[Remind-Fans] Calendar systems (was Re: Determining Ramadan & Eid?)

[Dianne Skoll]

On Wed, 22 Mar 2023 13:53:03 -0400
hymie! via Remind-fans <remind-fans at lists.skoll.ca> wrote:

> So in theory, it should be easy to take the Hebrew calendar logic,
> remove the "Leap Month" logic, and end up with a Muslim calendar.

Nope. :) The Hebrew calendar has additional tweaks, for example a
requirement that Yom Kippur never fall on a Friday or a Sunday.

If anyone is interested in trying to implement support for the Islamic
calendar, I recommend having a good read of this book:

https://www.amazon.ca/Calendrical-Calculations-Ultimate-Edward-Reingold/dp/1107683165

Check your local library... it was in mine.  Warning: It's heavy going and
they implement their algorithms in Lisp.  Reworking them in C in a way that
fits neatly into the Remind way of doing things is not a small task.

In addition, some calendars are based on observations and don't even
have any sort of algorithm you can implement on a computer.  (I think
there is a standard algorithmic way to compute the Islamic calendar,
but I don't know whether or not it's universally accepted.)

Regards,

Dianne.