📄 第六节 mathematica编程基础.htm
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<P class=MsoNormal style="text-indent: 17.95pt; mso-list: skip; 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">判定</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'">是否成立，成立输出</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'">否则输出</SPAN><SPAN
lang=EN-US>False</SPAN></font></b></P></TD></TR></TBODY></TABLE>
<P align=left class=MsoNormal
style="text-indent: 17.95pt; mso-list: skip; line-height: 200%"><SPAN
style="FONT-FAMILY: 宋体; mso-hansi-font-family: 'Times New Roman'; mso-font-kerning: 0pt"><font size="4"><b>其他的逻辑运算符有：<SPAN
lang=EN-US> >, >=, <, <=, !（非）, True(真)，False(假)<O:P>
</O:P></SPAN></b></font></SPAN></P>
<P align=left class=MsoNormal
style="text-indent: 17.95pt; mso-list: skip; line-height: 200%"><SPAN
style="FONT-FAMILY: 宋体; mso-hansi-font-family: 'Times New Roman'; mso-font-kerning: 0pt"><font size="4"><b>逻辑运算的结果为真（成立）或假（不成立）。如：<SPAN
lang=EN-US>2.3==2.4(运算结果为假False)，2.3<2.4(运算结果为真True)。<O:P>
</O:P></SPAN></b></font></SPAN></P>
<P align=left class=MsoNormal
style="text-indent: 17.95pt; mso-list: skip; line-height: 200%"><SPAN
style="FONT-FAMILY: 宋体; mso-hansi-font-family: 'Times New Roman'; mso-font-kerning: 0pt"><font size="4"><b>例<SPAN
lang=EN-US>1 判定下列结果的值：<O:P> </O:P></SPAN></b></font></SPAN></P>
<P class=MsoNormal style="text-indent: 20.5pt; mso-list: skip; 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; mso-bidi-font-size: 10.0pt">（</SPAN><SPAN
lang=EN-US style="mso-bidi-font-size: 10.0pt">1</SPAN><SPAN
style="font-family: 宋体; mso-hansi-font-family: Times New Roman; mso-ascii-font-family: Times New Roman; mso-bidi-font-size: 10.0pt">）</SPAN><SPAN
lang=EN-US style="mso-bidi-font-size: 10.0pt">10 < 7<SPAN
style="mso-spacerun: yes">
</SPAN></SPAN><SPAN
style="font-family: 宋体; mso-hansi-font-family: Times New Roman; mso-ascii-font-family: Times New Roman; mso-bidi-font-size: 10.0pt">（</SPAN><SPAN
lang=EN-US style="mso-bidi-font-size: 10.0pt">2</SPAN><SPAN
style="font-family: 宋体; mso-hansi-font-family: Times New Roman; mso-ascii-font-family: Times New Roman; mso-bidi-font-size: 10.0pt">）</SPAN><SPAN
lang=EN-US style="mso-bidi-font-size: 10.0pt">3 < 5 <=
6<SPAN style="mso-spacerun: yes"> </SPAN></SPAN><SPAN
style="font-family: 宋体; mso-hansi-font-family: Times New Roman; mso-ascii-font-family: Times New Roman; mso-bidi-font-size: 10.0pt">（</SPAN><SPAN
lang=EN-US style="mso-bidi-font-size: 10.0pt">3</SPAN><SPAN
style="font-family: 宋体; mso-hansi-font-family: Times New Roman; mso-ascii-font-family: Times New Roman; mso-bidi-font-size: 10.0pt">）</SPAN><SPAN
lang=EN-US style="mso-bidi-font-size: 10.0pt">3 != 2 != 3<SPAN
style="mso-spacerun: yes"> </SPAN></SPAN><SPAN
style="font-family: 宋体; mso-hansi-font-family: Times New Roman; mso-ascii-font-family: Times New Roman; mso-bidi-font-size: 10.0pt">（</SPAN><SPAN
lang=EN-US style="mso-bidi-font-size: 10.0pt">4</SPAN><SPAN
style="font-family: 宋体; mso-hansi-font-family: Times New Roman; mso-ascii-font-family: Times New Roman; mso-bidi-font-size: 10.0pt">）</SPAN><SPAN
lang=EN-US style="mso-bidi-font-size: 10.0pt">7 > 4
&& 2 != 3<O:P> </O:P></SPAN></b></font></P>
<P class=MsoNormal style="text-indent: 20.5pt; mso-list: skip; 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; mso-bidi-font-size: 10.0pt">（</SPAN><SPAN
lang=EN-US style="mso-bidi-font-size: 10.0pt">5</SPAN><SPAN
style="font-family: 宋体; mso-hansi-font-family: Times New Roman; mso-ascii-font-family: Times New Roman; mso-bidi-font-size: 10.0pt">）</SPAN><SPAN
lang=EN-US style="mso-bidi-font-size: 10.0pt">x > y<SPAN
style="mso-spacerun: yes">
</SPAN></SPAN><SPAN
style="font-family: 宋体; mso-hansi-font-family: Times New Roman; mso-ascii-font-family: Times New Roman; mso-bidi-font-size: 10.0pt">（</SPAN><SPAN
lang=EN-US style="mso-bidi-font-size: 10.0pt">6</SPAN><SPAN
style="font-family: 宋体; mso-hansi-font-family: Times New Roman; mso-ascii-font-family: Times New Roman; mso-bidi-font-size: 10.0pt">）</SPAN><SPAN
lang=EN-US style="mso-bidi-font-size: 10.0pt">(p || q)
&& !(r || s)<O:P> </O:P></SPAN></b></font></P>
<P class=MsoNormal style="text-indent: 20.5pt; mso-list: skip; 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; mso-bidi-font-size: 10.0pt">解：（</SPAN><SPAN
lang=EN-US style="mso-bidi-font-size: 10.0pt">1</SPAN><SPAN
style="font-family: 宋体; mso-hansi-font-family: Times New Roman; mso-ascii-font-family: Times New Roman; mso-bidi-font-size: 10.0pt">）</SPAN><SPAN
lang=EN-US style="mso-bidi-font-size: 10.0pt">False<SPAN
style="mso-spacerun: yes"> </SPAN></SPAN><SPAN
style="font-family: 宋体; mso-hansi-font-family: Times New Roman; mso-ascii-font-family: Times New Roman; mso-bidi-font-size: 10.0pt">（</SPAN><SPAN
lang=EN-US style="mso-bidi-font-size: 10.0pt">2</SPAN><SPAN
style="font-family: 宋体; mso-hansi-font-family: Times New Roman; mso-ascii-font-family: Times New Roman; mso-bidi-font-size: 10.0pt">）</SPAN><SPAN
lang=EN-US style="mso-bidi-font-size: 10.0pt">True<SPAN
style="mso-spacerun: yes"> </SPAN></SPAN><SPAN
style="font-family: 宋体; mso-hansi-font-family: Times New Roman; mso-ascii-font-family: Times New Roman; mso-bidi-font-size: 10.0pt">（</SPAN><SPAN
lang=EN-US style="mso-bidi-font-size: 10.0pt">3</SPAN><SPAN
style="font-family: 宋体; mso-hansi-font-family: Times New Roman; mso-ascii-font-family: Times New Roman; mso-bidi-font-size: 10.0pt">）</SPAN><SPAN
lang=EN-US style="mso-bidi-font-size: 10.0pt">False<SPAN
style="mso-spacerun: yes"> </SPAN></SPAN><SPAN
style="font-family: 宋体; mso-hansi-font-family: Times New Roman; mso-ascii-font-family: Times New Roman; mso-bidi-font-size: 10.0pt">（</SPAN><SPAN
lang=EN-US style="mso-bidi-font-size: 10.0pt">4</SPAN><SPAN
style="font-family: 宋体; mso-hansi-font-family: Times New Roman; mso-ascii-font-family: Times New Roman; mso-bidi-font-size: 10.0pt">）</SPAN><SPAN
lang=EN-US style="mso-bidi-font-size: 10.0pt">True<O:P>
</O:P></SPAN></b></font></P>
<P class=MsoNormal style="text-indent: 20.5pt; mso-list: skip; 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; mso-bidi-font-size: 10.0pt">（</SPAN><SPAN
lang=EN-US style="mso-bidi-font-size: 10.0pt">5</SPAN><SPAN
style="font-family: 宋体; mso-hansi-font-family: Times New Roman; mso-ascii-font-family: Times New Roman; mso-bidi-font-size: 10.0pt">）计算机不知道</SPAN><SPAN
lang=EN-US style="mso-bidi-font-size: 10.0pt">x,y</SPAN><SPAN
style="font-family: 宋体; mso-hansi-font-family: Times New Roman; mso-ascii-font-family: Times New Roman; mso-bidi-font-size: 10.0pt">的值，原样输出：</SPAN><SPAN
lang=EN-US style="mso-bidi-font-size: 10.0pt">x > y<SPAN
style="mso-spacerun: yes">
</SPAN></SPAN><SPAN
style="font-family: 宋体; mso-hansi-font-family: Times New Roman; mso-ascii-font-family: Times New Roman; mso-bidi-font-size: 10.0pt">（</SPAN><SPAN
lang=EN-US style="mso-bidi-font-size: 10.0pt">6</SPAN><SPAN
style="font-family: 宋体; mso-hansi-font-family: Times New Roman; mso-ascii-font-family: Times New Roman; mso-bidi-font-size: 10.0pt">）计算机不知道</SPAN><SPAN
lang=EN-US
style="mso-bidi-font-size: 10.0pt">p,q,r,s</SPAN><SPAN
style="font-family: 宋体; mso-hansi-font-family: Times New Roman; mso-ascii-font-family: Times New Roman; mso-bidi-font-size: 10.0pt">的值，原样输出：</SPAN><SPAN
lang=EN-US style="mso-bidi-font-size: 10.0pt">(p || q)
&& !(r || s)<O:P> </SPAN></b></font></P>
<P class=MsoNormal style="text-indent: 20.5pt; mso-list: skip; line-height: 200%"><font size="4"><b><SPAN
lang=EN-US style="mso-bidi-font-size: 10.0pt"> </O:P></SPAN></b></font></P>
<P class=MsoNormal style="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 color="#FF0000" size="5">二、<a name="顺序结构">顺序结构</a></font></b></SPAN></P>
<P class=MsoNormal style="text-indent: 17.95pt; mso-list: skip; 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'">在</SPAN><SPAN
lang=EN-US>Mathematica</SPAN><SPAN
style="FONT-FAMILY: 宋体; mso-hansi-font-family: 'Times New Roman'; mso-ascii-font-family: 'Times New Roman'">系统中，顺序结构实际上就是一系列表达式的组合。<font color="#FF0000">在一个表达式后跟一个分号</font>，接着再写一个表达式，就构成了顺序结构。顺序结构中的语句具有并列关系，且以后面的语句结果为他们顺序执行后的最终结果。计算机在执行时按照你书写的顺序一句一句执行。但是带分号的语句是不会输出</SPAN><SPAN
lang=EN-US>Out</SPAN><SPAN
style="FONT-FAMILY: 宋体; mso-hansi-font-family: 'Times New Roman'; mso-ascii-font-family: 'Times New Roman'">后的内容，这就是以后面的语句结果为他们顺序执行后的最终结果的原因，我们可以使用</SPAN><SPAN
lang=EN-US>Print[]</SPAN><SPAN
style="FONT-FAMILY: 宋体; mso-hansi-font-family: 'Times New Roman'; mso-ascii-font-family: 'Times New Roman'">语句输出想要的结果。例如在下面的语句中就是使用了</SPAN><SPAN
lang=EN-US>Print[]</SPAN><SPAN
style="FONT-FAMILY: 宋体; mso-hansi-font-family: 'Times New Roman'; mso-ascii-font-family: 'Times New Roman'">语句输出</SPAN><SPAN
lang=EN-US>f(1.2)</SPAN><SPAN
style="FONT-FAMILY: 宋体; mso-hansi-font-family: 'Times New Roman'; mso-ascii-font-family: 'Times New Roman'">值的顺序结构：</SPAN></b></font></P>
<P class=MsoNormal style="text-indent: 17.95pt; mso-list: skip; line-height: 200%"><SPAN
lang=EN-US><font size="4"><b>In[2]:=f[x_] = x^3 + 4x^2 + 6; Print[f[1.2]];</b></font></SPAN></P>
<P class=MsoNormal style="text-indent: 17.95pt; mso-list: skip; line-height: 200%"><SPAN
lang=EN-US><font size="4"><b>13.488</b></font></SPAN></P>
<P class=MsoNormal style="text-indent: 17.95pt; mso-list: skip; 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">此时程序直接输出结果。但由于绘图语句执行后，其图形在</font></b></SPAN><b><font size="4"><SPAN
lang=EN-US>Out</SPAN><SPAN
style="FONT-FAMILY: 宋体; mso-hansi-font-family: 'Times New Roman'; mso-ascii-font-family: 'Times New Roman'">语句出现之前画除，因而绘图命令后加“；”号时，图形仍会画出。此时并不输出</SPAN><SPAN
lang=EN-US>Out</SPAN><SPAN
style="FONT-FAMILY: 宋体; mso-hansi-font-family: 'Times New Roman'; mso-ascii-font-family: 'Times New Roman'">语句后的内容。</SPAN></font></b></P>
<P class=MsoNormal style="text-indent: 17.95pt; mso-list: skip; line-height: 200%"> </P>
<P class=MsoNormal style="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 color="#FF0000" size="5">三、<a name="循环结构">循环结构</a></font></b></SPAN></P>
<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'">在许多计算问题中，往往出现规律性的重复计算。例如计算：</SPAN><SPAN
lang=EN-US><SPAN style="mso-text-raise: -3.0pt"><!--[if gte vml 1]><V:SHAPETYPE
id=_x0000_t75 stroked="f" filled="f" path="m@4@5l@4@11@9@11@9@5xe"
o:preferrelative="t" o:spt="75" coordsize="21600,21600"> <V:STROKE
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