cal_to_jd
v5.2.1 - There is a known bug with easter_date() that can return incorrect dates for some years:
// 2008 OK
echo date("D d M Y", easter_date(2008)); // Sun 23 Mar 2008
// 2009 returns Saturday
echo date("D d M Y", easter_date(2009)); // Sat 11 Apr 2009
However easter_days() works correctly:
echo date("D d M Y", strtotime("2009-03-21 +".easter_days(2009)." days")); // Sun 12 Apr 2009
It is apparently related to timezone settings.
easter_date
(PHP 4, PHP 5)
easter_date — Get Unix timestamp for midnight on Easter of a given year
Description
int easter_date
([ int $year
] )
Returns the Unix timestamp corresponding to midnight on Easter of the given year.
Warning
This function will generate a warning if the year is outside of the range for 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 at ely.anglican dot org>)
Parameters
- year
-
The year as a number between 1970 an 2037
Return Values
The easter date as a unix timestamp.
ChangeLog
| Version | Description |
|---|---|
| Since 4.3.0 | The year parameter is optional and defaults to the current year according to the local time if omitted. |
Examples
Example #1 easter_date() example
<?php
echo date("M-d-Y", easter_date(1999)); // Apr-04-1999
echo date("M-d-Y", easter_date(2000)); // Apr-23-2000
echo date("M-d-Y", easter_date(2001)); // Apr-15-2001
?>
add a note
User Contributed Noteseaster_date
nigelf at esp dot co dot uk
28-Jan-2008 11:50
28-Jan-2008 11:50
14-Aug-2006 03:46
I made the function like this ... works fine !
function ostern
{
$maerz21=date('z',mktime(0,0,0,3,21,$jb));
$d=((15 + $jb/100 - $jb/400 - (8 * $jb/100 + 13) / 25)%30 + 19 * ($jb%19))%30;
if ($d==29)
{
$D=28;
}
elseif($d==28 && ($jb%17)>=11)
{
$D=27;
}
else $D=$d;
$e=(2 * ($jb%4) + 4 *($jb%7) + 6 * $D + (6 + $jb/100 - $jb/400 - 2)%7)%7;
$ostersonntag=$e+$D+1+$maerz21;
return $ostersonntag;
}
phpuser
08-Nov-2004 04:17
08-Nov-2004 04:17
The algorithm from Bigtree is correct if you add some (int) cast
<?php
function easter_date ($Year) {
/*
G is the Golden Number-1
H is 23-Epact (modulo 30)
I is the number of days from 21 March to the Paschal full moon
J is the weekday for the Paschal full moon (0=Sunday,
1=Monday, etc.)
L is the number of days from 21 March to the Sunday on or before
the Paschal full moon (a number between -6 and 28)
*/
$G = $Year % 19;
$C = (int)($Year / 100);
$H = (int)($C - (int)($C / 4) - (int)((8*$C+13) / 25) + 19*$G + 15) % 30;
$I = (int)$H - (int)($H / 28)*(1 - (int)($H / 28)*(int)(29 / ($H + 1))*((int)(21 - $G) / 11));
$J = ($Year + (int)($Year/4) + $I + 2 - $C + (int)($C/4)) % 7;
$L = $I - $J;
$m = 3 + (int)(($L + 40) / 44);
$d = $L + 28 - 31 * ((int)($m / 4));
$y = $Year;
$E = mktime(0,0,0, $m, $d, $y);
return $E;
}
?>
ray at non-aol dot com
07-Nov-2004 12:49
07-Nov-2004 12:49
The algorithm from BigTree will throw an error in 2021 and 2025. Better to install the PHP functions! Details here:
http://aa.usno.navy.mil/faq/docs/easter.html
bigtree at 29a dot DONTSPAM dot nl
17-May-2002 04:41
17-May-2002 04:41
A much smaller hack is the following. I ported this from a Delphi implementation of a function calculating easter dates.
<?php
function easter_date ($Year) {
/*
G is the Golden Number-1
H is 23-Epact (modulo 30)
I is the number of days from 21 March to the Paschal full moon
J is the weekday for the Paschal full moon (0=Sunday,
1=Monday, etc.)
L is the number of days from 21 March to the Sunday on or before
the Paschal full moon (a number between -6 and 28)
*/
$G = $Year % 19;
$C = (int)($Year / 100);
$H = (int)($C - ($C / 4) - ((8*$C+13) / 25) + 19*$G + 15) % 30;
$I = (int)$H - (int)($H / 28)*(1 - (int)($H / 28)*(int)(29 / ($H + 1))*((int)(21 - $G) / 11));
$J = ($Year + (int)($Year/4) + $I + 2 - $C + (int)($C/4)) % 7;
$L = $I - $J;
$m = 3 + (int)(($L + 40) / 44);
$d = $L + 28 - 31 * ((int)($m / 4));
$y = $Year;
$E = mktime(0,0,0, $m, $d, $y);
return $E;
}
?>