ch17_02.htm

unix基础教程

<table border="1" cellpadding="3"><tr><th><em class="emphasis">Character</em></tt></th><th><em class="emphasis">Translation</em></tt></th></tr>

<tr><td><tt class="literal">x dot</tt></td><td><img src="figs/xdot.gif" alt="Figure " /></td></tr>
<tr><td><tt class="literal">x dotdot</tt></td><td><img src="figs/xDot.gif" alt="Figure " /></td></tr>
<tr><td><tt class="literal">x hat</tt></td><td><img src="figs/xhat.gif" alt="Figure " /></td></tr>
<tr><td><tt class="literal">x tilde</tt></td><td><img src="figs/xtilde.gif" alt="Figure " /></td></tr>
<tr><td><tt class="literal">x vec</tt></td><td><img src="figs/xrarr.gif" alt="Figure " /></td></tr>
<tr><td><tt class="literal">x dyad</tt></td><td><img src="figs/xlrarr.gif" alt="Figure " /></td></tr>
<tr><td><tt class="literal">x bar</tt></td><td><img src="figs/xbar.gif" alt="Figure " /></td></tr>
<tr><td><tt class="literal">x under</tt></td><td><img src="figs/xubar.gif" alt="Figure " /></td></tr>
</table><p>
</div>

<a name="unut-ch-17-sect-2.7" /><div class="sect2"><h3 class="sect2">17.2.7. Keywords Recognized by eqn</h3><p>In addition to character names and diacritical marks,
<tt class="literal">eqn</tt> recognizes the following keywords.</p>

<table border="1" cellpadding="3">

<tr><td><tt class="literal">above</tt></td><td><p>Separate the pieces of a pile or matrix column.</p>
</td></tr>
<tr><td><tt class="literal">back</tt> <tt><em class="replaceable"><tt>n</em></tt></td><td><p>Move backwards horizontally <em class="emphasis">n</tt></em></tt> 1/100s of an em.</p>
</td></tr>
<tr><td><tt class="literal">bold</tt></td><td><p>Change to bold font.</p>
</td></tr>
<tr><td><tt class="literal">ccol</tt></td><td><p>Center-align a column of a matrix.</p>
</td></tr>
<tr><td><tt class="literal">cpile</tt></td><td><p>Make a centered pile (same as <tt class="literal">pile</tt>).</p>
</td></tr>
<tr><td><tt class="literal">define</tt></td><td><p>Create a name for a frequently used string.</p>
</td></tr>
<tr><td><tt class="literal">delim</tt> <tt><em class="replaceable"><tt>xy</tt></em></tt></td><td><p>Define two characters to mark the left and right ends of an <tt class="literal">eqn</tt>
equation to be printed inline.  Use <tt class="literal">delim off</tt> to turn off
delimiters.</p>
</td></tr>
<tr><td><tt class="literal">down</tt> <tt><em class="replaceable"><tt>n</em></tt></td><td><p>Move down <em class="emphasis">n</tt></em></tt> 1/100s of an em.</p>
</td></tr>
<tr><td><tt class="literal">fat</tt></td><td><p>Widen the current font by overstriking it.</p>
</td></tr>
<tr><td><tt class="literal">font</tt> <tt><em class="replaceable"><tt>x</tt></em></tt></td><td><p>

Change to font <em class="emphasis">x</em></tt>,
where <em class="emphasis">x</em></tt> is the name or 
number of a font.</p>
</td></tr>
<tr><td><tt class="literal">from</tt></td><td><p>Used in summations, integrals, and similar constructions to signify the
lower limit.</p>
</td></tr>
<tr><td><tt class="literal">fwd</tt> <tt><em class="replaceable"><tt>n</em></tt></td><td><p>Move forward horizontally <em class="emphasis">n</tt></em></tt> 1/100s of an em.</p>
</td></tr>
<tr><td><tt class="literal">gfont</tt> <tt><em class="replaceable"><tt>x</em></tt></td><td><p>Set a global font <em class="emphasis">x</tt></em></tt> for all equations.</p>
</td></tr>
<tr><td><tt class="literal">gsize</tt> <tt><em class="replaceable"><tt>n</tt></em></tt></td><td><p>Set a global size for all equations.</p>
</td></tr>
<tr><td><tt class="literal">italic</tt></td><td><p>Change to italic font.</p>
</td></tr>
<tr><td><tt class="literal">lcol</tt></td><td><p>Left-justify a column of a matrix.</p>
</td></tr>
<tr><td><tt class="literal">left</tt></td><td><p>Create big brackets, big braces, big bars, etc.</p>
</td></tr>
<tr><td><tt class="literal">lineup</tt></td><td><p>Line up marks in equations on different lines.</p>
</td></tr>
<tr><td><tt class="literal">lpile</tt></td><td><p>Left-justify the elements of a pile.</p>
</td></tr>
<tr><td><tt class="literal">mark</tt></td><td><p>Remember the horizontal position in an equation.  Used with <tt class="literal">lineup</tt>.</p>
</td></tr>
<tr><td><tt class="literal">matrix</tt></td><td><p>Create a matrix.</p>
</td></tr>
<tr><td><tt class="literal">ndefine</tt></td><td><p>Create a definition that takes effect only when <tt class="literal">neqn</tt> is running.</p>
</td></tr>
<tr><td><tt class="literal">over</tt></td><td><p>Make a fraction.</p>
</td></tr>
<tr><td><tt class="literal">pile</tt></td><td><p>Make a vertical pile with elements centered above each other.</p>
</td></tr>
<tr><td><tt class="literal">rcol</tt></td><td><p>Right-adjust a column of a matrix.</p>
</td></tr>
<tr><td><tt class="literal">right</tt></td><td><p>Create big brackets, big braces, big bars, etc.
Must have a matching <tt class="literal">left</tt>.</p>
</td></tr>
<tr><td><tt class="literal">roman</tt></td><td><p>Set following constant in roman.</p>
</td></tr>
<tr><td><tt class="literal">rpile</tt></td><td><p>Right-justify the elements of a pile.</p>
</td></tr>
<tr><td><tt class="literal">size</tt> <tt><em class="replaceable"><tt>n</em></tt></td><td><p>Change the size of the font to <em class="emphasis">n</tt></em></tt>.</p>
</td></tr>
<tr><td><tt class="literal">sqrt</tt></td><td><p>Take the square root of the following equation element.</p>
</td></tr>
<tr><td><tt class="literal">sub</tt></td><td><p>Start a subscript.</p>
</td></tr>
<tr><td><tt class="literal">sup</tt></td><td><p>Start a superscript.</p>
</td></tr>
<tr><td><tt class="literal">tdefine</tt></td><td><p>Make a definition that applies only to <tt class="literal">eqn</tt>.</p>
</td></tr>
<tr><td><tt class="literal">to</tt></td><td><p>Used in summations, integrals, and similar constructions to signify the
upper limit.</p>
</td></tr>
<tr><td><tt class="literal">up</tt> <tt><em class="replaceable"><tt>n</em></tt></td><td><p>Move up <em class="emphasis">n</tt></em></tt> 1/100s of an em.</p>
</td></tr>
<tr><td><tt class="literal">~</tt></td><td><p>Force extra space into the output.</p>
</td></tr>
<tr><td><tt class="literal">^</tt></td><td><p>Force a space one-half the size of the space forced by <tt class="literal">~</tt>.</p>
</td></tr>
<tr><td><tt class="literal">{ }</tt></td><td><p>Force <tt class="literal">eqn</tt> to treat an element as a unit.</p>
</td></tr>
<tr><td><tt class="literal">"..."</tt></td><td><p>A string within quotes is not subject to alterations by <tt class="literal">eqn</tt>.</p>
</td></tr>
</table><p>
</div>

<a name="unut-ch-17-sect-2.8" /><div class="sect2"><h3 class="sect2">17.2.8. Precedence</h3><p>If you don't use braces, <tt class="literal">eqn</tt> performs operations in the order shown in this list, reading from left to right.</p>

<table border="1" cellpadding="3"><tr><td><tt class="literal">dyad</tt></td><td><tt class="literal">vec</tt></td><td><tt class="literal">under</tt></td><td><tt class="literal">bar</tt></td></tr>
<tr><td><tt class="literal">tilde</tt></td><td><tt class="literal">hat</tt></td><td><tt class="literal">dot</tt></td><td><tt class="literal">dotdot</tt></td></tr>
<tr><td><tt class="literal">fwd</tt></td><td><tt class="literal">back</tt></td><td><tt class="literal">down</tt></td><td><tt class="literal">up</tt></td></tr>
<tr><td><tt class="literal">fat</tt></td><td><tt class="literal">roman</tt></td><td><tt class="literal">italic</tt></td><td><tt class="literal">bold</tt></td></tr>
<tr><td><tt class="literal">size</tt></td><td><tt class="literal">sub</tt></td><td><tt class="literal">sup</tt></td><td><tt class="literal">sqrt</tt></td></tr>
<tr><td><tt class="literal">over</tt></td><td><tt class="literal">from</tt></td><td><tt class="literal">to</tt></td><td>&nbsp;</td></tr>
</table><p>
<p>These operations group to the left:</p>

<table border="1" cellpadding="3"><tr><td><tt class="literal">over</tt></td><td><tt class="literal">sqrt</tt></td><td><tt class="literal">left</tt></td><td><tt class="literal">right</tt></td></tr>
</table><p>
<p>All others group to the right.</p>
<p><tt class="literal">eqn</tt> defines a language for writing mathematics.
Thus, there is a grammar with rules about how to group
and order items within the equation.
See the Bell Labs memorandum for the full story.</p>
</div>

<a name="unut-ch-17-sect-2.9" /><div class="sect2"><h3 class="sect2">17.2.9. eqn Examples</h3><p>Input:</p>
<blockquote><pre class="code">.EQ
delim %%
.EN
%sum from i=0 to inf c sup i~=~lim from {m -&gt; inf}
sum from i=0 to m c sup i%
.EQ
delim off
.EN</pre></blockquote>
<p>Result:</p>
<img src="figs/eq1.gif" alt="Figure 17.2.9" /><p>Input:</p>
<blockquote><pre class="code">.EQ
x ~=~ left [ { -b ~+-~ sqrt {b sup 2 - ~4ac} } 
over 2a right ]
.EN</pre></blockquote>
<p>Result:
<a name="IXT-17-123456" />
<a name="IXT-17-123457" />
<a name="IXT-17-123458" /></p>
<img src="figs/eq2.gif" alt="Figure 17.2.9" />
<a name="IXT-17-123459" />
<a name="IXT-17-123460" />
<a name="IXT-17-123461" /></div>


<hr width="684" align="left" />
<div class="navbar"><table width="684" border="0"><tr><td align="left" valign="top" width="228"><a href="ch17_01.htm"><img src="../gifs/txtpreva.gif" alt="Previous" border="0" /></a></td><td align="center" valign="top" width="228"><a href="index.htm"><img src="../gifs/txthome.gif" alt="Home" border="0" /></a></td><td align="right" valign="top" width="228"><a href="ch17_03.htm"><img src="../gifs/txtnexta.gif" alt="Next" border="0" /></a></td></tr><tr><td align="left" valign="top" width="228">17. troff Preprocessors</td><td align="center" valign="top" width="228"><a href="index/index.htm"><img src="../gifs/index.gif" alt="Book Index" border="0" /></a></td><td align="right" valign="top" width="228">17.3. pic</td></tr></table></div>
<hr width="684" align="left" />

<img src="../gifs/navbar.gif" usemap="#library-map" border="0" alt="Library Navigation Links" />
<p><p><font size="-1"><a href="copyrght.htm">Copyright &copy; 2003</a> O'Reilly &amp; Associates. All rights reserved.</font></p>

<map name="library-map">
<area shape="rect" coords="1,0,88,96" href="../index.htm"><area shape="rect" coords="90,0,165,96" href="../upt/index.htm"><area shape="rect" coords="168,1,253,107" href="../mac/index.htm"><area shape="rect" coords="255,0,335,97" href="../korn/index.htm"><area shape="rect" coords="337,0,415,109" href="../unixnut/index.htm"><area shape="rect" coords="417,0,512,122" href="../sedawk/index.htm"><area shape="rect" coords="514,0,605,105" href="../lunix/index.htm"><area shape="rect" coords="611,2,694,121" href="../vi/index.htm">
</map>

</body></html>