Calendrical works by Svante Janson, Department of Mathematics, Uppsala University.

Papers on calendars

Computer implementations

The following files contain program code in Maple for various calendrical calculations and conversions.

Disclaimer: There is no guarantee that these procedures are correct. They have been written for my own use and mainly to experiment and explore, and are not in any final, polished form (and presumably never will be). They are sometimes written in English, sometimes in Swedish. The documentation is at best incomplete, and again sometimes in English, sometimes in Swedish. There is (unfortunately) no further documentation (although the paper above gives some background). There is no support.

Nevertheless, the procedures are made available here so that anyone seriously interested may use them as inspiration for own programming (possibly in other languages). The files may be freely used and modified for non-commercial purposes.

For well documented computer implementations, see instead Calendrical Calculations by Edward M. Reingold and Nachum Dershowitz, Cambridge University Press, 3rd edition, 2008.