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no more <literal> with PHP (versions) replace literal with meaningful tags where appropriate git-svn-id: https://svn.php.net/repository/phpdoc/en/trunk@165937 c90b9560-bf6c-de11-be94-00142212c4b1
101 lines
3.4 KiB
XML
101 lines
3.4 KiB
XML
<?xml version="1.0" encoding="iso-8859-1"?>
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<!-- $Revision: 1.11 $ -->
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<!-- splitted from ./en/functions/calendar.xml, last change in rev 1.2 -->
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<refentry id="function.easter-days">
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<refnamediv>
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<refname>easter_days</refname>
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<refpurpose>
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Get number of days after March 21 on which Easter falls for a
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given year
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</refpurpose>
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</refnamediv>
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<refsect1>
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<title>Description</title>
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<methodsynopsis>
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<type>int</type><methodname>easter_days</methodname>
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<methodparam choice="opt"><type>int</type><parameter>year</parameter></methodparam>
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<methodparam choice="opt"><type>int</type><parameter>method</parameter></methodparam>
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</methodsynopsis>
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<para>
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Returns the number of days after March 21 on which Easter falls
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for a given year. If no year is specified, the current year is
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assumed.
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</para>
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<para>
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Since PHP 4.3.0, the <parameter>year</parameter>
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parameter is optional and defaults to the current year according to the
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localtime if omitted.
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</para>
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<para>
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The <parameter>method</parameter> parameter was also introduced in
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PHP 4.3.0 and allows to calculate easter dates based
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on the Gregorian calendar during the years 1582 - 1752 when set to
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<constant>CAL_EASTER_ROMAN</constant>. See the <link
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linkend="calendar.constants">calendar constants</link> for more valid
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constants.
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</para>
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<para>
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This function can be used instead of
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<function>easter_date</function> to calculate Easter for years
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which fall outside the range of Unix timestamps (i.e. before 1970
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or after 2037).
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<example>
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<title><function>easter_days</function> example</title>
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<programlisting role="php">
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<![CDATA[
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<?php
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echo easter_days(1999); // 14, i.e. April 4
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echo easter_days(1492); // 32, i.e. April 22
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echo easter_days(1913); // 2, i.e. March 23
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?>
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]]>
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</programlisting>
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</example>
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</para>
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<para>
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The date of Easter Day was defined by the Council of Nicaea in
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AD325 as the Sunday after the first full moon which falls on or
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after the Spring Equinox. The Equinox is assumed to always fall
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on 21st March, so the calculation reduces to determining the date
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of the full moon and the date of the following Sunday. The
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algorithm used here was introduced around the year 532 by
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Dionysius Exiguus. Under the Julian Calendar (for years before
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1753) a simple 19-year cycle is used to track the phases of the
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Moon. Under the Gregorian Calendar (for years after 1753 -
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devised by Clavius and Lilius, and introduced by Pope Gregory
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XIII in October 1582, and into Britain and its then colonies in
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September 1752) two correction factors are added to make the
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cycle more accurate.
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</para>
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<para>
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(The code is based on a C program by Simon Kershaw,
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<webmaster at ely.anglican dot org>)
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</para>
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<para>
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See also <function>easter_date</function>.
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</para>
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</refsect1>
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</refentry>
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<!-- Keep this comment at the end of the file
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Local variables:
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mode: sgml
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sgml-omittag:t
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sgml-shorttag:t
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sgml-minimize-attributes:nil
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sgml-always-quote-attributes:t
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sgml-indent-step:1
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sgml-indent-data:t
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indent-tabs-mode:nil
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sgml-parent-document:nil
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sgml-default-dtd-file:"../../../../manual.ced"
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sgml-exposed-tags:nil
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sgml-local-catalogs:nil
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sgml-local-ecat-files:nil
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End:
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vim600: syn=xml fen fdm=syntax fdl=2 si
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vim: et tw=78 syn=sgml
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vi: ts=1 sw=1
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-->
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