<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> <HTML ><HEAD ><TITLE >BC math 高精度数学函数</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="函数参考" HREF="funcref.html"><LINK REL="PREVIOUS" TITLE="aspell_suggest" HREF="function.aspell-suggest.html"><LINK REL="NEXT" TITLE="bcadd" HREF="function.bcadd.html"><META HTTP-EQUIV="Content-type" CONTENT="text/html; charset=UTF-8"></HEAD ><BODY CLASS="reference" 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.aspell-suggest.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.bcadd.html" ACCESSKEY="N" >下一页</A ></TD ></TR ></TABLE ><HR ALIGN="LEFT" WIDTH="100%"></DIV ><DIV CLASS="reference" ><A NAME="ref.bc" ></A ><DIV CLASS="TITLEPAGE" ><H1 CLASS="title" >VII. BC math 高精度数学函数</H1 ><DIV CLASS="PARTINTRO" ><A NAME="AEN13941" ></A ><DIV CLASS="section" ><H1 CLASS="section" ><A NAME="bc.intro" >简介</A ></H1 ><P > PHP 为任意精度数学计算提供了二进制计算器(Binary Calculator),它支持任意大小和精度的数字,以字符串形式描述。 </P ></DIV ><DIV CLASS="section" ><H1 CLASS="section" ><A NAME="bc.requirements" >需求</A ></H1 ><P > 自 PHP 4.0.4 以来,libbcmath 都绑定在 PHP 内部。本扩展不需要其它外部库的支持。 </P ></DIV ><DIV CLASS="section" ><H1 CLASS="section" ><A NAME="bc.installation" >安装</A ></H1 ><P > 本类函数仅在 PHP 编译时配置了 <CODE CLASS="option" >--enable-bcmath</CODE > 时可用。在 PHP 3 中,本类函数仅在 PHP 编译时<SPAN CLASS="emphasis" ><I CLASS="emphasis" >没有</I ></SPAN >配置 <CODE CLASS="option" >--disable-bcmath</CODE > 时可用。 </P ><P > <TT CLASS="literal" >PHP</TT > 的 Windows 版本已经内置该扩展模块的支持。无需加载任何附加扩展库即可使用这些函数。</P ></DIV ><DIV CLASS="section" ><H1 CLASS="section" ><A NAME="bc.configuration" >运行时配置</A ></H1 ><P >这些函数的行为受 <TT CLASS="filename" >php.ini</TT > 的影响。</P ><P > <DIV CLASS="table" ><A NAME="AEN13961" ></A ><P ><B >表 1. BC 数学库配置选项</B ></P ><TABLE BORDER="1" CLASS="CALSTABLE" ><COL><COL><COL><COL><THEAD ><TR ><TH >名称</TH ><TH >默认值</TH ><TH >可修改范围</TH ><TH >更新记录</TH ></TR ></THEAD ><TBODY ><TR ><TD >bcmath.scale</TD ><TD >"0"</TD ><TD >PHP_INI_ALL</TD ><TD > </TD ></TR ></TBODY ></TABLE ></DIV > 有关 PHP_INI_* 常量进一步的细节与定义参见<A HREF="ini.html" >附录 H</A >。 </P ><P >以下是配置选项的简要解释。</P ><P > <P ></P ><DIV CLASS="variablelist" ><DL ><DT ><A NAME="ini.bcmath.scale" ></A ><CODE CLASS="parameter" >bcmath.scale</CODE > <A HREF="language.types.integer.html" ><B CLASS="type" >integer</B ></A ></DT ><DD ><P > 所有 bcmath 函数中十进制数字的数目。参见 <A HREF="function.bcscale.html" ><B CLASS="function" >bcscale()</B ></A >。 </P ></DD ></DL ></DIV > </P ></DIV ><DIV CLASS="section" ><H1 CLASS="section" ><A NAME="bc.resources" >资源类型</A ></H1 ><P >本扩展模块未定义任何资源类型。</P ></DIV ><DIV CLASS="section" ><H1 CLASS="section" ><A NAME="bc.constants" >预定义常量</A ></H1 ><P >本扩展模块未定义任何常量。</P ></DIV ></DIV ><DIV CLASS="TOC" ><DL ><DT ><B >目录</B ></DT ><DT ><A HREF="function.bcadd.html" >bcadd</A > -- Add two arbitrary precision numbers</DT ><DT ><A HREF="function.bccomp.html" >bccomp</A > -- Compare two arbitrary precision numbers</DT ><DT ><A HREF="function.bcdiv.html" >bcdiv</A > -- Divide two arbitrary precision numbers</DT ><DT ><A HREF="function.bcmod.html" >bcmod</A > -- Get modulus of an arbitrary precision number</DT ><DT ><A HREF="function.bcmul.html" >bcmul</A > -- Multiply two arbitrary precision number</DT ><DT ><A HREF="function.bcpow.html" >bcpow</A > -- Raise an arbitrary precision number to another</DT ><DT ><A HREF="function.bcpowmod.html" >bcpowmod</A > -- Raise an arbitrary precision number to another, reduced by a specified modulus</DT ><DT ><A HREF="function.bcscale.html" >bcscale</A > -- Set default scale parameter for all bc math functions</DT ><DT ><A HREF="function.bcsqrt.html" >bcsqrt</A > -- Get the square root of an arbitrary precision number</DT ><DT ><A HREF="function.bcsub.html" >bcsub</A > -- Subtract one arbitrary precision number from another</DT ></DL ></DIV ></DIV ></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.aspell-suggest.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.bcadd.html" ACCESSKEY="N" >下一页</A ></TD ></TR ><TR ><TD WIDTH="33%" ALIGN="left" VALIGN="top" >aspell_suggest</TD ><TD WIDTH="34%" ALIGN="center" VALIGN="top" ><A HREF="funcref.html" ACCESSKEY="U" >上一级</A ></TD ><TD WIDTH="33%" ALIGN="right" VALIGN="top" >bcadd</TD ></TR ></TABLE ></DIV ></BODY ></HTML >