Paschalia of Orthodox Church: methods of calculating the date of Easter.

Abstract

Aim of this paper is to show how the Orthodox Church calculates date of Easter. On the basis of historical evidence it indicates the assumptions of the Paschalia system from the second century to the modern days. Paper explains differences between Julian, Gregorian and revised Julian calendars and shows how to calculate the date of Easter in present days. The text also discusses the problems of imperfection and errors, and calendars on their basis shows suggestions for their correction. The result of this paper is the development of Paschal table for the Gregorian and Julian calendars for the years 2012–2105, together with an indication of the mathematical formula built on the basis of existing Meuus and Gauus algorithms.