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https://github.com/sigmasternchen/php-doc-en
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86 lines
3 KiB
XML
86 lines
3 KiB
XML
<?xml version="1.0" encoding="iso-8859-1"?>
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<!-- $Revision: 1.3 $ -->
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<!-- splitted from ./en/functions/calendar.xml, last change in rev 1.2 -->
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<refentry id="function.easter-date">
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<refnamediv>
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<refname>easter_date</refname>
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<refpurpose>
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Get UNIX timestamp for midnight on Easter of a 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_date</methodname>
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<methodparam choice="opt"><type>int</type><parameter>year</parameter></methodparam>
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</methodsynopsis>
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<para>
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Returns the UNIX timestamp corresponding to midnight on Easter of
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the given year.
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</para>
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<para>
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Since <literal>PHP</literal> 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 ommited.
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</para>
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<para>
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<emphasis>Warning:</emphasis> This function will generate
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a warning if the year is outside of the range for UNIX
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timestamps (i.e. before 1970 or after 2037).
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<example>
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<title><function>easter_date</function> example</title>
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<programlisting role="php">
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<![CDATA[
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echo date ("M-d-Y", easter_date(1999)); /* "Apr-04-1999" */
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echo date ("M-d-Y", easter_date(2000)); /* "Apr-23-2000" */
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echo date ("M-d-Y", easter_date(2001)); /* "Apr-15-2001" */
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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@ely.anglican.org>)
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</para>
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<para>
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See <function>easter_days</function> for calculating Easter
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before 1970 or after 2037.
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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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