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 -> oo) E_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)/a] = 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(5), ms(5)

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)