(PHP 3 = 3.0.9, PHP 4 )
Returns the number of days after March 21 on which
Easter falls for a given year. If no year is specified, the
current year is assumed.
Since PHP 4.3.0, the year parameter is optional and
defaults to the current year according to the localtime if
ommited.
The method parameter
was also introduced in PHP 4.3.0 and
allows to calculate easter dates based on the Gregorian
calendar during the years 1582 - 1752 when set to CAL_EASTER_ROMAN. See the calendar constants
for more valid constants.
This function can be used instead of
easter_date() to calculate Easter for years which
fall outside the range of UNIX timestamps (i.e. before 1970
or after 2037).
The date of Easter Day was defined by the Council of
Nicaea in AD325 as the Sunday after the first full moon which
falls on or after the Spring Equinox. The Equinox is assumed
to always fall on 21st March, so the calculation reduces to
determining the date of the full moon and the date of the
following Sunday. The algorithm used here was introduced
around the year 532 by Dionysius Exiguus. Under the Julian
Calendar (for years before 1753) a simple 19-year cycle is
used to track the phases of the Moon. Under the Gregorian
Calendar (for years after 1753 - devised by Clavius and
Lilius, and introduced by Pope Gregory XIII in October 1582,
and into Britain and its then colonies in September 1752) two
correction factors are added to make the cycle more
accurate.
(The code is based on a C program by Simon Kershaw,
webmaster@ely.anglican.org )
See also easter_date().