ch19.htm

linux-unix130.linux.and.unix.ebooks130 linux and unix ebookslinuxLearning Linux - Collection of 12 E

care about a \char 43 sign.

</FONT></PRE>

<P>is processed by <TT>TeX</TT> as follows:</P>

<PRE><FONT COLOR="#0066FF">TeX would interpret % as a comment symbol but it would not

care about a + sign.

</FONT></PRE>

<H4 ALIGN="CENTER"><A NAME="Heading8<FONT COLOR="#000077">Controlling Spacing</FONT></H4>

<P>You've seen how you can insert individual extra spaces in <TT>TeX</TT> files.

Now, let's examine how you can have more control over the spacing of larger portions

of text. <TT>TeX</TT> has a series of commands that recognize the following units

of measurement:</P>

<CENTER>

<P><BR>



<TABLE BORDER="0" WIDTH="298">

	<TR ALIGN="LEFT" rowspan="1">

		<TD WIDTH="79" ALIGN="LEFT" VALIGN="TOP"><I>Unit</I></TD>

		<TD ALIGN="LEFT" VALIGN="TOP"><I>Meaning</I></TD>

	</TR>

	<TR ALIGN="LEFT" rowspan="1">

		<TD WIDTH="79" ALIGN="LEFT" VALIGN="TOP">em</TD>

		<TD ALIGN="LEFT" VALIGN="TOP">Approximately the width of the character M, depending on the font in use</TD>

	</TR>

	<TR ALIGN="LEFT" rowspan="1">

		<TD WIDTH="79" ALIGN="LEFT" VALIGN="TOP">in</TD>

		<TD ALIGN="LEFT" VALIGN="TOP">Inches</TD>

	</TR>

	<TR ALIGN="LEFT" rowspan="1">

		<TD WIDTH="79" ALIGN="LEFT" VALIGN="TOP">pt</TD>

		<TD ALIGN="LEFT" VALIGN="TOP">Points (1 inch equals 72.27 points)</TD>

	</TR>

	<TR ALIGN="LEFT" rowspan="1">

		<TD WIDTH="79" ALIGN="LEFT" VALIGN="TOP">mm</TD>

		<TD ALIGN="LEFT" VALIGN="TOP">Millimeters (1 inch equals 25.4 millimeters)</TD>

	</TR>

</TABLE>

</P>

</CENTER>

<P>These units are used with decimal numbers to specify the amount of spacing that

you need. The <TT>\hskip</TT> command can insert a horizontal space on a line, like

this:</P>

<PRE><FONT COLOR="#0066FF">\tt From here \hskip 0.5in to there

</FONT></PRE>

<P>This produces the following output:</P>

<PRE><FONT COLOR="#0066FF">From here      to there

</FONT></PRE>

<P>You can also supply a negative number, which moves the text following the <TT>\hskip</TT>

command to the left (the negative direction). The<TT> \hfil</TT> command distributes

horizontal space in a paragraph when space is available. The interesting thing about

the <TT>\hfil</TT> command is the fact that <TT>TeX</TT> inserts one implicitly for

each paragraph. Bearing this detail in mind, you can use this command to flush text

left or right, or center it on a line, like this:</P>

<PRE><FONT COLOR="#0066FF">

\noindent \hfil Some centered text. \par

</FONT></PRE>

<P>This is output as follows:</P>

<CENTER>

<PRE><FONT COLOR="#0066FF">Some centered text.



</FONT></PRE>

</CENTER>

<P>The <TT>\vskip</TT> command can insert a vertical space between paragraphs using

a given unit of measurement (much like <TT>\hskip</TT>). The command</P>

<PRE><FONT COLOR="#0066FF">\vskip 40mm

</FONT></PRE>

<P>places a vertical space of 40 millimeters between its preceding and succeeding

paragraphs. <TT>TeX</TT> also provides vertical skipping commands in convenient units:

<TT>\smallskip</TT>, <TT>\medskip</TT>, and <TT>\bigskip</TT>.</P>

<P>The vertical equivalent of <TT>\hfil</TT> is the <TT>\vfill</TT> command, which

can distribute vertical spaces between paragraphs when extra space (nontext) is available.

<TT>TeX</TT> assumes an implicit <TT>\vfill</TT> command at the end of a document.</P>

<P>You can also explicitly add line breaks and page breaks to your document with

the <TT>\break</TT> command. If this command appears within a paragraph, <TT>TeX</TT>

inserts a line break. If it appears between paragraphs, a page break is inserted.

Conversely, you can specify points in your document where you want the text to be

kept together and not broken across lines or pages. This is done by using the <TT>\nobreak</TT>

command.

<CENTER>

<H4><A NAME="Heading9<FONT COLOR="#000077">Page Layout</FONT></H4>

</CENTER>

<P>A page is composed of a header, footer, and body. The header and footer contain

information such as chapter title, section heading, and page number. The body is

where the main information in your document appears. By changing how this information

is ordered in your <TT>TeX</TT> document, you are actually designing the look of

the finished product.</P>

<P>The <TT>\headline</TT> and <TT>\footline</TT> commands both take arguments that

specify their content. The format of these commands is as follows:</P>

<PRE><FONT COLOR="#0066FF">\headline={parameters}

</FONT></PRE>

<P>The parameters could be a list of things such as a page number command and an

<TT>\hfil</TT> command:</P>

<PRE><FONT COLOR="#0066FF">\headline={\hfil \the\pageno}



\footline={\hfil}

</FONT></PRE>

<P>This pair of commands creates a right-justified page number and a blank footer

on each page.</P>

<P>You can change the size of the text box that <TT>TeX</TT> uses for paragraphs

by using the <TT>\hsize</TT> command. For instance, the text</P>

<PRE><FONT COLOR="#0066FF">\hsize=2in



This text is 2 inches wide but we could choose to make it wider or thinner.

</FONT></PRE>

<P>produces the following:</P>

<PRE><FONT COLOR="#0066FF">This text is 2 inches wide but we could choose to make it wider or thinner.

</FONT></PRE>

<P>Margins can be adjusted inward or outward using the <TT>\leftskip</TT> and <TT>\rightskip</TT>

commands, respectively. By providing positive values to these commands, they move

the margin inward, depending on which side you specify (left or right). As you may

expect, negative values have the opposite effect: They move the margins outward.

Indentation is controlled similarly using the <TT>\parindent</TT> command.</P>

<P>The<TT> \baselineskip</TT> and <TT>\parskip</TT> commands control the regular

vertical spacing between lines and paragraphs, as in the following:</P>

<PRE><FONT COLOR="#0066FF">\baselineskip=0.15in



\parskip=0.3in

</FONT></PRE>

<P>Baseline refers to the distance between the bottoms of characters (such as an

i) on consecutive lines.

<CENTER>

<H4><A NAME="Heading10<FONT COLOR="#000077">Using Groups</FONT></H4>

</CENTER>

<P>Normally, <TT>TeX</TT> continues using such things as fonts and text styles until

you explicitly change the format. The grouping features of <TT>TeX</TT> enable you

to define changes that are local to particular sections of text. The formatting originally

specified is then restored after the group has been processed.</P>

<P>There are two ways to specify how text is grouped. One is to use the <TT>\begingroup</TT>

and <TT>\endgroup</TT> command pair. The other is to use the braces <TT>{</TT> and

<TT>}</TT>. Although both of these perform grouping roles, braces are also used to

specify parameters to commands and, as such, must be used with care.</P>

<P>As an illustration of the use of groups in <TT>TeX</TT>, the text</P>

<PRE><FONT COLOR="#0066FF">Let's see \begingroup \it how {\bf this grouping stuff} really



works \endgroup, shall we?

</FONT></PRE>

<P>produces the following:</P>

<PRE><FONT COLOR="#0066FF">Let's see how this grouping stuff really

</FONT></PRE>

<PRE><FONT COLOR="#0066FF">works, shall we?

</FONT></PRE>

<P>You may have noted from the example that, in fact, groups can contain other groups.

<CENTER>

<H4><A NAME="Heading11<FONT COLOR="#000077">Mathematical Symbols</FONT></H4>

</CENTER>

<P>One of the most powerful features of <TT>TeX</TT> is its capability to generate

correct mathematical notation for formulas with convenient commands. This is one

of the key reasons behind <TT>TeX</TT>'s popularity among engineers and scientists.</P>

<P><TT>TeX</TT> distinguishes between formulas that must appear within regular text

(inline formulas) and those that must appear on their own line (displayed formulas).

You must use the <TT>$</TT> symbol to denote inline formulas, as in</P>

<PRE><FONT COLOR="#0066FF">The equation $2+3=x$ must evaluate to $x=5$.

</FONT></PRE>

<P>which is generated as the following:</P>

<PRE><FONT COLOR="#0066FF">The equation 2+3=x must evaluate to x=5.

</FONT></PRE>

<P>However, displayed formulas are denoted using two consecutive <TT>$</TT> symbols,

as in</P>

<PRE><FONT COLOR="#0066FF">The equation $$2+3=x$$ must evaluate to $$x=5$$.

</FONT></PRE>

<P>which produces the following:</P>

<PRE><FONT COLOR="#0066FF">        The equation



          2+3=x



must evaluate to



          x=5.

</FONT></PRE>

<P>Table 19.1 shows some of the math symbols that <TT>TeX</TT> can generate, their

associated commands, and their meaning.</P>

<CENTER>

<P><FONT SIZE="4"><B>Table 19.1. Some of the math symbols that TeX can generate.

</B></FONT>

<TABLE BORDER="0">

	<TR ALIGN="LEFT" rowspan="1">

		<TD ALIGN="LEFT"><I>Symbol</I></TD>

		<TD ALIGN="LEFT"><I><TT>TeX</TT> Command</I></TD>

		<TD ALIGN="LEFT"><I>Meaning</I></TD>

	</TR>

	<TR ALIGN="LEFT" rowspan="1">

		<TD ALIGN="LEFT">[Pi]</TD>

		<TD ALIGN="LEFT"><TT>\pi</TT></TD>

		<TD ALIGN="LEFT">Pi</TD>

	</TR>

	<TR ALIGN="LEFT" rowspan="1">

		<TD ALIGN="LEFT">[Sigma]</TD>

		<TD ALIGN="LEFT"><TT>\sum</TT></TD>

		<TD ALIGN="LEFT">Sum</TD>

	</TR>

	<TR ALIGN="LEFT" rowspan="1">

		<TD ALIGN="LEFT">{</TD>

		<TD ALIGN="LEFT"><TT>\{</TT></TD>

		<TD ALIGN="LEFT">Open bracket</TD>

	</TR>

	<TR ALIGN="LEFT" rowspan="1">

		<TD ALIGN="LEFT">}</TD>

		<TD ALIGN="LEFT"><TT>\}</TT></TD>

		<TD ALIGN="LEFT">Close bracket</TD>

	</TR>

	<TR ALIGN="LEFT" rowspan="1">

		<TD ALIGN="LEFT">[florin]</TD>

		<TD ALIGN="LEFT"><TT>\int</TT></TD>

		<TD ALIGN="LEFT">Integral</TD>

	</TR>

	<TR ALIGN="LEFT" rowspan="1">

		<TD ALIGN="LEFT">&lt;=</TD>

		<TD ALIGN="LEFT"><TT>\leq</TT></TD>

		<TD ALIGN="LEFT">Less than or equal to</TD>

	</TR>

	<TR ALIGN="LEFT" rowspan="1">

		<TD ALIGN="LEFT">&gt;=</TD>

		<TD ALIGN="LEFT"><TT>\geq</TT></TD>

		<TD ALIGN="LEFT">Greater than or equal to</TD>

	</TR>

	<TR ALIGN="LEFT" rowspan="1">

		<TD ALIGN="LEFT">!=</TD>

		<TD ALIGN="LEFT"><TT>\neq</TT></TD>

		<TD ALIGN="LEFT">Not equal to</TD>

	</TR>

	<TR ALIGN="LEFT" rowspan="1">

		<TD ALIGN="LEFT"><BR>

			*</TD>

		<TD ALIGN="LEFT"><TT>\bullet</TT></TD>

		<TD ALIGN="LEFT">Bullet</TD>

	</TR>

	<TR ALIGN="LEFT" rowspan="1">

		<TD ALIGN="LEFT">...</TD>

		<TD ALIGN="LEFT"><TT>\ldots</TT></TD>

		<TD ALIGN="LEFT">Horizontal ellipses</TD>

	</TR>

	<TR ALIGN="LEFT" rowspan="1">

		<TD ALIGN="LEFT">D</TD>

		<TD ALIGN="LEFT"><TT>\diamond</TT></TD>

		<TD ALIGN="LEFT">Diamond</TD>

	</TR>

	<TR ALIGN="LEFT" rowspan="1">

		<TD ALIGN="LEFT">[Delta]</TD>

		<TD ALIGN="LEFT"><TT>\Delta</TT></TD>