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OrthCalKAOV is an application that provides support for both the Old Calendar (Julian Calendar) and the New Calendar (Revised Julian Calendar) for the years 1925 to 2099.

Early Modern Dates

A C implementation of most of the book "Calendrical Calculations".

An Orthodox and Catholic Easter Date Calculator

Multilingual Orthodox Liturgical Calendar Dataset (Old and New Calendar 1924 - 2099)

A Swift framework containing an astronomical model of the Moon, including properties to obtain the age, percent illuminated, phase, transitions, and other properties of the Moon at a point in time. This is a Swift port of John Walker's `moontool.c`, originally written in 1987.

Convert between Julian day numbers and Julian & Gregorian calendars

Julian date calculations and calendar conversions for Swift

jcalendaR is a package for converting between current Japanese calendar, old Japanese calendar that Kyureki, and Julian and (proleptic) Gregorian calendar in R.

Converts a gregorian date to julian date.

The project is a collection of functions to convert dates between Gregorian and Julian calendars. Additionally it includes functions to calculate Orthodox and Catholic Easter dates.

Calendar implementation using object-oriented principles in C++.

An implementation of the Roman calendar post-Julian reforms (46 BC)

Selected development examples from Numerical Recipes in FORTRAN 77