<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> <HTML ><HEAD ><TITLE >bcsqrt</TITLE ><META NAME="GENERATOR" CONTENT="Modular DocBook HTML Stylesheet Version 1.79"><LINK REL="HOME" TITLE="PHP 手册" HREF="index.html"><LINK REL="UP" TITLE="BC math 高精度数学函数" HREF="ref.bc.html"><LINK REL="PREVIOUS" TITLE="bcscale" HREF="function.bcscale.html"><LINK REL="NEXT" TITLE="bcsub" HREF="function.bcsub.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" >PHP 手册</TH ></TR ><TR ><TD WIDTH="10%" ALIGN="left" VALIGN="bottom" ><A HREF="function.bcscale.html" ACCESSKEY="P" >上一页</A ></TD ><TD WIDTH="80%" ALIGN="center" VALIGN="bottom" ></TD ><TD WIDTH="10%" ALIGN="right" VALIGN="bottom" ><A HREF="function.bcsub.html" ACCESSKEY="N" >下一页</A ></TD ></TR ></TABLE ><HR ALIGN="LEFT" WIDTH="100%"></DIV ><H1 ><A NAME="function.bcsqrt" ></A >bcsqrt</H1 ><DIV CLASS="refnamediv" ><A NAME="AEN14430" ></A ><P > (PHP 3, PHP 4, PHP 5)</P >bcsqrt -- Get the square root of an arbitrary precision number</DIV ><DIV CLASS="refsect1" ><A NAME="AEN14433" ></A ><H2 >说明</H2 >string <B CLASS="methodname" >bcsqrt</B > ( string operand [, int scale] )<BR ></BR ><P > Return the square root of the <CODE CLASS="parameter" >operand</CODE >. </P ></DIV ><DIV CLASS="refsect1" ><A NAME="AEN14446" ></A ><H2 >参数</H2 ><P > <P ></P ><DIV CLASS="variablelist" ><DL ><DT ><CODE CLASS="parameter" >operand</CODE ></DT ><DD ><P > The operand, as a string. </P ></DD ><DT ><CODE CLASS="parameter" > scale</CODE ></DT ><DD ><P >This optional parameter is used to set the number of digits after the decimal place in the result. You can also set the global default scale for all functions by using <A HREF="function.bcscale.html" ><B CLASS="function" >bcscale()</B ></A >.</P ></DD ></DL ></DIV > </P ></DIV ><DIV CLASS="refsect1" ><A NAME="AEN14461" ></A ><H2 >返回值</H2 ><P > Returns the square root as a string, or <TT CLASS="constant" ><B >NULL</B ></TT > if <CODE CLASS="parameter" >operand</CODE > is negative. </P ></DIV ><DIV CLASS="refsect1" ><A NAME="AEN14466" ></A ><H2 >范例</H2 ><TABLE WIDTH="100%" BORDER="0" CELLPADDING="0" CELLSPACING="0" CLASS="EXAMPLE" ><TR ><TD ><DIV CLASS="example" ><A NAME="AEN14468" ></A ><P ><B >例 1. <B CLASS="function" >bcsqrt()</B > example</B ></P ><TABLE BORDER="0" BGCOLOR="#E0E0E0" CELLPADDING="5" ><TR ><TD ><code><font color="#000000"> <font color="#0000BB"><?php<br /><br /></font><font color="#007700">echo </font><font color="#0000BB">bcsqrt</font><font color="#007700">(</font><font color="#DD0000">'2'</font><font color="#007700">, </font><font color="#0000BB">3</font><font color="#007700">); </font><font color="#FF8000">// 1.414<br /><br /></font><font color="#0000BB">?></font> </font> </code></TD ></TR ></TABLE ></DIV ></TD ></TR ></TABLE ></DIV ><DIV CLASS="refsect1" ><A NAME="AEN14472" ></A ><H2 >参见</H2 ><P > <P ></P ><TABLE BORDER="0" ><TBODY ><TR ><TD ><A HREF="function.bcpow.html" ><B CLASS="function" >bcpow()</B ></A ></TD ></TR ></TBODY ></TABLE ><P ></P > </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.bcscale.html" ACCESSKEY="P" >上一页</A ></TD ><TD WIDTH="34%" ALIGN="center" VALIGN="top" ><A HREF="index.html" ACCESSKEY="H" >起始页</A ></TD ><TD WIDTH="33%" ALIGN="right" VALIGN="top" ><A HREF="function.bcsub.html" ACCESSKEY="N" >下一页</A ></TD ></TR ><TR ><TD WIDTH="33%" ALIGN="left" VALIGN="top" >bcscale</TD ><TD WIDTH="34%" ALIGN="center" VALIGN="top" ><A HREF="ref.bc.html" ACCESSKEY="U" >上一级</A ></TD ><TD WIDTH="33%" ALIGN="right" VALIGN="top" >bcsub</TD ></TR ></TABLE ></DIV ></BODY ></HTML >