term% cat index.txt EQN(1) General Commands Manual EQN(1)
delim $$
NAME
eqn - typeset mathematics
SYNOPSIS
eqn [ option ... ] [ file ... ]
DESCRIPTION
Eqn is a troff(1) preprocessor for typesetting mathematics on a type‐
setter. Usage is almost always
eqn file ... | troff
If no files are specified, eqn reads from the standard input. Eqn pre‐
pares output for the typesetter named in the -Tdest option (default
-Tutf; see troff(1)). When run with other preprocessor filters, eqn
usually comes last.
A line beginning with .EQ marks the start of an equation; the end of an
equation is marked by a line beginning with .EN. Neither of these
lines is altered, so they may be defined in macro packages to get cen‐
tering, numbering, etc. It is also possible to set two characters as
`delimiters'; text between delimiters is also eqn input. Delimiters
may be set to characters x and y with the option -dxy or (more com‐
monly) with delim xy between .EQ and .EN. Left and right delimiters
may be identical. (They are customarily taken to be $font L "$$" )$.
Delimiters are turned off by All text that is neither between delim‐
iters nor between .EQ and .EN is passed through untouched.
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 could appear, a
complicated construction enclosed in braces may be used instead. Tilde
represents a full space in the output, circumflex half as much.
Subscripts and superscripts are produced with the keywords sub and sup.
Thus makes $x sub i$, produces $a sub i sup 2$, and gives $e sup {x sup
2 + y sup 2}$.
Over makes fractions: yields $a over b$.
Sqrt produces square roots: 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
Left and right brackets, braces, etc., of the right height are made
with left and right: 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:
produces $pile {a above b above c}$. There can be an arbitrary number
of elements in a pile. lpile left-justifies, pile and cpile center,
with different vertical spacing, and rpile right justifies.
Matrices are made with matrix: 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: is $x sub 0 sup prime = f(t) bar + g(t)
under$, and 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 subsequent equations.
Shorthands may be defined or existing keywords redefined with define:
thing replacement defines a new token called thing which will be re‐
placed by replacement whenever it appears thereafter. The may be any
character that does not occur in
Keywords like ( sum ), ( int ), ( inf ), and shorthands like (>=),
(->), and ( != ) are recognized. Greek letters are spelled out in the
desired case, as in or Mathematical words like are made Roman automati‐
cally. Troff(1) four-character escapes like (☜) 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 commu‐
nicate 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, Vol‐
ume 2.
BUGS
To embolden digits, parens, etc., it is necessary to quote them, as in
delim off
EQN(1)