NAME
eqn, neqn, checkeq - typeset mathematics

SYNOPSIS
eqn [ -dxy ] [ -pn ] [ -sn ] [ -fn ] [ file ] ...
checkeq [ file ] ...

DESCRIPTION
Eqn is a troff(1) preprocessor for typesetting mathematics on a
Graphic Systems phototypesetter, neqn on terminals. Usage is
almost always

eqn file ... | troff
neqn file ... | nroff

If no files are specified, these programs 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, etc. It is also possible to
set two characters as ‘delimiters’; subsequent text between
delimiters is also treated as eqn input. Delimiters may be set to
characters x and y with the command-line argument -dxy or (more
commonly) with ‘delim xy’ between .EQ and .EN. The left and right
delimiters may be identical. Delimiters are turned off by ‘delim
off’. All text that is neither between delimiters nor between .EQ
and .EN is passed through untouched.

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

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.

Matrices are made with matrix. In addition, there is rcol for a
right-justified column.

Sizes and fonts can be changed with size n, size +n, 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.

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: 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 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) 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
communicate with troff when all else fails. See the hard copy of
this "man" page (in the MachTen User’s Reference Manual) for
examples. See also the papers referenced below in the MachTen Text
Processing manual.

SEE ALSO
troff(1), tbl(1), ms(7), eqnchar(7)
B. W. Kernighan and L. L. Cherry, Typesetting Mathematics-User’s
Guide (see MachTen Text Processing manual)
J. F. Ossanna, NROFF/TROFF User’s Manual (see MachTen Text
Processing manual)

BUGS
To embolden digits, parens, etc., it is necessary to quote them, as
in ‘bold "12.3"’.