<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> <HTML ><HEAD ><TITLE >log</TITLE ><META NAME="GENERATOR" CONTENT="Modular DocBook HTML Stylesheet Version 1.79"><LINK REL="HOME" TITLE="Manual do PHP" HREF="index.html"><LINK REL="UP" TITLE="Matemática e Trigonometria" HREF="ref.math.html"><LINK REL="PREVIOUS" TITLE="log1p" HREF="function.log1p.html"><LINK REL="NEXT" TITLE="max" HREF="function.max.html"><META HTTP-EQUIV="Content-type" CONTENT="text/html; charset=UTF-8"></HEAD ><BODY CLASS="refentry" BGCOLOR="#FFFFFF" TEXT="#000000" LINK="#0000FF" VLINK="#840084" ALINK="#0000FF" ><DIV CLASS="NAVHEADER" ><TABLE SUMMARY="Header navigation table" WIDTH="100%" BORDER="0" CELLPADDING="0" CELLSPACING="0" ><TR ><TH COLSPAN="3" ALIGN="center" >Manual do PHP</TH ></TR ><TR ><TD WIDTH="10%" ALIGN="left" VALIGN="bottom" ><A HREF="function.log1p.html" ACCESSKEY="P" >Anterior</A ></TD ><TD WIDTH="80%" ALIGN="center" VALIGN="bottom" ></TD ><TD WIDTH="10%" ALIGN="right" VALIGN="bottom" ><A HREF="function.max.html" ACCESSKEY="N" >Próxima</A ></TD ></TR ></TABLE ><HR ALIGN="LEFT" WIDTH="100%"></DIV ><H1 ><A NAME="function.log" ></A >log</H1 ><DIV CLASS="refnamediv" ><A NAME="AEN104943" ></A ><P > (PHP 3, PHP 4, PHP 5)</P >log -- Logaritmo natural</DIV ><DIV CLASS="refsect1" ><A NAME="AEN104946" ></A ><H2 >Descrição</H2 >float <B CLASS="methodname" >log</B > ( float arg [, float base] )<BR ></BR ><P > Se o parâmetro opcional <CODE CLASS="parameter" >base</CODE > for informado, <B CLASS="function" >log()</B > retorna log<SUB >base</SUB > <CODE CLASS="parameter" >arg</CODE >, senão <B CLASS="function" >log()</B > retorna o logaritmo natural de <CODE CLASS="parameter" >arg</CODE >. </P ><DIV CLASS="note" ><BLOCKQUOTE CLASS="note" ><P ><B >Nota: </B > O parâmetro <CODE CLASS="parameter" >base</CODE > foi acrescentado no PHP versão 4.3.0. </P ><P > Você sempre pode calcular o logatitmo na base <TT CLASS="literal" >b</TT > de um número <TT CLASS="literal" >n</TT > pela utilização da identidade matemática: log<SUB >b</SUB >(n) = log(n)/log(b), onde log é o logaritmo neperiano (ou natural). </P ></BLOCKQUOTE ></DIV ><P > Veja também <A HREF="function.exp.html" ><B CLASS="function" >exp()</B ></A >. </P ></DIV ><DIV CLASS="NAVFOOTER" ><HR ALIGN="LEFT" WIDTH="100%"><TABLE SUMMARY="Footer navigation table" WIDTH="100%" BORDER="0" CELLPADDING="0" CELLSPACING="0" ><TR ><TD WIDTH="33%" ALIGN="left" VALIGN="top" ><A HREF="function.log1p.html" ACCESSKEY="P" >Anterior</A ></TD ><TD WIDTH="34%" ALIGN="center" VALIGN="top" ><A HREF="index.html" ACCESSKEY="H" >Principal</A ></TD ><TD WIDTH="33%" ALIGN="right" VALIGN="top" ><A HREF="function.max.html" ACCESSKEY="N" >Próxima</A ></TD ></TR ><TR ><TD WIDTH="33%" ALIGN="left" VALIGN="top" >log1p</TD ><TD WIDTH="34%" ALIGN="center" VALIGN="top" ><A HREF="ref.math.html" ACCESSKEY="U" >Acima</A ></TD ><TD WIDTH="33%" ALIGN="right" VALIGN="top" >max</TD ></TR ></TABLE ></DIV ></BODY ></HTML >