📄 ch02_16.htm
字号:
<HTML><HEAD><TITLE>Recipe 2.15. Using Complex Numbers (Perl Cookbook)</TITLE><METANAME="DC.title"CONTENT="Perl Cookbook"><METANAME="DC.creator"CONTENT="Tom Christiansen & Nathan Torkington"><METANAME="DC.publisher"CONTENT="O'Reilly & Associates, Inc."><METANAME="DC.date"CONTENT="1999-07-02T01:30:21Z"><METANAME="DC.type"CONTENT="Text.Monograph"><METANAME="DC.format"CONTENT="text/html"SCHEME="MIME"><METANAME="DC.source"CONTENT="1-56592-243-3"SCHEME="ISBN"><METANAME="DC.language"CONTENT="en-US"><METANAME="generator"CONTENT="Jade 1.1/O'Reilly DocBook 3.0 to HTML 4.0"><LINKREV="made"HREF="mailto:online-books@oreilly.com"TITLE="Online Books Comments"><LINKREL="up"HREF="ch02_01.htm"TITLE="2. Numbers"><LINKREL="prev"HREF="ch02_15.htm"TITLE="2.14. Multiplying Matrices"><LINKREL="next"HREF="ch02_17.htm"TITLE="2.16. Converting Between Octal and Hexadecimal"></HEAD><BODYBGCOLOR="#FFFFFF"><img alt="Book Home" border="0" src="gifs/smbanner.gif" usemap="#banner-map" /><map name="banner-map"><area shape="rect" coords="1,-2,616,66" href="index.htm" alt="Perl Cookbook"><area shape="rect" coords="629,-11,726,25" href="jobjects/fsearch.htm" alt="Search this book" /></map><div class="navbar"><p><TABLEWIDTH="684"BORDER="0"CELLSPACING="0"CELLPADDING="0"><TR><TDALIGN="LEFT"VALIGN="TOP"WIDTH="228"><ACLASS="sect1"HREF="ch02_15.htm"TITLE="2.14. Multiplying Matrices"><IMGSRC="../gifs/txtpreva.gif"ALT="Previous: 2.14. Multiplying Matrices"BORDER="0"></A></TD><TDALIGN="CENTER"VALIGN="TOP"WIDTH="228"><B><FONTFACE="ARIEL,HELVETICA,HELV,SANSERIF"SIZE="-1"><ACLASS="chapter"REL="up"HREF="ch02_01.htm"TITLE="2. Numbers"></A></FONT></B></TD><TDALIGN="RIGHT"VALIGN="TOP"WIDTH="228"><ACLASS="sect1"HREF="ch02_17.htm"TITLE="2.16. Converting Between Octal and Hexadecimal"><IMGSRC="../gifs/txtnexta.gif"ALT="Next: 2.16. Converting Between Octal and Hexadecimal"BORDER="0"></A></TD></TR></TABLE></DIV><DIVCLASS="sect1"><H2CLASS="sect1"><ACLASS="title"NAME="ch02-15835">2.15. Using Complex Numbers</A></H2><DIVCLASS="sect2"><H3CLASS="sect2"><ACLASS="title"NAME="ch02-pgfId-1161">Problem <ACLASS="indexterm"NAME="ch02-idx-1000008098-0"></A><ACLASS="indexterm"NAME="ch02-idx-1000008098-1"></A><ACLASS="indexterm"NAME="ch02-idx-1000008098-2"></A><ACLASS="indexterm"NAME="ch02-idx-1000008098-3"></A><ACLASS="indexterm"NAME="ch02-idx-1000008098-4"></A></A></H3><PCLASS="para">Your application must manipulate complex numbers, as are often needed in engineering, science, and mathematics.</P></DIV><DIVCLASS="sect2"><H3CLASS="sect2"><ACLASS="title"NAME="ch02-pgfId-1167">Solution</A></H3><PCLASS="para">Either keep track of the real and imaginary components yourself, or use the Math::Complex class (part of the standard Perl distribution).</P><DIVCLASS="sect3"><H4CLASS="sect3"><ACLASS="title"NAME="ch02-pgfId-1000005642">Manually</A></H4><PRECLASS="programlisting"># $c = $a * $b manually$c_real = ( $a_real * $b_real ) - ( $a_imaginary * $b_imaginary );$c_imaginary = ( $a_real * $b_imaginary ) + ( $b_real * $a_imaginary );</PRE></DIV><DIVCLASS="sect3"><H4CLASS="sect3"><ACLASS="title"NAME="ch02-pgfId-1000005646">Math::Complex</A></H4><PRECLASS="programlisting"># $c = $a * $b using Math::Complexuse Math::Complex;$c = $a * $b;</PRE></DIV></DIV><DIVCLASS="sect2"><H3CLASS="sect2"><ACLASS="title"NAME="ch02-pgfId-1173">Discussion</A></H3><PCLASS="para">Here's how you'd manually multiply <CODECLASS="literal">3+5i</CODE> and <CODECLASS="literal">2-2i</CODE>:</P><PRECLASS="programlisting">$a_real = 3; $a_imaginary = 5; # 3 + 5i;$b_real = 2; $b_imaginary = -2; # 2 - 2i;$c_real = ( $a_real * $b_real ) - ( $a_imaginary * $b_imaginary );$c_imaginary = ( $a_real * $b_imaginary ) + ( $b_real * $a_imaginary );print "c = ${c_real}+${c_imaginary}i\n";<CODECLASS="userinput"><B><CODECLASS="replaceable"><I>c = 16+4i</I></CODE></B></CODE></PRE><PCLASS="para">and with Math::Complex:</P><PRECLASS="programlisting">use Math::Complex;$a = Math::Complex->new(3,5); # or Math::Complex->new(3,5);$b = Math::Complex->new(2,-2);$c = $a * $b;print "c = $c\n";<CODECLASS="userinput"><B><CODECLASS="replaceable"><I>c = 16+4i</I></CODE></B></CODE></PRE><PCLASS="para">With the 5.004 version, you may create complex numbers via the <CODECLASS="literal">cplx</CODE> constructor or via the exported constant <EMCLASS="emphasis">i</EM> :</P><PRECLASS="programlisting">use Math::Complex;$c = cplx(3,5) * cplx(2,-2); # easier on the eye$d = 3 + 4*i; # 3 + 4iprintf "sqrt($d) = %s\n", sqrt($d);<CODECLASS="userinput"><B><CODECLASS="replaceable"><I>sqrt(3+4i) = 2+i</I></CODE></B></CODE></PRE><PCLASS="para">The original Math::Complex module distributed with 5.003 did not overload as many functions and operators as the 5.004 version does. Also, the Math::Trig module (new as of 5.004) uses the Math::Complex module internally because some functions can break out from the real axis into the complex plane - for example, the inverse sine of 2.</P></DIV><DIVCLASS="sect2"><H3CLASS="sect2"><ACLASS="title"NAME="ch02-pgfId-1225">See Also</A></H3><PCLASS="para">The documentation for the standard Math::Complex module (also in <ACLASS="olink"HREF="../prog/ch07_01.htm">Chapter 7</A> of <ACLASS="citetitle"HREF="../prog/index.htm"TITLE="Programming Perl"><CITECLASS="citetitle">Programming Perl</CITE></A>)<ACLASS="indexterm"NAME="ch02-idx-1000008100-0"></A><ACLASS="indexterm"NAME="ch02-idx-1000008100-1"></A><ACLASS="indexterm"NAME="ch02-idx-1000008100-2"></A><ACLASS="indexterm"NAME="ch02-idx-1000008100-3"></A><ACLASS="indexterm"NAME="ch02-idx-1000008100-4"></A></P></DIV></DIV><DIVCLASS="htmlnav"><P></P><HRALIGN="LEFT"WIDTH="684"TITLE="footer"><TABLEWIDTH="684"BORDER="0"CELLSPACING="0"CELLPADDING="0"><TR><TDALIGN="LEFT"VALIGN="TOP"WIDTH="228"><ACLASS="sect1"HREF="ch02_15.htm"TITLE="2.14. Multiplying Matrices"><IMGSRC="../gifs/txtpreva.gif"ALT="Previous: 2.14. Multiplying Matrices"BORDER="0"></A></TD><TDALIGN="CENTER"VALIGN="TOP"WIDTH="228"><ACLASS="book"HREF="index.htm"TITLE="Perl Cookbook"><IMGSRC="../gifs/txthome.gif"ALT="Perl Cookbook"BORDER="0"></A></TD><TDALIGN="RIGHT"VALIGN="TOP"WIDTH="228"><ACLASS="sect1"HREF="ch02_17.htm"TITLE="2.16. Converting Between Octal and Hexadecimal"><IMGSRC="../gifs/txtnexta.gif"ALT="Next: 2.16. Converting Between Octal and Hexadecimal"BORDER="0"></A></TD></TR><TR><TDALIGN="LEFT"VALIGN="TOP"WIDTH="228">2.14. Multiplying Matrices</TD><TDALIGN="CENTER"VALIGN="TOP"WIDTH="228"><ACLASS="index"HREF="index/index.htm"TITLE="Book Index"><IMGSRC="../gifs/index.gif"ALT="Book Index"BORDER="0"></A></TD><TDALIGN="RIGHT"VALIGN="TOP"WIDTH="228">2.16. Converting Between Octal and Hexadecimal</TD></TR></TABLE><HRALIGN="LEFT"WIDTH="684"TITLE="footer"><FONTSIZE="-1"></DIV<!-- LIBRARY NAV BAR --> <img src="../gifs/smnavbar.gif" usemap="#library-map" border="0" alt="Library Navigation Links"><p> <a href="copyrght.htm">Copyright © 2002</a> O'Reilly & Associates. All rights reserved.</font> </p> <map name="library-map"> <area shape="rect" coords="1,0,85,94" href="../index.htm"><area shape="rect" coords="86,1,178,103" href="../lwp/index.htm"><area shape="rect" coords="180,0,265,103" href="../lperl/index.htm"><area shape="rect" coords="267,0,353,105" href="../perlnut/index.htm"><area shape="rect" coords="354,1,446,115" href="../prog/index.htm"><area shape="rect" coords="448,0,526,132" href="../tk/index.htm"><area shape="rect" coords="528,1,615,119" href="../cookbook/index.htm"><area shape="rect" coords="617,0,690,135" href="../pxml/index.htm"></map> </BODY></HTML>⌨️ 快捷键说明
复制代码
Ctrl + C
搜索代码
Ctrl + F
全屏模式
F11
切换主题
Ctrl + Shift + D
显示快捷键
?
增大字号
Ctrl + =
减小字号
Ctrl + -