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<p><strong><big><big><big><font COLOR="#0000FF">4.8.2 While 循环</font></big></big></big></strong></p>
<p><big><font COLOR="#0000FF">While
语句用于满足一定条件的循环，语法结构如下：</font></big></p>
<hr>
<p><font COLOR="#FF0000">while</font></p>
<p><font COLOR="#FF0000">while expression</font> <br>
<br>
<font COLOR="#FF0000">command group A</font> <br>
<br>
<font COLOR="#FF0000">end</font> <br>
<br>
<br>
<font COLOR="#FF0000">sum = 0;</font> <br>
<br>
<font COLOR="#FF0000">k = 1;</font> <br>
<br>
<font COLOR="#FF0000">while x(k) >= 0 & k <= length(k)</font> <br>
<br>
<font COLOR="#FF0000">sum = sum + x(k);</font> <br>
<br>
<font COLOR="#FF0000">k = k+1;</font> <br>
<br>
<font COLOR="#FF0000">end</font> </p>
<p>此外可以利用<font color="#FF0000">break</font>命令跳出<font color="#FF0000">for</font>,<font color="#FF0000">while</font>循环,如下例，计算MATLAB可以计算的最小正值：</p>
<p><font COLOR="#FF0000">>> num=0; EPS=1; <br>
<br>
>> for num=1:1000 <br>
<br>
EPS=EPS/2; <br>
<br>
if (1+EPS) <= 1 <br>
<br>
break <br>
<br>
end <br>
<br>
end <br>
<br>
>> EPS, num <br>
<br>
>> EPS = <br>
<br>
1.1102e-016 <br>
<br>
>> num = <br>
<br>
53 </font></p>
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