cal-persia.el disagrees with Iranian calendar in A.D. 2025
reingold at emr.cs.iit.edu
Wed Apr 6 16:30:32 UTC 2005
> On Tue, 2005-04-05 at 15:02 -0700, Paul Eggert wrote:
> > This suggests that cal-persia.el could be changed as well, as its
> > practical use is (I think) for predicting dates in Iran. I'm hesitant
> > to propose a change myself, though, as I'm not an expert in either the
> > calendar or the code.
> Ed could probably help with that... I don't know any LISP, and every
> useful thing I know about computing astronomical calendars comes from
> his book.
As I have said before, the mechanisms needed to do the Persian astronomical
calendar are not in the existing Emacs code; the algorithms in my Calendrical
Calculations will never be released under the GNU license, so somebody would
have to come up with entirely new algorithms and implement them in Emacs-Lisp.
As it stands, the arithmetical Persian calendar is an excellent approximation
to the astronomical version--a much better approximation than the GNU Emacs
arithmetic approximation to the Islamic calendar is to the true observational
I don't see any reasonable changes to cal-persia.el as being needed. The
documentation could be modified to state that the calendar as implemented is
a close approximation to the astronomical version. I leave that up to others.
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