Zeller's congruence

(algorithm)

Definition: An algorithm to find the day of the week for any date.

Author: PEB

Implementation

Dr J R Stockton's The Calendrical Works of Rektor Chr. Zeller: The Day-of-Week and Easter Formulae page has implementations of Zeller's congruence, for day-of-week (Pascal, JavaScript). The page includes tests and code for Easter, Zeller's original papers (and translations), etc. The following is only correct for Gregorian dates: Comp.lang.c FAQ question 17.28 (C).

More information

Wikipedia entry for Zeller's congruence. A summary of the International Standard Date and Time Notation ISO 8601. The full ISO 8601:2004 standard.

Christian Zeller, Kalender-Formeln, Acta Mathematica, 9:131-6, Nov 1886.

Go to the Dictionary of Algorithms and Data Structures home page.

If you have suggestions, corrections, or comments, please get in touch with Paul E. Black.

Entry modified 29 April 2009.
HTML page formatted Wed Apr 29 09:42:52 2009.

Cite this as:
Paul E. Black, "Zeller's congruence", in Dictionary of Algorithms and Data Structures [online], Paul E. Black, ed., U.S. National Institute of Standards and Technology. 29 April 2009. (accessed TODAY) Available from: http://www.itl.nist.gov/div897/sqg/dads/HTML/zellersCongruence.html