Several years ago, while rewriting my genealogy program, NEWGEN, I decided that a routine to convert dates from the Julian calendar to the Gregorian calendar and vice versa would be useful. After I had written these, it seemed it would be useful to be able to convert dates in the Jewish and Islamic calendars as well.  This sparked my interest in Calendars and the result was programs for the Atari ST(E) and for PCs called CALENDAR.  It then seemed that some explanatory text describing the various calendars might be useful. This lead , after several years research, to Mapping Time.

My book is a popular account of the calendars of the world and includes simple algorithms for calculating the day of the week of any date, for interconverting dates in a variety of calendars and for calculating the date of Easter. They are all suitable for use with a hand calculator, or if you prefer, you can write a simple computer program which uses them.

You can download an ASCII file containing all the algorithms:  Download Algorithms (17.9 Kb)

You can also download an extended version of Chapters 23 and 25 which contains a detailed discussion together with full derivations of  the formulae in these chapters for interconverting calendars:   Download Mathematics (73 Kb)

Errata

If you discover any misprints or errors not already listed, please E-mail them to me.

Errors found in the first printing are listed in                                                                    Errata 1
Errors found in the second printing are listed in                                                               Errata 2
Errors found in the paperback edition are listed in                                                           Errata 3
Further errors not listed in Errata 1, 2 or 3 and present in ALL editions and printings       Errata N