term% cat index.txt EQN(1) General Commands Manual EQN(1)
delim $$
NAME
eqn, neqn, checkeq - typeset mathematics
SYNOPSIS
eqn [ -dxy ] [ -pn ] [ -sn ] [ -fn ] [ -Tdest ] [ file ] ...
neqn [ option ] ... [ file ] ...
checkeq [ file ] ...
DESCRIPTION
Eqn is a troff(1) preprocessor for typesetting mathematics on a photo‐
typesetter, neqn on terminals. Usage is almost always
eqn file ... | troff
neqn file ... | nroff
If no files are specified, these programs read from the standard input.
Eqn prepares output for the typesetter named in the -T option (Mergen‐
thaler Linotron 202 default, see troff(1)).
A line beginning with `.EQ' marks the start of an equation; the end of
an equation is marked by a line beginning with `.EN'. Neither of these
lines is altered, so they may be defined in macro packages to get cen‐
tering, numbering, etc. It is also possible to set two characters as
`delimiters'; subsequent text between delimiters is also treated as eqn
input. Delimiters may be set to characters x and y with the command-
line argument -dxy or (more commonly) with `delim xy' between .EQ and
.EN. The left and right delimiters may be identical. Delimiters are
turned off by `delim off'. All text that is neither between delimiters
nor between .EQ and .EN is passed through untouched.
Checkeq reports missing or unbalanced delimiters and .EQ/.EN pairs.
Tokens within eqn are separated by spaces, tabs, newlines, braces, dou‐
ble quotes, tildes or circumflexes. Braces {} are used for grouping;
generally speaking, anywhere a single character like x could appear, a
complicated construction enclosed in braces may be used instead. Tilde
~ represents a full space in the output, circumflex ^ half as much, and
tab represents an ordinary troff tab character.
Subscripts and superscripts are produced with the keywords sub and sup.
Thus x sub i makes $x sub i$, a sub i sup 2 produces $a sub i sup 2$,
and e sup {x sup 2 + y sup 2} gives $e sup {x sup 2 + y sup 2}$.
Fractions are made with over: a over b yields $a over b$.
sqrt makes square roots: 1 over sqrt {ax sup 2 +bx+c} results in $1
over sqrt {ax sup 2 +bx+c}$ .
The keywords from and to introduce lower and upper limits on arbitrary
things: $lim from {n-> inf} sum from 0 to n x sub i$ is made with lim
from {n-> inf } sum from 0 to n x sub i.
Left and right brackets, braces, etc., of the right height are made
with left and right: left [ x sup 2 + y sup 2 over alpha right ] ~=~1
produces $left [ x sup 2 + y sup 2 over alpha right ] ~=~1$. The right
clause is optional. Legal characters after left and right are braces,
brackets, bars, c and f for ceiling and floor, and "" for nothing at
all (useful for a right-side-only bracket).
Vertical piles of things are made with pile, lpile, cpile, and rpile:
pile {a above b above c} produces $pile {a above b above c}$. There
can be an arbitrary number of elements in a pile. lpile left-justi‐
fies, pile and cpile center, with different vertical spacing, and rpile
right justifies.
Matrices are made with matrix: matrix { lcol { x sub i above y sub 2 }
ccol { 1 above 2 } } produces $matrix { lcol { x sub i above y sub 2 }
ccol { 1 above 2 } }$. In addition, there is rcol for a right-justi‐
fied column.
Diacritical marks are made with prime, dot, dotdot, hat, tilde, bar,
under, vec, dyad, and under: x sub 0 sup prime = f(t) bar + g(t) under
is $x sub 0 sup prime = f(t) bar + g(t) under$, and x vec= y dyad is $x
vec = y dyad$.
Sizes and font can be changed with size n or size ±n, roman, italic,
bold, and font n. Size and fonts can be changed globally in a document
by gsize n and gfont n, or by the command-line arguments -sn and -fn.
Normally subscripts and superscripts are reduced by 3 point sizes from
the previous size; this may be changed by the command-line argument
-pn.
Successive display arguments can be lined up. Place mark before the
desired lineup point in the first equation; place lineup at the place
that is to line up vertically in subsequent equations.
Shorthands may be defined or existing keywords redefined with define:
define thing % replacement % defines a new token called thing which
will be replaced by replacement whenever it appears thereafter. The %
may be any character that does not occur in replacement.
Keywords like sum ( sum ) int ( int ) inf ( inf ) and shorthands like
>= (>=) -> (->), and != ( != ) are recognized. Greek letters are
spelled out in the desired case, as in alpha or GAMMA. Mathematical
words like sin, cos, log are made Roman automatically. Troff(1) four-
character escapes like \(lh (☜) can be used anywhere. Strings enclosed
in double quotes "..." are passed through untouched; this permits key‐
words to be entered as text, and can be used to communicate with troff
when all else fails.
SEE ALSO
troff(1), tbl(1), ms(7), eqnchar(7), doctype(1)
B. W. Kernighan and L. L. Cherry, Typesetting Mathematics—User's Guide
J. F. Ossanna, NROFF/TROFF User's Manual
BUGS
To embolden digits, parens, etc., it is necessary to quote them, as in
`bold "12.3"'.
EQN(1)