EQN(1) User Commands EQN(1)

NAME

eqn, neqn, checkeq - typeset mathematics test

SYNOPSIS

eqn [-d xy] [ -f n] [-p n] [ -s n] [file]...


neqn [file]...


checkeq [file]...

DESCRIPTION

eqn and neqn are language processors to assist in describing
equations. eqn is a preprocessor for troff(1) and is intended for
devices that can print troff's output. neqn is a preprocessor for
nroff(1) and is intended for use with terminals. Usage is almost
always:

example% eqn file ... | troff
example% neqn file ... | nroff


If no files are specified, eqn and neqn read from the standard input.
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, and so on. It is also possible to set two
characters as ``delimiters''; subsequent text between delimiters is
also treated as eqn input.


checkeq reports missing or unbalanced delimiters and .EQ/.EN pairs.

OPTIONS

The following options are supported:

-dxy
Sets equation delimiters set to characters x and y with the
command-line argument. The more common way to do this is
with delim xy between .EQ and .EN. The left and right
delimiters may be identical. Delimiters are turned off by
delim off appearing in the text. All text that is neither
between delimiters nor between .EQ and .EN is passed through
untouched.


-fn
Changes font to n globally in the document. The font can
also be changed globally in the body of the document by
using the gfont n directive, where n is the font
specification.


-pn
Reduces subscripts and superscripts by n point sizes from
the previous size. In the absence of the -p option,
subscripts and superscripts are reduced by 3 point sizes
from the previous size.


-sn
Changes point size to n globally in the document. The point
size can also be changed globally in the body of the
document by using the gsize n directive, where n is the
point size.

OPERANDS

The following operands are supported:

file
The nroff or troff file processed by eqn or neqn.

EQN LANGUAGE

The nroff version of this description depicts the output of neqn to
the terminal screen exactly as neqn is able to display it. To see an
accurate depiction of the output, view the printed version of this
page.


Tokens within eqn are separated by braces, double quotes, tildes,
circumflexes, SPACE, TAB, or NEWLINE characters. 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. A tilde (~) represents a full SPACE in the output; a
circumflex (^) half as much.

Subscripts and superscripts:

These are produced with the keywords sub and sup.

x sub i
makes x_i


a sub i sup 2
produces a_i^2


e sup {x sup 2 + y sup 2}
gives e^(x^2+y^2)


Fractions:

Fractions are made with over.

a over b
yields a/b


Square Roots:

These are made with sqrt

1 over sqrt {ax sup 2 +bx+c}

results in 1/<sqrt>(ax^2 + bx + c)


Limits:

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

makes lim_(n -> <infinity>) <sum>_0^n x_i


Brackets and Braces:

Left and right brackets, braces, and the like, of the right
height are made with left and right.

left [ x sup 2 + y sup 2 over alpha right ] ~=~1

produces [x^2 + (y^2)/<alpha>] = 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:

Vertical piles of things are made with pile, lpile, cpile, and
rpile.

pile {a above b above c}
produces a b 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:

Matrices are made with matrix.

matrix { lcol { x sub i above y sub 2 } ccol { 1 above 2 } }

produces (x_i y_2) (1 2)


In addition, there is rcol for a right-justified column.


Diacritical marks:

Diacritical marks are made with dot, dotdot, hat, tilde, bar,
vec, dyad, and under.

x dot = f(t) bar
is x. = f (t)-


y dotdot bar ~=~ n under
is y"- = n_


x vec ~=~ y dyad
is x-> = y<->


Sizes and Fonts:

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.


Successive display arguments:

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:

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 and Shorthands:

Keywords like sum int inf and shorthands like >= -> and != are
recognized.


Greek letters:

Greek letters are spelled out in the desired case, as in alpha or
GAMMA.


Mathematical words:

Mathematical words like sin, cos, and log are made Roman
automatically.


troff(1) four-character escapes like +o (+o) 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.

SEE ALSO

nroff(1), tbl(1), troff(1), attributes(7), ms(7)

BUGS

To embolden characters such as digits and parentheses, it is
necessary to quote them, as in `bold "12.3"'.

July 12, 2002 EQN(1)