CalCal — Calendrical Calculations

This is a pure Ruby implementation of several calendrical calculations algorithms.

Most of the algorithms are based on the book "Calendrical Calculations", 3rd edition written by Edward M. Reingold and Nachum Dershowitz.

Description

This library:

• allows easy dates conversion from/to different calendars.
• provides convenient functions to compare dates (even if they are expressed in different calendars!).
• provides basics arithmetic functions (add/subtract days, compute a difference in days between two dates, ...).

Example

require 'calcal'

today = CalCal::Gregorian.new(2014, 1, 26)    # 2014/01/26, in Gregorian calendar.
egypt = CalCal::Egyptian.from_rd(today.to_rd) # Convert from Gregorian calendar to Egyptian calendar
today == egypt # return true (same date but in different calendars).

today + 6      # return 2014/02/01
today - 26     # return 2013/12/31
today - egypt  # return 0

CalCal::Gregorian.new(2014, 1, 26).valid? # return true
CalCal::Gregorian.new(2012, 2, 29).valid? # return true
CalCal::Gregorian.new(2013, 2, 29).valid? # return false

Supported calendars

• Egyptian
• Armenian
• Gregorian

Install

$ gem build calcal.gemspec
$ gem install calcal-X.Y.Z.gem

Testing

To run the tests:

$ rake

Reference

Nachum Dershowitz, Edward M. Reingold "Calendrical Calculations" Cambridge University Press; 3rd edition (December 10, 2007); Paperback; ISBN-13: 9780521702386