CALENDAR ALGORITHMS GALORE:

Israeli algorithms help you get your dates straight (Israel21c)
By Rava Eleasari July 19, 2004

The e-mail came from a Swede requesting that Tel Aviv University Professor Nachum Dershowitz look into the rules of the Samaritan calendar "since he was already there in Israel."

Thus began the latest odyssey of Dershowitz, a member of the School of Computer Science, Raymond and Beverly Sackler Faculty of Exact Sciences, in systemizing yet another of the world's dating systems - this time of a secretive, traditionalist religious sect of only 1,000 people that live in a radius of about 65 mile radius from the TAU campus.

To date, Dershowitz and his colleague Prof. Edward M. Reingold of the Illinois Institute of Technology, USA, have mathematically analyzed 25 of the world's calendars in the first and only project of its kind. They have provided equations and algorithms for quick and accurate calculation of dates within each system, as well as for conversion of dates between calendars.

The second edition of their book, Calendrical Calculations, encodes the rules for two dozen calendars in mathematical form, and describes how they relate to one another. Among the systems described are the Gregorian (in near universal use today), Islamic, Persian, Coptic, Baha'i, Hebrew, Mayan, Chinese, and modern Hindu. (www.calendarists.com

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