EQN(1) EQN(1)
delim $$
NAME
eqn - typeset mathematics
SYNOPSIS
eqn [ option ... ] [ file ... ]
DESCRIPTION
Eqn is a troff(1) preprocessor for typesetting mathematics
on a typesetter. Usage is almost always
eqn file ... | troff
If no files are specified, eqn reads from the standard
input. Eqn prepares output for the typesetter named in the
-Tdest option (default -Tutf; see troff(1)). When run with
other preprocessor filters, eqn usually comes last.
A line beginning with .EQ marks the start of an equation;
the end of an equation is marked by a line beginning with
.EN. Neither of these lines is altered, so they may be
defined in macro packages to get centering, numbering, etc.
It is also possible to set two characters as `delimiters';
text between delimiters is also eqn input. Delimiters may
be set to characters x and y with the option -dxy or (more
commonly) with delim xy between .EQ and .EN. Left and right
delimiters may be identical. (They are customarily taken to
be $font L "$$" )$. Delimiters are turned off by `delim
off'. All text that is neither between delimiters nor
between .EQ and .EN is passed through untouched.
Tokens within eqn are separated by spaces, tabs, newlines,
braces, double 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 `~' repre-
sents a full space in the output, circumflex `^' half as
much.
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 $e sup {x sup 2 + y sup 2}$.
Over makes fractions: `a over b' yields $a over b$.
Sqrt produces 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: $lim from {n -> inf} sum from 0 to n x sub
Page 1 Plan 9 (printed 12/21/24)
EQN(1) EQN(1)
i$ 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 ele-
ments in a pile. lpile left-justifies, pile and cpile cen-
ter, with different vertical spacing, and rpile right justi-
fies.
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-justified 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 fonts can be changed with prefix operators size n,
size ±n, fat, roman, italic, bold, or 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 subse-
quent 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 charac-
ter 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
Page 2 Plan 9 (printed 12/21/24)
EQN(1) EQN(1)
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 keywords to be entered as
text, and can be used to communicate with troff when all
else fails.
FILES
/sys/lib/troff/font/devutf font descriptions for PostScript
SOURCE
/sys/src/cmd/eqn
SEE ALSO
troff(1), tbl(1)
J. F. Ossanna and B. W. Kernighan, ``Troff User's Manual''.
B. W. Kernighan and L. L. Cherry, ``Typesetting
Mathematics-User's Guide'', Unix Research System
Programmer's Manual, Tenth Edition, Volume 2.
BUGS
To embolden digits, parens, etc., it is necessary to quote
them, as in `bold "12.3"'. delim off
Page 3 Plan 9 (printed 12/21/24)