php-doc-en/reference/math/functions/log1p.xml
2020-12-26 19:26:31 +00:00

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XML

<?xml version="1.0" encoding="utf-8"?>
<!-- $Revision$ -->
<refentry xmlns="http://docbook.org/ns/docbook" xml:id="function.log1p">
<refnamediv>
<refname>log1p</refname>
<refpurpose>
Returns log(1 + number), computed in a way that is accurate even when
the value of number is close to zero
</refpurpose>
</refnamediv>
<refsect1 role="description">
&reftitle.description;
<methodsynopsis>
<type>float</type><methodname>log1p</methodname>
<methodparam><type>float</type><parameter>num</parameter></methodparam>
</methodsynopsis>
<para>
<function>log1p</function> returns log(1 +
<parameter>num</parameter>) computed in a way that is accurate even
when the value of <parameter>num</parameter> is close to zero.
<function>log</function> might only return log(1) in this case
due to lack of precision.
</para>
</refsect1>
<refsect1 role="parameters">
&reftitle.parameters;
<para>
<variablelist>
<varlistentry>
<term><parameter>num</parameter></term>
<listitem>
<para>
The argument to process
</para>
</listitem>
</varlistentry>
</variablelist>
</para>
</refsect1>
<refsect1 role="returnvalues">
&reftitle.returnvalues;
<para>
log(1 + <parameter>num</parameter>)
</para>
</refsect1>
<refsect1 role="seealso">
&reftitle.seealso;
<para>
<simplelist>
<member><function>expm1</function></member>
<member><function>log</function></member>
<member><function>log10</function></member>
</simplelist>
</para>
</refsect1>
</refentry>
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