
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
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 ~ represents 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: $lim from {n > inf} sum from 0 to n x sub i$ 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 rightsideonly 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
leftjustifies, 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 rightjustified 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
commandline arguments −sn and −fn.
Normally subscripts and superscripts are reduced by 3 point sizes
from the previous size; this may be changed by the commandline
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)
fourcharacter 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
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 MathematicsUser’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


