📄 ch11_1_3.htm
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<! Made by Html Translation Ver 1.0><html><head><title> 符号表示式的运算 </title></head><body BACKGROUND="../img1/bg0000.gif" tppabs="http://webclass.ncu.edu.tw/~junwu/img/bg0000.gif"><script language="JAVASCRIPT"><!--if (navigator.onLine){document.write("<!-- Spidersoft WebZIP Ad Banner Insert -->");document.write("<TABLE width=100% border=0 cellpadding=0 cellspacing=0>");document.write("<TR>");document.write("<TD>");document.write("<ILAYER id=ad1 visibility=hidden height=60></ILAYER>");document.write("<NOLAYER>");document.write("<IFRAME SRC='http://www.spidersoft.com/ads/bwz468_60.htm' width=100% height=60 marginwidth=0 marginheight=0 hspace=0 vspace=0 frameborder=0 scrolling=no></IFRAME>");document.write("</NOLAYER>");document.write("</TD>");document.write("</TR>");document.write("</TABLE>");document.write("<!-- End of Spidersoft WebZIP Ad Banner Insert-->");} //--></script><!-- Spidersoft WebZIP Ad Banner Insert --><!-- End of Spidersoft WebZIP Ad Banner Insert--><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><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><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><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><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><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><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><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><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><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><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><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><p>我们接著看几个应用上述函数的例子 </p><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><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><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><p><font COLOR="#FF0000" FACE="Times New Roman">>> symmul(p1,p3)</font> </p><p><font COLOR="#FF0000" FACE="Times New Roman">ans=</font> </p><p><font COLOR="#FF0000" FACE="Times New Roman">(y+4)*y</font> </p><p><font COLOR="#FF0000" FACE="Times New Roman">>> sympow(p2,3)</font> </p><p><font COLOR="#FF0000" FACE="Times New Roman">ans=</font> </p><p><font COLOR="#FF0000" FACE="Times New Roman">27*y^3/(y+2)^3</font> </p><p><font COLOR="#FF0000" FACE="Times New Roman">>> symadd(p1,p2)</font> </p><p><font COLOR="#FF0000" FACE="Times New Roman">ans=</font> </p><p><font COLOR="#FF0000" FACE="Times New Roman">1/(y-3)+3*y/(y+2)</font> </p><p><font COLOR="#FF0000" FACE="Times New Roman">>>[num,den] = numden(symadd(p1,p2))</font> </p><p><font COLOR="#FF0000" FACE="Times New Roman">ans=</font> </p><p><font COLOR="#FF0000" FACE="Times New Roman">[-8*y+2+3*y, (y-3)*(y+2)]</font> </p><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><p><font COLOR="#FF0000" FACE="Times New Roman">ans=</font> </p><p><font COLOR="#FF0000" FACE="Times New Roman">1+(-12+(1+y)*y)*y<br></font></p><hr><a HREF="ch11_1_2.htm" tppabs="http://webclass.ncu.edu.tw/~junwu/ch11_1_2.htm"><p><img SRC="../img1/lastpage.gif" tppabs="http://webclass.ncu.edu.tw/~junwu/img/lastpage.gif" BORDER="0" WIDTH="42" HEIGHT="42"></a> <a HREF="ch11_2.htm" tppabs="http://webclass.ncu.edu.tw/~junwu/ch11_2.htm"><img SRC="../img1/nextpage.gif" tppabs="http://webclass.ncu.edu.tw/~junwu/img/nextpage.gif" BORDER="0" HSPACE="10" WIDTH="42" HEIGHT="42"></a> <a HREF="../index.html" tppabs="http://webclass.ncu.edu.tw/~junwu/index.html"><img SRC="../img1/outline.gif" tppabs="http://webclass.ncu.edu.tw/~junwu/img/outline.gif" BORDER="0" HSPACE="6" WIDTH="42" HEIGHT="42"></a><br><font SIZE="2" COLOR="#AA55FF">上一页 下一页 讲义大纲 </font><layer src="http://www.spidersoft.com/ads/bwz468_60.htm" visibility="hidden" id="a1" width="600" onload="moveToAbsolute(ad1.pageX,ad1.pageY); 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