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<?xml version="1.0" encoding="ISO-8859-1"?>
<!--
-
- This file is part of the OpenLink Software Virtuoso Open-Source (VOS)
- project.
-
- Copyright (C) 1998-2018 OpenLink Software
-
- This project is free software; you can redistribute it and/or modify it
- under the terms of the GNU General Public License as published by the
- Free Software Foundation; only version 2 of the License, dated June 1991.
-
- This program is distributed in the hope that it will be useful, but
- WITHOUT ANY WARRANTY; without even the implied warranty of
- MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
- General Public License for more details.
-
- You should have received a copy of the GNU General Public License along
- with this program; if not, write to the Free Software Foundation, Inc.,
- 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
-
-
-->
<refentry id="fn_log">
<refmeta>
<refentrytitle>log</refentrytitle>
<refmiscinfo>number</refmiscinfo>
</refmeta>
<refnamediv>
<refname>log</refname>
<refpurpose>calculate natural logarithm of an expression</refpurpose>
</refnamediv>
<refsynopsisdiv>
<funcsynopsis id="fsyn_log">
<funcprototype id="fproto_log">
<funcdef><function>log</function></funcdef>
<paramdef>in <parameter>x</parameter> double precision</paramdef>
</funcprototype>
</funcsynopsis>
</refsynopsisdiv>
<refsect1 id="desc_log"><title>Description</title>
<para><function>log</function> calculates the natural logarithm of its
argument and returns it as a IEEE 64-bit float.</para>
</refsect1>
<refsect1 id="params_log"><title>Parameters</title>
<refsect2><title>x</title>
<para><type>double precision</type></para>
</refsect2>
</refsect1>
<refsect1 id="ret_log"><title>Return Values</title>
<para><function>log</function>.</para>
</refsect1>
<refsect1 id="examples_log"><title>Examples</title>
<example id="ex_log"><title>Simple Examples</title>
<screen>
SQL> select concat ('the LOG of 0.513513 is: ', cast (log (0.513513) as varchar));
callret
VARCHAR
_______________________________________________________________________________
the LOG of 0.513513 is: -0.666480
1 Rows. -- 4 msec.
</screen>
</example>
</refsect1>
<refsect1 id="seealso_log"><title>See Also</title>
<para>
<link linkend="fn_exp"><function>exp</function></link>,
<link linkend="fn_log10"><function>log10</function></link>,
<link linkend="fn_power"><function>power</function></link>,
<link linkend="fn_sqrt"><function>sqrt</function></link>
</para>
</refsect1>
</refentry>
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