Rosh Hashana Calculations

[Brendan McKay]

* Hans Havermann <pxp at rogers.com> [060925 17:54]:
> 
> ... which is "adapted from Winning Ways for Your Mathematical Plays"  
> and gives (on page 6) a formula for computing Rosh Hashana that I was  
> able to implement in Mathematica. All of the calculated dates (except  
> two) matched the Webster "begins" dates. The two exceptions are:
> 
> 1907 - Webster, begins Sept. 6. Formula suggests Sept. 9.
> 1933 - Webster, begins Sept.23. Formula suggests Sept.21.
> 
> If these two Webster dates are in fact misprints and replaced with  

The formula is correct in both these cases. The Jewish calendar
is difficult to compute correctly as some calculations need to be
done in integer arithmetic using integers greater than 32 bits
(floating point won't do). If you have a Macintosh, a well tested
implementation is InterCal:
   http://intercal.denisandjill.net/
A Jewish calendar on the web that has been thoroughly tested is here:
   http://www.jewishgen.org/jos/

Brendan.