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Common Calendrical Fallacies

yourcalendricalfallacyis.com

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Re: Common Calendrical Fallacies

#21

Post by blahedo »

dahfizz wrote: post #3

This comes off as very "well akchtually"; more snarky than helpful. A great example: >It is normal that the Sept-, Oct-, Nov-, and Dec- months are numbered 9, 10, 11, and 12 >False. This is very weird. They used to be months 7, 8, 9, and 10, but some reform to the Roman calendar back in the day resulted in the creation of January and February, which messed everything up. No software project cares what the calendar lo…

> No software project cares what the calendar looked like during the roman empire. Sure, its quirky that OCTober is month 10 instead of 8. Doesn't affect anything at all.

I take your main point, but its relevance is at least somewhat more recent than the Roman Empire: I've seen engraved statuary that's only a few hundred years old, in France, that used abbreviations like "VIIbre" for "septembre". Still not of direct interest to a software project probably but in recent enough history that you might interact with it in scanned archive data.

Re: Common Calendrical Fallacies

#22

Post by II2II »

dahfizz wrote: post #3

This comes off as very "well akchtually"; more snarky than helpful. A great example: >It is normal that the Sept-, Oct-, Nov-, and Dec- months are numbered 9, 10, 11, and 12 >False. This is very weird. They used to be months 7, 8, 9, and 10, but some reform to the Roman calendar back in the day resulted in the creation of January and February, which messed everything up. No software project cares what the calendar lo…

> This comes off as very "well akchtually"; more snarky than helpful.

Agreed. It would have been much more useful if the article was upfront about its intent, rather than stating it in the last paragraph along with categorizing the potential pitfalls in writing such code (e.g. time, international, cultural, historic, etc.).

The categorizing is important since most, if not all, of the cases will be relevant in some circumstances and not in others. A day planner may need to consider international variation, you may need to consider leap seconds in log files, while historic and cultural variations is useful for some planetarium software.

Re: Common Calendrical Fallacies

#23

Post by wbl »

noneeeed wrote: post #5
dahfizz wrote: post #3

This comes off as very "well akchtually"; more snarky than helpful. A great example: >It is normal that the Sept-, Oct-, Nov-, and Dec- months are numbered 9, 10, 11, and 12 >False. This is very weird. They used to be months 7, 8, 9, and 10, but some reform to the Roman calendar back in the day resulted in the creation of January and February, which messed everything up. No software project cares what the calendar lo…

You say "No software project cares"... but I'm sure there are pieces of software out there used for dealing with historical/archeological data and have to deal with stuff like this :) I would not want to have to work on it. Archeologists must spend a lot of time reconciling different calendars and all the changes that have happened over the years. And yeah, if I go the rest of my career never having to work with cale…

And astronomers. A lot of work goes into matching up eclipses to pin down exact dates and then reconstructing regal years. Even with this there is some uncertainty in the timeline of the Assyrian empire.

Re: Common Calendrical Fallacies

#24

Post by throw0101a »

dahfizz wrote: post #3

This comes off as very "well akchtually"; more snarky than helpful. A great example: >It is normal that the Sept-, Oct-, Nov-, and Dec- months are numbered 9, 10, 11, and 12 >False. This is very weird. They used to be months 7, 8, 9, and 10, but some reform to the Roman calendar back in the day resulted in the creation of January and February, which messed everything up. No software project cares what the calendar lo…

> No software project cares what the calendar looked like during the roman empire. Sure, its quirky that OCTober is month 10 instead of 8. Doesn't affect anything at all.

Unless you're doing astronomy:

* https://stellarium.org/doc/0.21/classJulianCalendar.html

* https://en.wikipedia.org/wiki/Julian_year_(astronomy)

* https://en.wikipedia.org/wiki/Julian_day

* https://squarewidget.com/julian-day/

> There is also a Julian date commonly used in astronomy, which is a serial date system starting on January 1, 4713 B.C.E.

* https://support.microsoft.com/en-us/office/insert-julian-dat...

Re: Common Calendrical Fallacies

#25

Post by krallja »

clusterfish wrote: post #17
TehShrike wrote: post #10

I wish there was a version of this that only contained examples relevant to e.g. the Gregorian calendar, or even within the subset of the Gregorian calendar specified within POSIX. I get whiplash going back and forth between "relevant thing I need to care about" and "obviously irrelevant" in this list

I'm not sure if this is the original, but here: https://infiniteundo.com/post/25326999628/falsehoods-program...

https://www.kalzumeus.com/2010/06/17/falsehoods-programmers-... is two years older

Re: Common Calendrical Fallacies

#26

Post by krallja »

shazar wrote: post #14

> So if you’re writing code and are trying to use the time 00:00:00 to represent “no time”, you will be wrong in these countries. Well, obviously using `00:00:00` as no-time is a terrible idea, but isn't that statement just wrong? If it's used to represent no-time, it would actually have a very low chance of doing what it's supposed to do in those countries, but fail all the time at all other time zones.

FogBugz calculated “daily task” times based on the site’s time zone. If this was set to a timeline like Chile, the daily tasks processor would crash in a loop, until the next day, which did have a 00:00:00. This caused horrible alerts to plague the systems engineer on call.

Re: Common Calendrical Fallacies

#27

Post by Fnoord »

> The current year is 2020

False, the current year according to the Grogorian calendar is 2022.

Disappointing an article as pedantic as this one fails itself. (Yes, I am aware it was likely written in 2020. That is the point: it assumed the reader read it in 2020.)

Re: Common Calendrical Fallacies

#28

Post by cutler »

He omitted a really big one - the beginning of spring. Most people are convinced spring begins at the equinox around 20th March but are also quite happy to talk about Mid-Summer's Day at the summer solstice around 20th June. Sorry, ya can't have it both ways. If the summer solstice is mid-summer then the spring equinox 3 months earlier must be mid-spring. It all boils down to how seasons are defined and here I find even astronomers can be really lazy in their thinking. Seasons are defined by the intersection of the Sun's apparent path and the equator so equinoxes are where the Sun's path crosses the equator and the solstices (Sun standing still) are the maxima and minima of the Sun's path. However, a maxima/minima can only be the mid-point of a season since points either side of a maxima/minima are equal in terms of the relative amounts of daylight. Seasons are defined by the amount of daylight, hence the summer solstice in the northern hemisphere, around 20th June, is the mid-point of summer when we celebrate "Mid-Summer's Day". All else follows from this and spring begins around 5th February in the northern hemisphere.

Re: Common Calendrical Fallacies

#29

Post by charcircuit »

cutler wrote: post #28

He omitted a really big one - the beginning of spring. Most people are convinced spring begins at the equinox around 20th March but are also quite happy to talk about Mid-Summer's Day at the summer solstice around 20th June. Sorry, ya can't have it both ways. If the summer solstice is mid-summer then the spring equinox 3 months earlier must be mid-spring. It all boils down to how seasons are defined and here I find e…

I thought summer started on the summer solstice. I've never heard it called "midsummer's day"

Spring: March April May

Summer: June July August

Fall: September October Novmeber

Winter: December January February

Re: Common Calendrical Fallacies

#30

Post by cutler »

charcircuit wrote: post #29
cutler wrote: post #28

He omitted a really big one - the beginning of spring. Most people are convinced spring begins at the equinox around 20th March but are also quite happy to talk about Mid-Summer's Day at the summer solstice around 20th June. Sorry, ya can't have it both ways. If the summer solstice is mid-summer then the spring equinox 3 months earlier must be mid-spring. It all boils down to how seasons are defined and here I find e…

I thought summer started on the summer solstice. I've never heard it called "midsummer's day" Spring: March April May Summer: June July August Fall: September October Novmeber Winter: December January February

That's exactly the fallacy I'm referring to. Mid-Summer's day (https://en.wikipedia.org/wiki/Midsummer) is a calendrical festival observed in many cultures around 24th June close to the summer solstice. How do you define a season? What single factor determines how a season is measured? It's the relative amount of daylight. The summer solstice is the longest day.
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