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<A NAME="PAGENUM-202"><P>Page 202</P></A>
<H3><A NAME="ch01_ 84">
geqn
</A></H3>
<P>geqn—Format equations for troff
</P>
<P><B>
SINOPSIS
</B>
</P>
<!-- CODE SNIP //-->
<PRE>
geqn [ _rvCNR ][_dcc ][_Tname ][_Mdir ][_fF ][_sn ][_pn ][_mn ][files ... ]
</PRE>
<!-- END CODE SNIP //-->
<P><B>
DESCRIPTION
</B>
</P>
<P>This manual page describes the GNU version of
eqn, which is part of the groff document formatting system.
eqn compiles descriptions of equations embedded within
troff input files into commands that are understood by
troff. Normally, it should be invoked using the _e option of
groff. The syntax is quite compatible with UNIX
eqn. The output of GNU eqn cannot be processed with UNIX
troff; it must be processed with GNU troff. If no files are given on the command line,
the standard input will be read. A filename of _ will cause the standard input to be read.
</P>
<P>eqn searches for the file eqnrc using the path
.:/usr/lib/groff/tmac:/usr/lib/tmac. If it exists,
eqn will process it before the other input files. The
_R option prevents this.
</P>
<P>GNU eqn does not provide the functionality of
neqn: it does not support low-resolution, typewriter-like devices (although
it may work adequately for very simple input).
</P>
<P><B>
OPTIONS
</B>
</P>
<TABLE>
<TR><TD>
_C
</TD><TD>
Recognize .EQ and .EN even when followed by a character other than space or newline.
</TD></TR><TR><TD>
_N
</TD><TD>
Don't allow newlines within delimiters. This option allows
eqn to recover better from missing closing delimiters.
</TD></TR><TR><TD>
_v
</TD><TD>
Print the version number.
</TD></TR><TR><TD>
_r
</TD><TD>
Only one size reduction.
</TD></TR><TR><TD>
_mn
</TD><TD>
The minimum point-size is n. eqn will not reduce the size of subscripts or superscripts to a smaller size <BR>
than n.
</TD></TR><TR><TD>
_Tname
</TD><TD>
The output is for device name. The only effect of this is to define a macro
name with a value of 1. Typically, eqnrc will use this to provide definitions appropriate for the output device. The default output device is
ps.
</TD></TR><TR><TD>
_Mdir
</TD><TD>
Search dir for eqnrc before the default directories.
</TD></TR><TR><TD>
_R
</TD><TD>
Don't load eqnrc.
</TD></TR><TR><TD>
_fF
</TD><TD>
This is equivalent to a gfontF command.
</TD></TR><TR><TD>
_sn
</TD><TD>
This is equivalent to a gsizen command. This option is deprecated.
eqn will normally set equations at whatever the current
pointsize is when the equation is encountered.
</TD></TR><TR><TD>
_pn
</TD><TD>
This says that subscripts and superscripts should be
n points smaller than the surrounding text. This
option is deprecated. Normally, eqn makes sets subscripts and superscripts at 70 percent of the size of
the surrounding text.
</TD></TR></TABLE>
<P><B>
USAGE
</B>
</P>
<P>Only the differences between GNU eqn and UNIX
eqn are described here.
</P>
<P>Most of the new features of GNU eqn are based on TeX. There are some references to the differences between TeX
and GNU eqn as follows; these may safely be ignored if you do not know TeX.
</P>
<P><B>
AUTOMATIC SPACING
</B>
</P>
<P>eqn gives each component of an equation a type, and adjusts the spacing between components using that type. Possible
types are
</P>
<TABLE>
<TR><TD>
ordinary
</TD><TD>
An ordinary character such as 1 or
x
</TD></TR><TR><TD>
operator
</TD><TD>
A large operator such as ;
</TD></TR><TR><TD>
binary
</TD><TD>
A binary operator such as +
</TD></TR><TR><TD>
relation
</TD><TD>
A relation such as =
</TD></TR></TABLE>
<A NAME="PAGENUM-203"><P>Page 203</P></A>
<TABLE>
<TR><TD>
opening
</TD><TD>
An opening bracket such as (
</TD></TR><TR><TD>
closing
</TD><TD>
A closing bracket such as )
</TD></TR><TR><TD>
punctuation
</TD><TD>
A punctuation character such as
,
</TD></TR><TR><TD>
inner
</TD><TD>
A subformula contained within brackets
</TD></TR><TR><TD>
suppress
</TD><TD>
Spacing that suppresses automatic spacing adjustment
</TD></TR></TABLE>
<P>Components of an equation get a type in one of two ways:
</P>
<TABLE>
<TR><TD>
typete
</TD><TD>
This yields an equation component that contains
e but that has type t, where t is one of the types mentioned previously. For example, times is defined as
type "binary" \(mu
The name of the type doesn't have to be quoted, but quoting protects from macro expansion.
</TD></TR><TR><TD>
chartypettext
</TD><TD>
Unquoted groups of characters are split up into individual characters, and the type of each character
is looked up; this changes the type that is stored for each character; it says that the characters in
text from now on have type t. For example
chartype "punctuation" .,;:
would make the characters .,;: have type
punctuation whenever they subsequently appeared in
an equation. The type t can also be letter or digit; in these cases,
chartype changes the font type of the characters. See the "Fonts" section, later in this manual page.
</TD></TR></TABLE>
<P><B>
NEW PRIMITIVES
</B>
</P>
<TABLE>
<TR><TD>
e1smallovere2
</TD><TD>
This is similar to over;
smallover reduces the size of e1 and e2; it also puts less vertical space between
e1 or e2 and the fraction bar. The over primitive corresponds to the
\over primitive in display styles; smallover corresponds to
\over in nondisplay styles.
</TD></TR><TR><TD>
vcentere
</TD><TD>
This vertically centers e about the math axis. The math axis is the vertical position about which
characters such as + and - are centered; also it is the vertical position used for the bar of fractions. For example,
sum is defined as
{ type "operator" vcenter size +5 \(*S }
</TD></TR><TR><TD>
e1accente2
</TD><TD>
This sets e2 as an accent over
e1. e2 is assumed to be at the correct height for a lowercase letter;
e2 will be moved down according if e1 is taller or shorter than a lowercase letter. For example,
hat is defined as
accent { "^" }
dotdot, dot, tilde, vec, and dyad are also defined using the
accent primitive.
</TD></TR><TR><TD>
e1uaccente2
</TD><TD>
This sets e2 as an accent under
e1. e2 is assumed to be at the correct height for a character without
a descender; e2 will be moved down if e1 has a descender.
utilde is predefined using uaccent as a tilde
accent below the baseline.
</TD></TR><TR><TD>
splittext
</TD><TD>
This has the same effect as simply
text, but text is not subject to macro expansion because it is
quoted; text will be split up and the spacing between individual characters will be adjusted.
</TD></TR><TR><TD>
nosplittext
</TD><TD>
This has the same effect as
text, but because text is not quoted it will be subject to macro expansion;
text will not be split up and the spacing between individual characters will not be adjusted.
</TD></TR><TR><TD>
eopprime
</TD><TD>
This is a variant of prime that acts as an operator on
e.It produces a different result from prime in a
case such as Aopprimesub1: With opprime the 1 will be tucked under the prime as a subscript to the
A (as is conventional in mathematical typesetting), whereas with
prime the 1 will be a subscript to the prime character. The precedence of
opprime is the same as that of bar and under, which is higher than that
of everything except accent and uaccent. In unquoted text, a
` that is not the first character will be treated like
opprime.
</TD></TR><TR><TD>
specialtexte
</TD><TD>
This constructs a new object from
e using a gtroff(1) macro named text. When the macro is called,
the string 0s will contain the output for e, and the number registers
0w, 0h, 0d, 0skern and 0skew will contain the width, height, depth, subscript kern, and skew of
e. (The subscript kern of an object says how much
a subscript on that object should be tucked in; the
skew of an object says how far to the right of the center
of the object an accent over the object should be placed.) The macro must modify
0s so that it will output the desired result with its origin at the current point, and increase the current horizontal position by
the width of the object. The number registers must also be modified so that they correspond to the result.
</TD></TR></TABLE>
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