The physicist Carl Friedrich Gauss (1777-1855) developed the Gauss algorithm. The algorithm calculates the sunday of Easter for any year without knowing the moon calendar.
Physikalisch-Technische Bundesanstalt (PTB)
In the Gauss algorithm has exceptions, these were extended by Dr Heiner Lichtenberg.
This PHP script contains the adaptations of Lichtenberg.
- The sunday of Easter for Gregorian calendar
- The sunday of Easter for Julian calendar of orthodox