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-- Easter.DT - an addition to DateTime.e - 2003 CyrekSoft --
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 This document serves to describe the Easter.DT sub-library for the
 DateTime.e library for the Euphoria programming language.

 The function of this sub-library was kept separate since the code used is
 not original and therefore not within the idiom of the main library.

 1. Notes on Easter
 ==================

 The first ever Easter is said to have fallen around 33AD (To paraphrase
 Douglas Adams - Shortly after someone was nailed to a tree for suggesting
 that people be nice to each other for a change.)

 Furthermore, the Church itself did not introduce the Easter festival into
 its calendar until the middle of the 4th century.

 The current festival is a combination of the Jewish Passover festival (in
 which lies the origin of Lent) and a Pagan spring-rites celebration derived
 from the Vernal Equinox (in which lies the origins of Easter eggs, fluffy
 yellow Easter chicks and the Easter bunny).

 In fact the word 'Easter' is derived from the name of an old English Pagan
 goddess of fertility and spring - 'Eostre'.

 Perhaps not coincidentally, Christmas - the other major Christian festival
 - falls shortly after the Winter Solstice, another Pagan festival.
 (Decorating a tree is a solstice tradition.)


 2. Function Definitions
 =======================

 See Section 3. of DateTime.txt for the documentation conventions used here.

 ÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄ<easterSunday>ÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄ

 Syntax:      d = easterSunday(i)

 Description: Returns the Date of the Christian Easter festival for a given
              year.

 Comments:    Many dates in the Christian calendar are calculated from the
              date of Easter Sunday. For instance, Shrove Tuesday, known as
              Mardi Gras in many countries, always falls precisely 47 days
              before Easter. Pentecost (or Whit Sunday) falls 7 weeks after.

 Warning:     The author of Datetime.e did not write, and therefore cannot
              guarantee results obtained by the use of, the algorithm within
              this function.

              Please note that this function will accept any year accepted
              by DateTime.e; even those for which the Christian Easter was
              not known of nor celebrated.

 Example 1:   include datetime.e
              include easter.dt

              Date d

              d = easterSunday(2003) -- d = {2003, 4, 20}

              -- Easter Sunday in 2003 falls on the 20th of April.

 Example 2:   include datetime.e
              include easter.dt

              Date d

              d = subFromDate(easterSunday(2004), 46) -- d = {2004, 2, 25}

              -- Ash Wednesday marks the beginning of Lent, and in 2004
              -- falls on the 25th of February.