第六节 mathematica编程基础.htm

Mathematica软件包的介绍

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      style="FONT-FAMILY: 宋体; mso-hansi-font-family: 'Times New Roman'; mso-ascii-font-family: 'Times New Roman'"><font size="4"><b>命令格式</b></font></SPAN></P></TD>     
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      style="FONT-FAMILY: 宋体; mso-hansi-font-family: 'Times New Roman'; mso-ascii-font-family: 'Times New Roman'"><font size="4"><b>含义</b></font></SPAN></P></TD></TR>     
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      lang=EN-US><font size="4"><b>lhs:=rhs/;test</b></font></SPAN></P></TD>     
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      style="FONT-FAMILY: 宋体; mso-hansi-font-family: 'Times New Roman'; mso-ascii-font-family: 'Times New Roman'"><b><font size="4">当</font></b></SPAN><b><font size="4"><SPAN      
      lang=EN-US>test</SPAN><SPAN      
      style="FONT-FAMILY: 宋体; mso-hansi-font-family: 'Times New Roman'; mso-ascii-font-family: 'Times New Roman'">为真时使用定义</SPAN></font></b></P></TD></TR>     
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      lang=EN-US><font size="4"><b>If[test,then]</b></font></SPAN></P></TD>     
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      style="FONT-FAMILY: 宋体; mso-hansi-font-family: 'Times New Roman'; mso-ascii-font-family: 'Times New Roman'"><b><font size="4">若</font></b></SPAN><b><font size="4"><SPAN      
      lang=EN-US>test</SPAN><SPAN      
      style="FONT-FAMILY: 宋体; mso-hansi-font-family: 'Times New Roman'; mso-ascii-font-family: 'Times New Roman'">成立执行</SPAN><SPAN      
      lang=EN-US>then</SPAN><SPAN      
      style="FONT-FAMILY: 宋体; mso-hansi-font-family: 'Times New Roman'; mso-ascii-font-family: 'Times New Roman'">部分，不成立执行下一语句</SPAN></font></b></P></TD></TR>     
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      lang=EN-US><font size="4"><b>If[test,then,else]</b></font></SPAN></P></TD>     
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      style="FONT-FAMILY: 宋体; mso-hansi-font-family: 'Times New Roman'; mso-ascii-font-family: 'Times New Roman'"><b><font size="4">若</font></b></SPAN><b><font size="4"><SPAN      
      lang=EN-US>test</SPAN><SPAN      
      style="FONT-FAMILY: 宋体; mso-hansi-font-family: 'Times New Roman'; mso-ascii-font-family: 'Times New Roman'">成立执行</SPAN><SPAN      
      lang=EN-US>then</SPAN><SPAN      
      style="FONT-FAMILY: 宋体; mso-hansi-font-family: 'Times New Roman'; mso-ascii-font-family: 'Times New Roman'">部分，否则执行</SPAN><SPAN      
      lang=EN-US>else</SPAN><SPAN      
      style="FONT-FAMILY: 宋体; mso-hansi-font-family: 'Times New Roman'; mso-ascii-font-family: 'Times New Roman'">部分</SPAN></font></b></P></TD></TR>     
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      lang=EN-US><font size="4"><b>Which[test1,value1, test2,value2,…]</b></font></SPAN></P></TD>        
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      style="FONT-FAMILY: 宋体; mso-hansi-font-family: 'Times New Roman'; mso-ascii-font-family: 'Times New Roman'"><b><font size="4">依次计算</font></b></SPAN><b><font size="4"><SPAN        
      lang=EN-US>testi</SPAN><SPAN        
      style="FONT-FAMILY: 宋体; mso-hansi-font-family: 'Times New Roman'; mso-ascii-font-family: 'Times New Roman'">，只计算第一个为</SPAN><SPAN        
      lang=EN-US>True</SPAN><SPAN        
      style="FONT-FAMILY: 宋体; mso-hansi-font-family: 'Times New Roman'; mso-ascii-font-family: 'Times New Roman'">的</SPAN><SPAN        
      lang=EN-US>valuei</SPAN><SPAN        
      style="FONT-FAMILY: 宋体; mso-hansi-font-family: 'Times New Roman'; mso-ascii-font-family: 'Times New Roman'">表达式</SPAN></font></b></P></TD></TR>       
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      lang=EN-US><font size="4"><b>Switch[expr,form1,value1, form2,value2,…]</b></font></SPAN></P></TD>        
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      <P class=MsoNormal style="text-indent: 17.95pt; line-height: 200%"><SPAN         
      style="FONT-FAMILY: 宋体; mso-hansi-font-family: 'Times New Roman'; mso-ascii-font-family: 'Times New Roman'"><b><font size="4">计算</font></b></SPAN><b><font size="4"><SPAN        
      lang=EN-US>expr</SPAN><SPAN        
      style="FONT-FAMILY: 宋体; mso-hansi-font-family: 'Times New Roman'; mso-ascii-font-family: 'Times New Roman'">，找到与</SPAN><SPAN        
      lang=EN-US>expr</SPAN><SPAN        
      style="FONT-FAMILY: 宋体; mso-hansi-font-family: 'Times New Roman'; mso-ascii-font-family: 'Times New Roman'">相等的</SPAN><SPAN        
      lang=EN-US>formi</SPAN><SPAN        
      style="FONT-FAMILY: 宋体; mso-hansi-font-family: 'Times New Roman'; mso-ascii-font-family: 'Times New Roman'">值，执行相应的</SPAN><SPAN        
      lang=EN-US>valuei</SPAN><SPAN        
      style="FONT-FAMILY: 宋体; mso-hansi-font-family: 'Times New Roman'; mso-ascii-font-family: 'Times New Roman'">表达式</SPAN></font></b></P></TD></TR></TBODY></TABLE>       
<P class=MsoNormal style="text-indent: 17.95pt; line-height: 200%"><font size="4"><b><SPAN        
style="FONT-FAMILY: 宋体; mso-hansi-font-family: 'Times New Roman'; mso-ascii-font-family: 'Times New Roman'">以下我们着重讲解</SPAN><SPAN        
lang=EN-US>If</SPAN><SPAN        
style="FONT-FAMILY: 宋体; mso-hansi-font-family: 'Times New Roman'; mso-ascii-font-family: 'Times New Roman'">和</SPAN><SPAN        
lang=EN-US>Which</SPAN><SPAN        
style="FONT-FAMILY: 宋体; mso-hansi-font-family: 'Times New Roman'; mso-ascii-font-family: 'Times New Roman'">语句。</SPAN><SPAN        
lang=EN-US>If</SPAN><SPAN        
style="FONT-FAMILY: 宋体; mso-hansi-font-family: 'Times New Roman'; mso-ascii-font-family: 'Times New Roman'">构造了一种二路分支选择结构。这是一种最基本的选择结构。他首先对条件表达式进行判断，若条件为</SPAN><SPAN        
lang=EN-US>True</SPAN><SPAN        
style="FONT-FAMILY: 宋体; mso-hansi-font-family: 'Times New Roman'; mso-ascii-font-family: 'Times New Roman'">（成立），就执行</SPAN><SPAN        
lang=EN-US>then</SPAN><SPAN        
style="FONT-FAMILY: 宋体; mso-hansi-font-family: 'Times New Roman'; mso-ascii-font-family: 'Times New Roman'">部分，否则执行</SPAN><SPAN        
lang=EN-US>else</SPAN><SPAN        
style="FONT-FAMILY: 宋体; mso-hansi-font-family: 'Times New Roman'; mso-ascii-font-family: 'Times New Roman'">部分。下面给出一个具有两个条件的选择分支</SPAN><SPAN        
lang=EN-US>:</SPAN></b></font></P>       
<P class=MsoNormal style="tab-stops: 0cm; line-height: 200%"><SPAN        
style="FONT-FAMILY: 宋体; mso-hansi-font-family: 'Times New Roman'; mso-ascii-font-family: 'Times New Roman'"><b><font size="4">例</font></b></SPAN><b><font size="4"><SPAN        
lang=EN-US>2.</SPAN><SPAN        
style="FONT-FAMILY: 宋体; mso-hansi-font-family: 'Times New Roman'; mso-ascii-font-family: 'Times New Roman'">求一个数的绝对值</SPAN><SPAN        
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