that preclude doing this; in the interest of cost and speed relative to this specific application I spent a few dollars on a CSV that maps every US ZIP code to UTC offset and whether DST is followed (among other data).…

As a young engineer right out of university back in 1985, one of my early tasks involved merging together a bunch of telemetry data provided on mag tapes recorded at different radar sites (in the USA). One or two of the systems time stamped their data in local time, and all the others used UTC. I remember buying one of those old Farmers' Almanacs in order to make an algorithm to account for DST. When I read the rules, I threw up my arms in despair.

The almanac gave nominal rules for the transitions. But there was a footnote explaining that these transitions had and will continue to be adjusted year to year due to Congressional intervention. I showed this to my boss and said, "If I could write an algorithm that predicted future votes of Congress, I would be a billionaire and could quit this engineering job."

I think in the end I coded the algorithm with the recent known transitions, and the nominal rules for future ones. What else could you do (this was before everyone was networked, and the code ran on standalone computers like a VAX).

I also learned that task of merging three sources of tracking data, each with its own validity and measurement degradation status, was an absolute nightmare. But still easier than predicting future actions of Congress.

Re: Australia/Lord_Howe is the weirdest timezone

#113

Post by marcthe12 »

hypeatei wrote: post #77
vander_elst wrote: post #63

I still hope that someday the whole world will run on UTC0 and there is no more time zones madness. I know the day will likely never come but I like to keep dreaming.

I'd rather timezones be split based on actual logic rather than politics and eliminate things like daylight savings. It's insane to me that China has one timezone because they felt like it. People must sleep terribly in certain regions.

Yep. And the logic can be made very easy. Outside polar regions or outer space, timezone could simply be the longitude/15 degrees rounded to a constant fraction. This is not perfect as cities maybe in 2 time zones but this basically a really good approximation.

Re: Australia/Lord_Howe is the weirdest timezone

#114

Post by roryirvine »

rubenv wrote: post #88
tankenmate wrote: post #58

"Running cron jobs on an hourly basis doesn’t in practice have very weird interactions with DST" Of course every sane person runs their default system clock on UTC and lets users pick their own local time. That way cron always does the "right thing"(TM).

That's true if you need to clean up temporary files every night or make a backup. But what if your cronjob has an effect in the physical world, locally? E.g. open the parking gates every morning. The world is inherently messy :-)

That sort of thing would be best handled by your own user's crontab, so would naturally inherit that user's TZ.

If you must run it as root, you can specify a CRON_TZ variable on a per-file basis, which will override the default.

Re: Australia/Lord_Howe is the weirdest timezone

#115

Post by throw0101a »

arethuza wrote: post #82
marginalia_nu wrote: post #66

Earlier quoted context omitted.

That's very similar to how the romans conceived of time. Wonder if it's an old relic from when north africa was a bunch of provinces. https://en.wikipedia.org/wiki/Roman_timekeeping

"An hour was defined as one twelfth of the daytime" That must have been fun for the Romans here in Scotland - an hour would be roughly two and a half time as long in winter as in summer!

> That must have been fun for the Romans here in Scotland - an hour would be roughly two and a half time as long in winter as in summer!

Mechanical clocks in Japan were designed to handle those situations:

> Adapting the European clock designs to the needs of Japanese traditional timekeeping presented a challenge to Japanese clockmakers. Japanese traditional timekeeping practices required the use of unequal time units: six daytime units from local sunrise to local sunset, and six night-time units from sunset to sunrise.

* https://en.wikipedia.org/wiki/Japanese_clock#Temporal_hours

Re: Australia/Lord_Howe is the weirdest timezone

#116

Post by TheNewsIsHere »

seoulbigchris wrote: post #112
alexjplant wrote: post #40

Earlier this year I had to write a function to find the current local time given a US address. The naive way to do so would be via a static mapping of state to time zone but there are a few edge cases that preclude doing this; in the interest of cost and speed relative to this specific application I spent a few dollars on a CSV that maps every US ZIP code to UTC offset and whether DST is followed (among other data).…

As a young engineer right out of university back in 1985, one of my early tasks involved merging together a bunch of telemetry data provided on mag tapes recorded at different radar sites (in the USA). One or two of the systems time stamped their data in local time, and all the others used UTC. I remember buying one of those old Farmers' Almanacs in order to make an algorithm to account for DST. When I read the rules…

This is a fantastic story, well and amusingly told.

Re: Australia/Lord_Howe is the weirdest timezone

#117

Post by tankenmate »

rubenv wrote: post #88
tankenmate wrote: post #58

"Running cron jobs on an hourly basis doesn’t in practice have very weird interactions with DST" Of course every sane person runs their default system clock on UTC and lets users pick their own local time. That way cron always does the "right thing"(TM).

That's true if you need to clean up temporary files every night or make a backup. But what if your cronjob has an effect in the physical world, locally? E.g. open the parking gates every morning. The world is inherently messy :-)

Well assuming that the gates don't move timezones. But obviously jobs that need to run for a given timezone should be configured to run in that timezone.

Re: Australia/Lord_Howe is the weirdest timezone

#118

Post by hhdhdbdb »

fouronnes3 wrote: post #103
dalmo3 wrote: post #61

Earlier quoted context omitted.

You forgot that UTC (or timekeeping in general) itself is a diff.

Oh that's a great point! We have achieved diff^5 at last! Now that I think of it, we could even stretch it one more level. In practice UTC is "realized" as a "best of" diff to atomic clocks in labs around the world, which are themselves diff against a fixed time point, as you pointed out. So that realization technically changes when the official UTC bulletin[1] is published by BIPM. So diff^6! [1] https://www.bipm.or…

Can we bring relativity in for another diff :)

Re: Australia/Lord_Howe is the weirdest timezone

#119

Post by pbmonster »

arethuza wrote: post #82
marginalia_nu wrote: post #66

Earlier quoted context omitted.

That's very similar to how the romans conceived of time. Wonder if it's an old relic from when north africa was a bunch of provinces. https://en.wikipedia.org/wiki/Roman_timekeeping

"An hour was defined as one twelfth of the daytime" That must have been fun for the Romans here in Scotland - an hour would be roughly two and a half time as long in winter as in summer!

Much less of an issue without clocks.

Look where the sun is, remember where it is at sunrise/-set (much easier if you're outside every day) and then mentally divide the sky into segments and just ballpark it.

Re: Australia/Lord_Howe is the weirdest timezone

#120

Post by hhdhdbdb »

hprotagonist wrote: post #96
guidedlight wrote: post #18

Nah, the weirdest time zone is Africa/Addis_Ababa, which nobody in Ethiopia follows. Instead the locals offset the time by 6 hours. So the AM cycle starts at dawn (i.e. 6am), and the PM cycle starts at dusk (i.e. 6pm). https://en.wikipedia.org/wiki/Time_in_Ethiopia

Ethiopian time keeping is peculiar all over. https://en.wikipedia.org/wiki/Ethiopian_calendar The Ethiopian calendar has twelve months, all thirty days long, and five or six epagomenal days, which form a thirteenth month.

That no odder than Gregorian
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