📄 ch11_1_3.htm
字号:
<! Made by Html Translation Ver 1.0>
<HTML>
<HEAD>
<TITLE> 符号表示式的运算 </TITLE>
</HEAD>
<BODY BACKGROUND="bg0000.gif" tppabs="http://166.111.167.223/computer/cai/matlabjc/img/bg0000.gif">
<FONT COLOR="#0000FF">
<H1>11.1.3 符号表示式的运算</H1>
</FONT>
<HR>
<P>
以下列出几个常用的符号运算函数，它们可以将一符号数学室转换成另一种型态。兹将分列如下：
<P>
<FONT COLOR=#FF0000 FACE="Times New Roman">horner(S)</FONT>
将<FONT COLOR=#FF0000 FACE="Times New Roman">S</FONT>转换成巢状表示式
<P>
<FONT COLOR=#FF0000 FACE="Times New Roman">numden(S)</FONT> 将<FONT COLOR=#FF0000 FACE="Times New Roman">S</FONT>的有理数表示成分子和分母的形式
<P>
<FONT COLOR=#FF0000 FACE="Times New Roman">numeric(S)</FONT>
将<FONT COLOR=#FF0000 FACE="Times New Roman">S</FONT>改成数值式<FONT FACE="Times New Roman">(</FONT><FONT COLOR=#FF0000 FACE="Times New Roman">S</FONT>不能含有任何符号变数<FONT FACE="Times New Roman">)</FONT>
<P>
<FONT COLOR=#FF0000 FACE="Times New Roman">poly2sym(c)</FONT>
转换多项式系数向量<FONT COLOR=#FF0000 FACE="Times New Roman">c</FONT>为符号多项式
<P>
<FONT COLOR=#FF0000 FACE="Times New Roman">pretty(S)</FONT>
将<FONT COLOR=#FF0000 FACE="Times New Roman">S</FONT>显示成数学式
<P>
<FONT COLOR=#FF0000 FACE="Times New Roman">sym2poly(S)</FONT>
转换<FONT COLOR=#FF0000 FACE="Times New Roman">S</FONT>为多项式系数向量
<P>
<FONT COLOR=#FF0000 FACE="Times New Roman">symadd(A,B)</FONT>
执行<FONT COLOR=#FF0000 FACE="Times New Roman">A+B</FONT>的符号加法
<P>
<FONT COLOR=#FF0000 FACE="Times New Roman">symdiv(A,B)</FONT>
执行<FONT COLOR=#FF0000 FACE="Times New Roman">A+B</FONT>的符号除法
<P>
<FONT COLOR=#FF0000 FACE="Times New Roman">symmul(A,B)</FONT>
执行<FONT COLOR=#FF0000 FACE="Times New Roman">A+B</FONT>的符号乘法
<P>
<FONT COLOR=#FF0000 FACE="Times New Roman">sympow(S,p)</FONT>
执行<FONT COLOR=#FF0000 FACE="Times New Roman">S^p</FONT>的符号次方运算
<P>
<FONT COLOR=#FF0000 FACE="Times New Roman">symsub(A,B)</FONT>
执行<FONT COLOR=#FF0000 FACE="Times New Roman">A+B</FONT>的符号减法
<BR>
<P>
我们接著看几个应用上述函数的例子
<P>
<FONT COLOR=#FF0000 FACE="Times New Roman">>>p1 = </FONT><FONT COLOR=#FF0000>'</FONT><FONT COLOR=#FF0000 FACE="Times New Roman">1/(y-3)</FONT><FONT COLOR=#FF0000>'</FONT><FONT COLOR=#FF0000 FACE="Times New Roman">;</FONT>
<P>
<FONT COLOR=#FF0000 FACE="Times New Roman">>>p2 = </FONT><FONT COLOR=#FF0000>'</FONT><FONT COLOR=#FF0000 FACE="Times New Roman">3*y/(y+2)</FONT><FONT COLOR=#FF0000>'</FONT><FONT COLOR=#FF0000 FACE="Times New Roman">;</FONT>
<P>
<FONT COLOR=#FF0000 FACE="Times New Roman">>>p3 = </FONT><FONT COLOR=#FF0000>'</FONT><FONT COLOR=#FF0000 FACE="Times New Roman">(y+4)*(y-3)*y</FONT><FONT COLOR=#FF0000>'</FONT><FONT COLOR=#FF0000 FACE="Times New Roman">;
<BR>
</FONT>
<P>
<FONT COLOR=#FF0000 FACE="Times New Roman">>> symmul(p1,p3)</FONT>
<P>
<FONT COLOR=#FF0000 FACE="Times New Roman">ans=</FONT>
<P>
<FONT COLOR=#FF0000 FACE="Times New Roman">(y+4)*y</FONT>
<P>
<FONT COLOR=#FF0000 FACE="Times New Roman">>> sympow(p2,3)</FONT>
<P>
<FONT COLOR=#FF0000 FACE="Times New Roman">ans=</FONT>
<P>
<FONT COLOR=#FF0000 FACE="Times New Roman">27*y^3/(y+2)^3</FONT>
<P>
<FONT COLOR=#FF0000 FACE="Times New Roman">>> symadd(p1,p2)</FONT>
<P>
<FONT COLOR=#FF0000 FACE="Times New Roman">ans=</FONT>
<P>
<FONT COLOR=#FF0000 FACE="Times New Roman">1/(y-3)+3*y/(y+2)</FONT>
<P>
<FONT COLOR=#FF0000 FACE="Times New Roman">>>[num,den] =
numden(symadd(p1,p2))</FONT>
<P>
<FONT COLOR=#FF0000 FACE="Times New Roman">ans=</FONT>
<P>
<FONT COLOR=#FF0000 FACE="Times New Roman">[-8*y+2+3*y, (y-3)*(y+2)]</FONT>
<P>
<FONT COLOR=#FF0000 FACE="Times New Roman">>> horner(symadd(p3,</FONT><FONT COLOR=#FF0000>'</FONT><FONT COLOR=#FF0000 FACE="Times New Roman">1</FONT><FONT COLOR=#FF0000>'</FONT><FONT COLOR=#FF0000 FACE="Times New Roman">)</FONT>
<P>
<FONT COLOR=#FF0000 FACE="Times New Roman">ans=</FONT>
<P>
<FONT COLOR=#FF0000 FACE="Times New Roman">1+(-12+(1+y)*y)*y<BR>
</FONT><HR>
<A HREF="ch11_1_2.htm" tppabs="http://166.111.167.223/computer/cai/matlabjc/ch11_1_2.htm"><IMG SRC="lastpage.gif" tppabs="http://166.111.167.223/computer/cai/matlabjc/img/lastpage.gif" BORDER=0></A>
<A HREF="ch11_2.htm" tppabs="http://166.111.167.223/computer/cai/matlabjc/ch11_2.htm"><IMG SRC="nextpage-1.gif" tppabs="http://166.111.167.223/computer/cai/matlabjc/img/nextpage.gif" BORDER=0 HSPACE=10></A>
<A HREF="index.html" tppabs="http://166.111.167.223/computer/cai/matlabjc/index.html"><IMG SRC="outline-1.gif" tppabs="http://166.111.167.223/computer/cai/matlabjc/img/outline.gif" BORDER=0 HSPACE=6></A><BR>
<FONT SIZE=2 COLOR=#AA55FF> 上一页 下一页 讲义大纲 </FONT>
</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 + -