This is an interesting little book that provides a unified algorithmic presentation for more than two dozen calendars of current and historical interest. The book gives precise descriptions of each calendar and makes accurate calendar algorithms available for computer programmers. The complete workings of each calendar are described in verbage and then mathematically. Working computer programs are included in an appendix and on the accompanying CD.

The one thing I didn't care for was the choice of Lisp as the implementation language in appendix B. However, this isn't too big of a problem since equivalent Java programs are on the book's website along with the Lisp implementations. Also, since the mathematical equations of conversion are clearly given, you can choose your own implementation language with few problems. The following is the table of contents:

1. Introduction

Part I. Arithmetical Calendars:

2. The Gregorian calendar

3. The Julian calendar

4. The Coptic and Ethiopic calendars

5. The ISO calendar

6. The Islamic calendar

7. The Hebrew calendar

8. The Ecclesiastical calendars

9. The Old Hindu calendars

10. The Mayan calendar

11. The Balinese Pawukon calendar

12. Generic cyclical calendars

Part II. Astronomical Calendars:

13. Time and astronomy

14. The Persian calendar

15. The Baha'i calendar

16. The French Revolutionary calendar

17. The Chinese calendar

18. The modern Hindu calendars

19. The Tibetan calendar

20. Astronomical lunar calendars coda

Part III. Appendices:

A. Function, parameter, and constant types

B. Lisp implementation

C. Sample data.

If you need to calculate a leap month start in a traditional Korean calendar this is a book for you. As far as I have found, this is the only source of such information, covering majority of world calendars.

You like technology references and information this book is for you. Chock full of information. Excellent reference.

thank you

The choice of licensing and threatening with unpublished patents make this otherwise excellent book completely unusable.

An excellent book on the history and workings of various calendars. But don’t use the source code! The licensing agreement is a trap. Use the code in GNU Emacs from the Free Software Foundation distributed under the General Public License. It does everything the authors code does (except for two obscure calendars) and it's free and always will be.

I am amazed by the clarity and "simplicity" of the text in the book.

Calendars are not simple at all, but the approach taken by the authors makes the algorithms involved very accessible. I also appreciated the decision to focus on clarity rather then performance.

This book contains conversion routines for many of the world calendars (ancient and modern). It also contains some hisorical background. More especially, it contains excellent algorithms for the astronomical calculations needed to calculate Moon and Equinox positions needed for calendars that are Lunar or Equinox related (such as the Chinese and Original French Revolutionary Calendar). The explanation of the algorithms and descriptions of the exact details of calculation of calendars is extremely clear and well researched.

Another book along the same lines is the Standard C Date/Time Library by Lance Latham which is much thicker, covers more calendars and contains more historical information of calendars origin - but lacks the astronomical calculations contained in this book by Dershowitz and Reingold.

Reviewed by Ira J. Lund, author of the Universal Calendar Calculator.

to be precise when i started reading it to get worth for my money ,it seemed to me of no use. but i kept reading it to get something out of it. and finally it remembered me of RD sharma of maths in class XIIth that was a gita of maths. how its knowledge would benefit me in the present or future , i am totally unaware about it.it would be revealed to me in future.

as this purchase was totally out of purpose for me and entirely based on recommendations by amazon & its reviews. it has taught me this thing that in future i would need to put one this in my mind that i need to honour suggestions/advices of all that are beneficial/detrimental to my cause , but the final decision shall be mine. otherwise i would end up wasting my valuable resources like money that could have served me a better purpose other than this.

Falls es ihnen langweilig ist und sie etwas zum Nachdenken benötigen - probieren sie doch mal ein Datum aus dem Maya Kalender in den Iranischen umzurechnen. Wenn das nichts für sie ist - nicht weiterlesen. An sonsten bitte erst Freitags mit dem Lesen anfangen, es könnte sie einen Schlafzyklus kosten, wenn sie nicht vorsichtig sind...

I bought this book to help me create calendrical algorithms in PHP for a web page, and it has been an excellent resource for this purpose. However, some of the calculations are very complicated and it was difficult to translate these from the LISP listings in the book into PHP or Javascript. And, unlike the Millennium edition, it does not come with the CD with code in Java and LISP in electronic form. However, one of the authors was kind enough to send me a CD when I asked him some questions about the code, so I still give this five stars.

Very informative. Code download option my be given.

-S.Raja

Detailed and comprehensive. For one who has studied the subject - thought provoking.