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style='font-size:12.0pt;font-family:宋体;color:#993366'>==<o:p></o:p></span></p>
<p class=MsoNormal align=left style='margin-left:10.9pt;text-align:left;
line-height:17.0pt;mso-line-height-rule:exactly'><span lang=EN-US
style='font-size:12.0pt;font-family:宋体;color:#993366'>/=</span><span
lang=EN-US style='font-size:12.0pt;font-family:宋体'><o:p></o:p></span></p>
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none;border-bottom:solid windowtext 1.0pt;border-right:solid windowtext 1.0pt;
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<p class=MsoNormal style='margin-left:17.05pt;line-height:17.0pt;mso-line-height-rule:
exactly'><span lang=EN-US style='font-size:12.0pt;font-family:宋体'>Greater
Than<o:p></o:p></span></p>
<p class=MsoNormal style='margin-left:17.05pt;line-height:17.0pt;mso-line-height-rule:
exactly'><span lang=EN-US style='font-size:12.0pt;font-family:宋体'>Greater
than or Equal to<o:p></o:p></span></p>
<p class=MsoNormal style='margin-left:17.05pt;line-height:17.0pt;mso-line-height-rule:
exactly'><span lang=EN-US style='font-size:12.0pt;font-family:宋体'>Less Than<o:p></o:p></span></p>
<p class=MsoNormal style='margin-left:17.05pt;line-height:17.0pt;mso-line-height-rule:
exactly'><span lang=EN-US style='font-size:12.0pt;font-family:宋体'>Less than
or Equal to<o:p></o:p></span></p>
<p class=MsoNormal style='margin-left:17.05pt;line-height:17.0pt;mso-line-height-rule:
exactly'><span lang=EN-US style='font-size:12.0pt;font-family:宋体'>EQual to<o:p></o:p></span></p>
<p class=MsoNormal style='margin-left:17.05pt;line-height:17.0pt;mso-line-height-rule:
exactly'><span lang=EN-US style='font-size:12.0pt;font-family:宋体'>Not Equal
to<o:p></o:p></span></p>
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none;border-bottom:solid windowtext 1.0pt;border-right:solid windowtext 1.0pt;
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<p class=MsoNormal style='margin-left:12.85pt;line-height:17.0pt;mso-line-height-rule:
exactly'><span lang=ZH-CN style='font-size:12.0pt;font-family:宋体'>＞</span><span
lang=EN-US style='font-size:12.0pt;font-family:宋体'> (</span><span lang=ZH-CN
style='font-size:12.0pt;font-family:宋体'>大于</span><span lang=EN-US
style='font-size:12.0pt;font-family:宋体'>)<o:p></o:p></span></p>
<p class=MsoNormal style='margin-left:12.85pt;line-height:17.0pt;mso-line-height-rule:
exactly'><span lang=ZH-CN style='font-size:12.0pt;font-family:宋体'>≥</span><span
lang=EN-US style='font-size:12.0pt;font-family:宋体'> (</span><span lang=ZH-CN
style='font-size:12.0pt;font-family:宋体'>大于或等于</span><span lang=EN-US
style='font-size:12.0pt;font-family:宋体'>)<o:p></o:p></span></p>
<p class=MsoNormal style='margin-left:12.85pt;line-height:17.0pt;mso-line-height-rule:
exactly'><span lang=ZH-CN style='font-size:12.0pt;font-family:宋体'>＜</span><span
lang=EN-US style='font-size:12.0pt;font-family:宋体'> (</span><span lang=ZH-CN
style='font-size:12.0pt;font-family:宋体'>小于</span><span lang=EN-US
style='font-size:12.0pt;font-family:宋体'>)<o:p></o:p></span></p>
<p class=MsoNormal style='margin-left:12.85pt;line-height:17.0pt;mso-line-height-rule:
exactly'><span lang=ZH-CN style='font-size:12.0pt;font-family:宋体'>≤</span><span
lang=EN-US style='font-size:12.0pt;font-family:宋体'> (</span><span lang=ZH-CN
style='font-size:12.0pt;font-family:宋体'>小于或等于</span><span lang=EN-US
style='font-size:12.0pt;font-family:宋体'>)<o:p></o:p></span></p>
<p class=MsoNormal style='margin-left:12.85pt;line-height:17.0pt;mso-line-height-rule:
exactly'><span lang=ZH-CN style='font-size:12.0pt;font-family:宋体'>＝</span><span
lang=EN-US style='font-size:12.0pt;font-family:宋体'> (</span><span lang=ZH-CN
style='font-size:12.0pt;font-family:宋体'>等于</span><span lang=EN-US
style='font-size:12.0pt;font-family:宋体'>)<o:p></o:p></span></p>
<p class=MsoNormal style='margin-left:12.85pt;line-height:17.0pt;mso-line-height-rule:
exactly'><span lang=ZH-CN style='font-size:12.0pt;font-family:宋体'>≠</span><span
lang=EN-US style='font-size:12.0pt;font-family:宋体'> (</span><span lang=ZH-CN
style='font-size:12.0pt;font-family:宋体'>不等于</span><span lang=EN-US
style='font-size:12.0pt;font-family:宋体'>)<o:p></o:p></span></p>
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<p class=MsoNormal style='margin-top:12.0pt'><span lang=ZH-CN style='font-size:
12.0pt;font-family:宋体'>注意：关系运算符的两个字母</span><span lang=EN-US style='font-size:
12.0pt;font-family:宋体'>(</span><span lang=ZH-CN style='font-size:12.0pt;
font-family:宋体'>如</span><span lang=EN-US style='font-size:12.0pt;font-family:
宋体'>GT</span><span lang=ZH-CN style='font-size:12.0pt;font-family:宋体'>，</span><span
lang=EN-US style='font-size:12.0pt;font-family:宋体'>LE</span><span lang=ZH-CN
style='font-size:12.0pt;font-family:宋体'>…</span><span lang=EN-US
style='font-size:12.0pt;font-family:宋体'>)</span><span lang=ZH-CN
style='font-size:12.0pt;font-family:宋体'>的二侧各有一个点，不要漏写。</span><span lang=EN-US
style='font-size:12.0pt;font-family:宋体'><o:p></o:p></span></p>
<p><a name="第2_2_1b"><span lang=EN-US style='font-family:宋体;color:red'>b)</span></a><span
lang=EN-US style='font-family:宋体;color:red'> </span><span lang=ZH-CN
style='font-family:宋体;color:red'>关系表达式</span><span lang=EN-US style='font-family:
宋体;color:red'><o:p></o:p></span></p>
<p class=MsoNormal style='text-indent:24.0pt;mso-char-indent-count:2.0;
line-height:17.0pt;mso-line-height-rule:exactly;mso-char-indent-size:12pt'><span
lang=ZH-CN style='font-size:12.0pt;font-family:宋体;color:fuchsia'>关系表达式</span><span
lang=ZH-CN style='font-size:12.0pt;font-family:宋体'>是最简单的一种<span
style='color:fuchsia'>逻辑表达式</span>。其一般形式为：</span><span lang=EN-US
style='font-size:12.0pt;font-family:宋体'><o:p></o:p></span></p>
<p class=MsoNormal style='margin-left:21.2pt;mso-para-margin-left:2.02gd;
text-indent:24.0pt;mso-char-indent-count:2.0;line-height:17.0pt;mso-line-height-rule:
exactly'><span lang=EN-US style='font-size:12.0pt;font-family:宋体;color:#FF9900'><</span><span
lang=ZH-CN style='font-size:12.0pt;font-family:宋体;color:#FF9900'>算术表达式</span><span
lang=EN-US style='font-size:12.0pt;font-family:宋体;color:#FF9900'>> <</span><span
lang=ZH-CN style='font-size:12.0pt;font-family:宋体;color:#FF9900'>关系运算符</span><span
lang=EN-US style='font-size:12.0pt;font-family:宋体;color:#FF9900'>> <</span><span
lang=ZH-CN style='font-size:12.0pt;font-family:宋体;color:#FF9900'>算术表达式</span><span
lang=EN-US style='font-size:12.0pt;font-family:宋体;color:#FF9900'>><o:p></o:p></span></p>
<p class=MsoNormal style='margin-left:21.2pt;mso-para-margin-left:2.02gd;
text-indent:24.0pt;mso-char-indent-count:2.0;line-height:17.0pt;mso-line-height-rule:
exactly'><span lang=EN-US style='font-size:12.0pt;font-family:宋体;color:#FF9900'><</span><span
lang=ZH-CN style='font-size:12.0pt;font-family:宋体;color:#FF9900'>字符表达式</span><span
lang=EN-US style='font-size:12.0pt;font-family:宋体;color:#FF9900'>> <</span><span
lang=ZH-CN style='font-size:12.0pt;font-family:宋体;color:#FF9900'>关系运算符</span><span
lang=EN-US style='font-size:12.0pt;font-family:宋体;color:#FF9900'>> <</span><span
lang=ZH-CN style='font-size:12.0pt;font-family:宋体;color:#FF9900'>字符表达式</span><span
lang=EN-US style='font-size:12.0pt;font-family:宋体;color:#FF9900'>><o:p></o:p></span></p>
<p class=MsoNormal style='text-indent:24.0pt;mso-char-indent-count:2.0;
line-height:17.0pt;mso-line-height-rule:exactly'><span lang=ZH-CN
style='font-size:12.0pt;font-family:宋体'>算术表达式也可以是一个算术量，即为一个数值常数、数值型变量、数值函数。</span><span
lang=EN-US style='font-size:12.0pt;font-family:宋体'><o:p></o:p></span></p>
<p class=MsoNormal style='line-height:17.0pt;mso-line-height-rule:exactly'><span
lang=ZH-CN style='font-size:12.0pt;font-family:宋体'>例：</span><span lang=EN-US
style='font-size:12.0pt;font-family:宋体'>A+B <= 0.<span
style='mso-spacerun:yes'> </span>A+B .LE. 0.<span
style='mso-spacerun:yes'> </span>A*B /= C/D<span
style='mso-spacerun:yes'> </span>A*B .NE. C/D<o:p></o:p></span></p>
<p class=MsoNormal style='text-indent:24.0pt;mso-char-indent-count:2.0;
line-height:17.0pt;mso-line-height-rule:exactly;mso-char-indent-size:12pt'><span
lang=ZH-CN style='font-size:12.0pt;font-family:宋体'>应当注意，关系表达式中关系操作符只准出现一次。数学中不等式写法与</span><span
lang=EN-US style='font-size:12.0pt;font-family:宋体'>FORTRAN</span><span
lang=ZH-CN style='font-size:12.0pt;font-family:宋体'>中关系表达式的写法有同有异，在编写关系表一定要严格服从它的一般形式。不可随意使用数学中的习惯用法，例如语句写法</span><span
lang=EN-US style='font-size:12.0pt;font-family:宋体'> 3</span><span lang=ZH-CN
style='font-size:12.0pt;font-family:宋体'>＜</span><span lang=EN-US
style='font-size:12.0pt;font-family:宋体'>X</span><span lang=ZH-CN
style='font-size:12.0pt;font-family:宋体'>＜</span><span lang=EN-US
style='font-size:12.0pt;font-family:宋体'>7 </span><span lang=ZH-CN
style='font-size:12.0pt;font-family:宋体'>就是不正确的关系表达式，因为它不符合关系表达式中只允许有一个关系操作符的规定。</span><span
lang=EN-US style='font-size:12.0pt;font-family:宋体'><o:p></o:p></span></p>
<p class=MsoNormal style='text-indent:24.0pt;mso-char-indent-count:2.0;
line-height:17.0pt;mso-line-height-rule:exactly;mso-char-indent-size:12pt'><span
lang=ZH-CN style='font-size:12.0pt;font-family:宋体'>关系运算的特点是：</span><span
lang=EN-US style='font-size:12.0pt;font-family:宋体'><o:p></o:p></span></p>
<p class=MsoNormal style='margin-left:49.65pt;text-indent:-24.0pt;line-height:
17.0pt;mso-line-height-rule:exactly;mso-list:l0 level2 lfo2;tab-stops:list 49.65pt 69.0pt'><![if !supportLists]><span
lang=EN-US style='font-size:12.0pt;font-family:Symbol;mso-fareast-font-family:
Symbol;mso-bidi-font-family:Symbol'><span style='mso-list:Ignore'><img
width=13 height=13 src="Sec2-2.files/image001.gif" alt="*"><span
style='font:7.0pt "Times New Roman"'>
</span></span></span><![endif]><span lang=ZH-CN style='font-size:12.0pt;
font-family:宋体'>关系表达式中包括算术运算符和关系运算符，其运算的次序是先进行算术运算，然后进行关系运算。</span><span
lang=EN-US style='font-size:12.0pt;font-family:宋体'><o:p></o:p></span></p>
<p class=MsoNormal style='margin-left:49.65pt;text-indent:-24.0pt;line-height:
17.0pt;mso-line-height-rule:exactly;mso-list:l0 level2 lfo2;tab-stops:list 49.65pt 69.0pt'><![if !supportLists]><span
lang=EN-US style='font-size:12.0pt;font-family:Symbol;mso-fareast-font-family:
Symbol;mso-bidi-font-family:Symbol'><span style='mso-list:Ignore'><img
width=13 height=13 src="Sec2-2.files/image001.gif" alt="*"><span
style='font:7.0pt "Times New Roman"'>
</span></span></span><![endif]><span lang=ZH-CN style='font-size:12.0pt;
font-family:宋体'>不同类型的数值量进行比较时，系统会先将这两个量转换成同一个类型，然后再比较。转换的规律是将低级类型向高级类型转换。因此，执行关系表达式的过程为：算出算术表达式的值；将两个算术表达式值转换成同一类型；将两个表达式的值进行比较。</span><span
lang=EN-US style='font-size:12.0pt;font-family:宋体'><o:p></o:p></span></p>
<p class=MsoNormal style='margin-left:49.65pt;text-indent:-24.0pt;line-height:
17.0pt;mso-line-height-rule:exactly;mso-list:l0 level2 lfo2;tab-stops:list 49.65pt 69.0pt'><![if !supportLists]><span
lang=EN-US style='font-size:12.0pt;font-family:Symbol;mso-fareast-font-family:
Symbol;mso-bidi-font-family:Symbol'><span style='mso-list:Ignore'><img
width=13 height=13 src="Sec2-2.files/image001.gif" alt="*"><span
style='font:7.0pt "Times New Roman"'>
</span></span></span><![endif]><span lang=ZH-CN style='font-size:12.0pt;
font-family:宋体'>关系表达式的值不是一个数值，而是一个逻辑量。它的值是“真”和“假”二者之一。</span><span lang=EN-US
style='font-size:12.0pt;font-family:宋体'><o:p></o:p></span></p>
<p class=MsoNormal style='margin-left:49.65pt;text-indent:-24.0pt;line-height:
17.0pt;mso-line-height-rule:exactly;mso-list:l0 level2 lfo2;tab-stops:list 49.65pt 69.0pt'><![if !supportLists]><span
lang=EN-US style='font-size:12.0pt;font-family:Symbol;mso-fareast-font-family:
Symbol;mso-bidi-font-family:Symbol'><span style='mso-list:Ignore'><img
width=13 height=13 src="Sec2-2.files/image001.gif" alt="*"><span
style='font:7.0pt "Times New Roman"'>
</span></span></span><![endif]><span lang=ZH-CN style='font-size:12.0pt;
font-family:宋体'>由于实数的精度限制，因此用</span><span lang=EN-US style='font-size:12.0pt;
font-family:宋体'>.EQ.(</span><span lang=ZH-CN style='font-size:12.0pt;
font-family:宋体'>等于</span><span lang=EN-US style='font-size:12.0pt;font-family:
宋体'>)</span><span lang=ZH-CN style='font-size:12.0pt;font-family:宋体'>和</span><span
lang=EN-US style='font-size:12.0pt;font-family:宋体'>.NE.(</span><span
lang=ZH-CN style='font-size:12.0pt;font-family:宋体'>不等于</span><span lang=EN-US
style='font-size:12.0pt;font-family:宋体'>)</span><span lang=ZH-CN
style='font-size:12.0pt;font-family:宋体'>运算符时要特别注意。要考虑到可能出现的误差，并设法弥补。如对数学式</span><span
lang=EN-US style='font-size:12.0pt;font-family:宋体'>A=B</span><span lang=ZH-CN
style='font-size:12.0pt;font-family:宋体'>的关系运算可用：</span><span lang=EN-US
style='font-size:12.0pt;font-family:宋体'>ABS(A-B).LT.1.E-30</span><span
lang=ZH-CN style='font-size:12.0pt;font-family:宋体'>；对</span><span lang=EN-US
style='font-size:12.0pt;font-family:宋体'>A</span><span lang=ZH-CN
style='font-size:12.0pt;font-family:宋体'>≠</span><span lang=EN-US
style='font-size:12.0pt;font-family:宋体'>B</span><span lang=ZH-CN
style='font-size:12.0pt;font-family:宋体'>可用：</span><span lang=EN-US
style='font-size:12.0pt;font-family:宋体'>ABS(A-B).GT.1.E-30</span><span
lang=ZH-CN style='font-size:12.0pt;font-family:宋体'>。</span><span lang=EN-US
style='font-size:12.0pt;font-family:宋体'><o:p></o:p></span></p>
<p class=MsoNormal style='margin-left:49.65pt;text-indent:-24.0pt;line-height:
17.0pt;mso-line-height-rule:exactly;mso-list:l0 level2 lfo2;tab-stops:list 49.65pt 69.0pt'><![if !supportLists]><span
lang=EN-US style='font-size:12.0pt;font-family:Symbol;mso-fareast-font-family:
Symbol;mso-bidi-font-family:Symbol'><span style='mso-list:Ignore'><img
width=13 height=13 src="Sec2-2.files/image001.gif" alt="*"><span
style='font:7.0pt "Times New Roman"'>
</span></span></span><![endif]><span lang=ZH-CN style='font-size:12.0pt;
font-family:宋体'>除了算术量可进行比较外，字符关系表达式可对两个字符量进行比较。</span><span lang=EN-US
style='font-size:12.0pt;font-family:宋体'><o:p></o:p></span></p>
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