Anssi Seppälä wrote: > My experience is that the APL/J calendrical algorithms are allways > unreliable. The testing is allways insufficient. My choice was to buy > Reingold&Dershowiz: Calendrical Tabulations 1900 - 2200. There I find > reliable data and put that into the applications.
FWIW with regard to this discussion: I believe that the better book is the 2nd edition of the same authors' "Calendrical Calculations" because it gives the formulas and algorithms that one would use in computer programming. The story of trying to "nail jelly to a tree" for some of the world's calendar systems is a quite interesting narrative in itself because of all the exceptions and sometimes near impossibility of translating them to computer code (Lisp and Java). You can see the Amazon citation at: <http://www.amazon.com/Calendrical-Calculations-Millennium-Edward- Reingold/dp/0521777526>. This book should be in every programmer's "top 100" (maybe even "top 25"). The only other book worth its weight in gold for information on time- related phenomena (such as calendars and other celestial timings) is the "Explanatory Supplement to the Astronomical Almanac". For obvious reasons, astronomers are extremely concerned about accuracy related to time. The Amazon citation is at: <http://www.amazon.com/Explanatory- Supplement-Astronomical-Almanac-Seidelmann/dp/1891389459>. Harvey ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm
