Re: [libreoffice-users] Islamic Calendar Dates

On 11/12/22 04:53, John Kaufmann wrote:

> When I found the questions interesting, I did not imagine how 
> interesting: that the last day of each month is also the first day of 
> the following month -- not just for Shaʿbān to Ramadan, but for all 
> monthly transitions. The implications are fascinating.

There is a reason why serious developers point blank refuse to write 
their own calendar library.

> That said, your use of "12th hour" suggests that "sunset" and "sunrise" 
> are (like Gregorian "midnight") formal based on a 24-hour day, not 
> literal - correct?

It depends.
* Sometimes one uses a standard clock, that breaks a day into 24 hours 
of 60 minutes each;
* Sometimes one uses a time piece that breaks the time between sunset 
and sunrise into 12 hours, and between sunrise and sunset into 12 hours, 
with the length of the hours during daylight being different from those 
during the night. By way of example, where I am, the hours at night are 
roughly 80 minutes long, whilst the hours during the day are roughly 40 
minutes long. Twelfth hour being at roughly 6 AM, with sunrise at 
roughly 7:45 AM, then the next 12th hour is at roughly roughly 3:30 PM, 
with sunset at roughly 4:15 PM.
* Sometimes one uses a time piece that breaks the day into 12 hours, and 
the night into either 3 or 4 watches.

#####

I'm going to assume that LibO starts both the day, and the month at 
sunset. For when the exact day is critical, I'll run a script that 
calculates when the new moon was first _theoretically_ sighted in Mecca, 
Medina, and Jerusalem.

jonathon


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