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Calendar FAQ

The Frequently Asked Questions about Calendars document is available here:

http://www.tondering.dk/claus/calendar.html

 
Calendar Algorithms

The Calendar FAQ includes a number of formulas for calculating various calendar values.

I have written a very simple implementation of these formulas in the C language. Rather than providing the most efficient code, the implementation intentionally follows the formulas very closely.

The code can be downloaded as a ZIP file

 
30 February

As described the Calendar FAQ, February had 30 days in Sweden in 1712.

The picture below shows two pages from a Swedish almanac from 1712.

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31 February

Although a 30 February has indeed occurred in history, what about 31 February?

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Did He Die Before He Was Born?

The photo below shows a tombstone located in the floor of the North Choir Aisle of Salisbury Cathedral in England. It illustrates how the new year hasn't always started on 1 January.

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A Very Old Date

You rarely get to see a 3-digit year in actual use. The photo below shows the date in a document signed by the Holy Roman Emperor Charles III (a.k.a. Charles the Fat) on 2 April 883.

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Translations

Translations of older versions of the Calendar FAQ are available in these languages: