第一节 mathematica快速入门.htm

Mathematica软件包的介绍

lang=EN-US><SPAN style="mso-spacerun: yes"><font size="4" face="楷体_GB2312">&nbsp;&nbsp;       
</font>                
</SPAN><font size="4" face="楷体_GB2312">我们可以通过运算符号“=”或“：=”来给一个变量赋值，一般格式为：</font></SPAN><font size="4" face="楷体_GB2312"><SPAN lang=EN-US                
style="FONT-FAMILY: 宋体; mso-hansi-font-family: 'Times New Roman'"><O:P>                
</O:P></SPAN></font></b></P>                
<P align=left class=MsoNormal                 
style="text-indent: 17.95pt; punctuation-wrap: simple; mso-line-break-override: restrictions; line-height: 200%"><b><SPAN                 
lang=EN-US><SPAN                 
style="mso-spacerun: yes"><font size="4" face="楷体_GB2312">&nbsp;</font></SPAN><font size="4" face="楷体_GB2312">变量=表达式<SPAN                
style="mso-spacerun: yes">&nbsp;&nbsp;&nbsp; </SPAN>或<SPAN                
style="mso-spacerun: yes">&nbsp;&nbsp;&nbsp;&nbsp;                
</SPAN>变量1=变量2=表达式</font></SPAN><font size="4" face="楷体_GB2312"><SPAN lang=EN-US                
style="FONT-FAMILY: 宋体; mso-hansi-font-family: 'Times New Roman'"><O:P>                
</O:P></SPAN></font></b></P>                
<P align=left class=MsoNormal                 
style="text-indent: 17.95pt; punctuation-wrap: simple; mso-line-break-override: restrictions; line-height: 200%"><b><font size="4" face="楷体_GB2312">其执行步骤为：先计算等号右侧的表达式的值，再将结果赋给左侧变量。如果使用“：<SPAN                
lang=EN-US>=”进行赋值，并不计算表达式的值，而是将整个表达是赋给变量，直到需要时才被计算。因此，“=”称为立即赋值，“：=”称为延迟赋值。例如：</SPAN><SPAN                
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style="FONT-FAMILY: 宋体; mso-hansi-font-family: 'Times New Roman'"><O:P>                
</O:P></SPAN></font></b></P>                
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lang=EN-US><b><font size="4" face="楷体_GB2312">In[8]:=Math4 = 3*2 + 6.8<O:P>                   
</O:P></font></b></SPAN></P>                  
<P align=left class=MsoNormal                  
style="text-indent: 17.95pt; punctuation-wrap: simple; mso-line-break-override: restrictions; line-height: 200%"><SPAN                  
lang=EN-US><b><font size="4" face="楷体_GB2312">Out[8]=12.8<O:P> </O:P></font></b></SPAN></P>                 
<P align=left class=MsoNormal                  
style="text-indent: 17.95pt; punctuation-wrap: simple; mso-line-break-override: restrictions; line-height: 200%"><SPAN                  
lang=EN-US><b><font size="4" face="楷体_GB2312">In[9]:=Math4 := 3*2 + 6.8<O:P>                  
</O:P></font></b></SPAN></P>                 
<P align=left class=MsoNormal                  
style="text-indent: 17.95pt; punctuation-wrap: simple; mso-line-break-override: restrictions; line-height: 200%"><b><font size="4" face="楷体_GB2312">注意：这一句没有输出<SPAN lang=EN-US                 
style="FONT-FAMILY: 宋体; mso-hansi-font-family: 'Times New Roman'"><O:P>                 
</O:P></SPAN></font></b></P>                 
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lang=EN-US><b><font size="4" face="楷体_GB2312">In[10]:=Math4 = 4x + 5x^2 + 2x^3 + 8x^4<O:P>                   
</O:P></font></b></SPAN></P>                  
<P align=left class=MsoNormal                  
style="text-indent: 17.95pt; punctuation-wrap: simple; mso-line-break-override: restrictions; line-height: 200%"><b><SPAN                  
lang=EN-US><font size="4" face="楷体_GB2312">Out[10]= <SPAN                  
style="mso-text-raise: -3.0pt"><!--[if gte vml 1]><V:SHAPE id=_x0000_i1031                  
style="HEIGHT: 15.75pt; WIDTH: 102pt" type="#_x0000_t75" o:ole=""><V:IMAGEDATA                  
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src="file:///C:/WINDOWS/TEMP/msoclip1/01/clip_image013.wmz"></V:SHAPE><![endif]--><IMG src="images/1.htm7.gif"                  
v:shapes="_x0000_i1031" width="136" height="21"></SPAN><!--[if gte mso 9]><xml>                 
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  DrawAspect="Content" ObjectID="_1048958862">                 
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 </font>                 
</SPAN><font size="4" face="楷体_GB2312"><SPAN lang=EN-US                 
style="FONT-FAMILY: 宋体; mso-hansi-font-family: 'Times New Roman'"><O:P></O:P></SPAN></font></b></P>                
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lang=EN-US><b><font size="4" face="楷体_GB2312">In[11]:=s1 = s2 = 3*4 + 4.5<O:P>                  
</O:P></font></b></SPAN></P>                 
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lang=EN-US><font size="4" face="楷体_GB2312">Out[11]=16.5</font></SPAN><font size="4" face="楷体_GB2312"><SPAN lang=EN-US                 
style="FONT-FAMILY: 宋体; mso-hansi-font-family: 'Times New Roman'"><O:P>                 
</O:P></SPAN></font></b></P>                 
<P align=left class=MsoNormal                  
style="text-indent: 17.95pt; punctuation-wrap: simple; mso-line-break-override: restrictions; line-height: 200%"><SPAN                  
lang=EN-US><b><font size="4" face="楷体_GB2312">In[12]:=Math4 /. x -&gt; 2<O:P>                  
</O:P></font></b></SPAN></P>                 
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style="text-indent: 17.95pt; punctuation-wrap: simple; mso-line-break-override: restrictions; line-height: 200%"><b><SPAN                  
lang=EN-US><font size="4" face="楷体_GB2312">Out[12]=172</font></SPAN><font size="4" face="楷体_GB2312"><SPAN lang=EN-US                 
style="FONT-FAMILY: 宋体; mso-hansi-font-family: 'Times New Roman'"><O:P>                 
</O:P></SPAN></font></b></P>                 
<P align=left class=MsoNormal                  
style="text-indent: 17.95pt; punctuation-wrap: simple; mso-line-break-override: restrictions; line-height: 200%"><b><font size="4" face="楷体_GB2312">其中“<SPAN                 
lang=EN-US>/.x-&gt;”为变换规则，他把变量Math4中的x变换为2。只要不进行重新赋值或退出系统，原有的变量就会保留。有时候我们需要清除这些值，以免在以后的计算中发生错误。清除变量Math4,s1如下：</SPAN><SPAN                 
lang=EN-US                 
style="FONT-FAMILY: 宋体; mso-hansi-font-family: 'Times New Roman'"><O:P>                 
</O:P></SPAN></font></b></P>                 
<P align=left class=MsoNormal                  
style="text-indent: 17.95pt; punctuation-wrap: simple; mso-line-break-override: restrictions; line-height: 200%"><SPAN                  
lang=EN-US><b><font size="4" face="楷体_GB2312">In[13]:=Math4 =.<O:P> </O:P></font></b></SPAN></P>                  
<P align=left class=MsoNormal                  
style="text-indent: 17.95pt; punctuation-wrap: simple; mso-line-break-override: restrictions; line-height: 200%"><SPAN                  
lang=EN-US><b><font size="4" face="楷体_GB2312">In[14]:=Clear[s1]<O:P> </O:P></font></b></SPAN></P>                 
<P align=left class=MsoNormal                  
style="text-indent: 17.95pt; punctuation-wrap: simple; mso-line-break-override: restrictions; line-height: 200%"><b><font size="4" face="楷体_GB2312">注意<SPAN lang=EN-US>:上述输入语句均没有输出。</SPAN><SPAN                 
lang=EN-US                 
style="FONT-FAMILY: 宋体; mso-hansi-font-family: 'Times New Roman'"><O:P>                 
&nbsp;</SPAN></font></b></P>                 
<P align=left class=MsoNormal                  
style="text-indent: 17.95pt; punctuation-wrap: simple; mso-line-break-override: restrictions; line-height: 200%">　</P>               
<p class="MsoNormal" style="margin-left:21.0pt;text-indent:-21.0pt;mso-list:l2 level1 lfo12;
tab-stops:list 21.0pt"><font color="#FF0000"><span style="font-style: normal; font-variant: normal; font-weight: normal; font-size: 7.0pt; font-family: Times New Roman" lang="EN-US">&nbsp;</span></font><b><SPAN               
lang=EN-US><font color="#FF0000">2．</font></SPAN></b><font color="#FF0000"><span style="font-style: normal; font-variant: normal; font-weight: normal; font-size: 7.0pt; font-family: Times New Roman" lang="EN-US">&nbsp;   
</span><span style="mso-ascii-font-family: Times New Roman; mso-hansi-font-family: Times New Roman"><font face="楷体_GB2312" size="4"><b>几个方便的输入方法</b></font></span></font></p> 
<p class="MsoNormal" style="text-indent: 17.95pt; punctuation-wrap: simple; mso-line-break-override: restrictions; line-height: 200%" align="left"><font color="#FF0000"><span lang="EN-US"><font face="楷体_GB2312" size="4"><b>(1)   
</b></font></span></font><font size="4"><b><font face="楷体_GB2312"><font color="#FF0000"><span style="mso-ascii-font-family: Times New Roman; mso-hansi-font-family: Times New Roman">调用</span>以</font><span style="mso-ascii-font-family: Times New Roman; mso-hansi-font-family: Times New Roman"><font color="#FF0000">前的计算结果，</font>有三种形式：</span></font></b></font></p> 
<div align="center"> 
  <table border="1" cellspacing="0" cellpadding="0" style="border-collapse: collapse; mso-table-layout-alt: fixed; mso-border-alt: solid windowtext .5pt; mso-padding-alt: 0cm 5.4pt 0cm 5.4pt; border-style: none; border-width: medium" width="543"> 
    <tr style="height:17.25pt"> 
      <td width="128" style="height: 17.25pt; border: .5pt solid windowtext; padding-left: 5.4pt; padding-right: 5.4pt; padding-top: 0cm; padding-bottom: 0cm"> 
        <p class="MsoNormal" align="center" style="text-align:center"><span style="mso-ascii-font-family: Times New Roman; mso-hansi-font-family: Times New Roman"><font face="楷体_GB2312" size="4"><b>％</b></font></span></p> 
      </td> 
      <td width="384" style="mso-border-left-alt: solid windowtext .5pt; height: 17.25pt; border-left-style: none; border-left-width: medium; border-right: .5pt solid windowtext; border-top: .5pt solid windowtext; border-bottom: .5pt solid windowtext; padding-left: 5.4pt; padding-right: 5.4pt; padding-top: 0cm; padding-bottom: 0cm"> 
        <p class="MsoNormal" align="center" style="text-align:center"><span style="mso-ascii-font-family: Times New Roman; mso-hansi-font-family: Times New Roman"><font face="楷体_GB2312" size="4"><b>表示用上一次的结果</b></font></span></p> 
      </td> 
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    <tr style="height:17.25pt"> 
      <td width="128" style="mso-border-top-alt: solid windowtext .5pt; height: 17.25pt; border-left: .5pt solid windowtext; border-right: .5pt solid windowtext; border-top-style: none; border-top-width: medium; border-bottom: .5pt solid windowtext; padding-left: 5.4pt; padding-right: 5.4pt; padding-top: 0cm; padding-bottom: 0cm"> 
        <p class="MsoNormal" align="center" style="text-align:center"><span style="mso-ascii-font-family: Times New Roman; mso-hansi-font-family: Times New Roman"><font face="楷体_GB2312" size="4"><b>％％</b></font></span></p> 
      </td> 
      <td width="384" style="mso-border-top-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; height: 17.25pt; border-left-style: none; border-left-width: medium; border-right: .5pt solid windowtext; border-top-style: none; border-top-width: medium; border-bottom: .5pt solid windowtext; padding-left: 5.4pt; padding-right: 5.4pt; padding-top: 0cm; padding-bottom: 0cm"> 
        <p class="MsoNormal" align="center" style="text-align:center"><span style="mso-ascii-font-family: Times New Roman; mso-hansi-font-family: Times New Roman"><font face="楷体_GB2312" size="4"><b>表示用上面倒数第二个输出结果</b></font></span></p> 
      </td> 
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      <td width="128" style="mso-border-top-alt: solid windowtext .5pt; height: 17.25pt; border-left: .5pt solid windowtext; border-right: .5pt solid windowtext; border-top-style: none; border-top-width: medium; border-bottom: .5pt solid windowtext; padding-left: 5.4pt; padding-right: 5.4pt; padding-top: 0cm; padding-bottom: 0cm"> 
        <p class="MsoNormal" al