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.

Selected development examples from Numerical Recipes in FORTRAN 77

Python script that generates structured JSON data for each liturgical day of the year, including details about commemorations, fasting, moon phases, and other relevant information.

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

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

Early Modern Dates

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

Julian date calculations and calendar conversions for Swift

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

An Orthodox and Catholic Easter Date Calculator

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.

Convert between Julian day numbers and Julian & Gregorian calendars

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.

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