Easter-Pascha Date

A project made for finding Easter’s date with Gauss’s Algorithm.

The symbolism [x]n = (x mod n) is used to denote the remainder of the division x divided by n. Also, the symbol Y is used to represent a year.

Some definitions and explanations of the following terms have been provided:

• Metonic Cycle
• Golden Number of a year

  golden_number(year) = [Y]19 + 1
  gn(Y) = [Y]19 + 1

• Epact of a year

  E[Y] = [11 · (gn(Y) - 1) + 8]30
  E[Y] = [11 · gn(Y) - 3]30

• Pascha Full Moon date

  2 + [19 · [Y]19 + 16]30 of April

For a complete overview of the project you can read the PDF file “Finding the date of Easter with Gauss’s Algorithm: An implementation in Python”, in which the above definitions are explained in detail. You are free to use this file, just leave a reference to its URL.

In addition, at the end of the work, both Orthodox and Catholic Easter dates for the years 2000 to 2100 are presented. The years where Orthodox and Catholic dates coincide are highlighted. Below you can see a part of the results for the years 2000 to 2055.

All the mathematical calculations and algorithms presented in this work have also been implemented in Python for a clearer picture of the results — Python file: easter_date.py. View file in Github.