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<?xml version="1.0" encoding="iso-8859-1"?>
<!-- $Revision: 1.13 $ -->
<refentry xml:id="function.pow" xmlns="http://docbook.org/ns/docbook">
<refnamediv>
<refname>pow</refname>
<refpurpose>Exponential expression</refpurpose>
</refnamediv>
<refsect1 role="description">
&reftitle.description;
<methodsynopsis>
<type>number</type><methodname>pow</methodname>
<methodparam><type>number</type><parameter>base</parameter></methodparam>
<methodparam><type>number</type><parameter>exp</parameter></methodparam>
</methodsynopsis>
<para>
Returns <parameter>base</parameter> raised to the power of
<parameter>exp</parameter>.
</para>
<warning>
<para>
In PHP 4.0.6 and earlier <function>pow</function> always returned
a <type>float</type>, and did not issue warnings.
</para>
</warning>
</refsect1>
<refsect1 role="parameters">
&reftitle.parameters;
<para>
<variablelist>
<varlistentry>
<term><parameter>base</parameter></term>
<listitem>
<para>
The base to use
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><parameter>exp</parameter></term>
<listitem>
<para>
The exponent
</para>
</listitem>
</varlistentry>
</variablelist>
</para>
</refsect1>
<refsect1 role="returnvalues">
&reftitle.returnvalues;
<para>
<parameter>base</parameter> raised to the power of <parameter>exp</parameter>.
If the result can be represented as integer it will be returned as type
<type>integer</type>, else it will be returned as type <type>float</type>.
If the power cannot be computed &false; will be returned instead.
</para>
</refsect1>
<refsect1 role="changelog">
&reftitle.changelog;
<para>
<informaltable>
<tgroup cols="2">
<thead>
<row>
<entry>&Version;</entry>
<entry>&Description;</entry>
</row>
</thead>
<tbody>
<row>
<entry>Since 4.0.6</entry>
<entry>
The function will now return <type>integer</type> results if possible,
before this it always returned a <type>float</type> result. For older
versions, you may receive a bogus result for complex numbers.
</entry>
</row>
<row>
<entry>Since 4.2.0</entry>
<entry>
PHP stops to emit a warning if the value can't be computed,
it will now silently return &false; only.
</entry>
</row>
</tbody>
</tgroup>
</informaltable>
</para>
</refsect1>
<refsect1 role="examples">
&reftitle.examples;
<para>
<example>
<title>Some examples of <function>pow</function></title>
<programlisting role="php">
<![CDATA[
<?php
var_dump(pow(2, 8)); // int(256)
echo pow(-1, 20); // 1
echo pow(0, 0); // 1
echo pow(-1, 5.5); // PHP >4.0.6 NAN
echo pow(-1, 5.5); // PHP <=4.0.6 1.#IND
?>
]]>
</programlisting>
</example>
</para>
</refsect1>
<refsect1 role="seealso">
&reftitle.seealso;
<para>
<simplelist>
<member><function>exp</function></member>
<member><function>sqrt</function></member>
<member><function>bcpow</function></member>
<member><function>gmp_pow</function></member>
</simplelist>
</para>
</refsect1>
</refentry>
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