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Excel incorrectly assumes that the year 1900 is a leap year

In other "incorrect calendars" bugs, there's the Rockchip RK808 RTC, where the engineers thought that November had 31 days, needing a Linux kernel patch to this day that translates between Gregorian and Rockchip calendars (which are gradually diverging over time).

Also one of my favourite kernel patch messages: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/lin....

4 hours agonippoo

To be fair, that's nowhere near as daft as september, october, november, december. Latin for seven, eight, nine, and ten is: septem, octem, novem, decem. Those are the nineth, 10th, 11th and 12th months.

Edit: Whoops, correct eng -> latin nums

4 hours agogerdesj

You may know this but originally they were 'correct' because the start of the year was March.

3 hours agoemmelaich

Which wouldn't be that weird, except that the earliest Roman calendar started in March and ended in December, having only 10 months!

The Romans were of course well aware that this left a gap of about two months between the end of one year in December, and the beginning of the next year in March. But they just didn't bother counting this period as part of the calendar year. Presumably because there was no agricultural reason to need accurate dates during winter.

3 hours agoteraflop

Numa did try to name and consolidate the winter months, but it wasn't very popular.

The months were for productive seasons, winter for everything else.

2 hours agoshakna

No? How is it octem and not octo? Does the flat bar accent do something?

>The Latin word for "eight" is octō. [0]

[0] asked google

2 hours agocaminante

And indeclinable.

an hour agojasomill

I was developing an interface to read a .xslx file to import a table within a Qt/C++ program, and this detailed showed up in my conversions to Unix time. It turns out Claude was amazing and brought up this issue as soon as Excel was mentioned, but terrible at actually fixing up the calculations.

I'd prefer using a .csv with dates already converted to Unix time, but no luck convincing the other people involved.

4 minutes agojwrallie

I learned about this from my Macintosh back in The Day™, when a dead Parameter RAM battery would reset the system date to January 1st, 1904 at every boot:

- https://spinsidemacintosh.neocities.org/im202#im033-001

> “The date and time setting is also copied at system startup from the clock chip into its own low-memory location. It’s stored as a number of seconds since midnight, January 1, 1904, and is updated every second. The maximum value, $FFFFFFFF, corresponds to 6:28:15 AM, February 6, 2040; after that, it wraps around to midnight, January 1, 1904.”

- https://archive.org/details/mac_Macworld_Mac_Secrets_5th_Edi...

- http://preserve.mactech.com/articles/develop/issue_26/minow....

- https://preterhuman.net/macstuff/qa/ops/ops23.html

an hour agoLammy

> Applies to: Microsoft Excel for Mac 2011, Excel for Microsoft 365 for Mac, Microsoft Office Excel 2003, Microsoft Office Excel 2007, Excel 2010, Excel 2013, Excel 2016

4 hours agodarknavi

This will never stop as it would require either the reference date to be changed or fir all dates in all saved spreadsheets to be off by one.

4 hours agoetothepii

Or... A version number that tells excel which convention to use?

I suppose that would make copy and pasting formulas between spreadsheets very mildly error prone though, so it probably won't happen.

2 hours agogpm

What about Microsoft 366?

3 hours agoparenthesis

Although it is technically possible to correct this behavior so that current versions of Microsoft Copilot 366 is a leap year, the disadvantages of doing so outweigh the advantages.

3 hours agoa012

> If this behavior were to be corrected, many problems would arise, including: > Almost all dates in current Microsoft Excel worksheets and other documents would be decreased by one day.

Unless your fix adds a day to make them stay the same??

And these silly "compatibility" excuses are begins bugs affecting more and more unsuspecting users like that gene import conversion bug affecting a quarter of all published gene research papers.

an hour agoeviks

The story behind this is one of the best backward compatibility parables in computing. Lotus 1-2-3 originally made the mistake, and when Microsoft built Excel they deliberately reproduced it so that Lotus spreadsheets would import with correct dates. Fixing it now would silently shift every date serial number in every saved spreadsheet by one day -- and you can't safely make that change because you don't know how many downstream systems depend on those serial numbers being exactly what they are.

It's the same pattern that keeps x86 booting in real mode, keeps JavaScript's == doing type coercion, and keeps POSIX using null-terminated strings. Once a bug lives in enough production systems, it stops being a bug and becomes an interface contract. The cost of correctness exceeds the cost of the error, so the error becomes the standard.

an hour agostainlu
[deleted]
4 hours ago

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