NAME

eqn, neqn, checkeq − format mathematical text for nroff or troff

SYNOPSIS

eqn [ −dxy ] [ −pn ] [ −sn ] [ −fn ] [ files ]

neqn [ −dxy ] [ −pn ] [ −sn ] [ −fn ] [ files ]

checkeq [ files ]

DESCRIPTION

Eqn is a troff(1) preprocessor for typesetting mathematical text on a phototypesetter, while neqn is used for the same purpose with nroff on typewriter-like terminals.  Usage is almost always:

eqn files | troff
neqn files | nroff

or equivalent. 

If no files are specified (or if − is specified as the last argument), these programs read 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 designate two characters as delimiters; subsequent text between delimiters is then 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 the same character; the dollar sign is often used as such a delimiter.  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, new-lines, braces, double quotes, tildes, and circumflexes.  Braces {} are used for grouping; generally speaking, anywhere a single character such as 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 j makes $x sub j$, a sub k sup 2 ­produces $a sub k sup 2$, while $e sup {x sup 2 + y sup 2}$ is made with e sup {x sup 2 + y sup 2}. Fractions are made with over: a over b yields $a over b$; sqrt makes 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: $lim from {n -> inf} sum from 0 to n x sub i$ 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 $left [ x sup 2 + y sup 2 over alpha right ] ~=~ 1$.  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).  A left thing need not have a matching right thing.

Vertical piles of things are made with pile, lpile, cpile, and rpile: pile {a above b above c} ­produces $pile {a above b above c}$.  Piles may have arbitrary numbers of elements; lpile left-justifies, pile and cpile center (but 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 right-justified column. 

Diacritical marks are made with dot, dotdot, hat, tilde, bar, vec, dyad, and under: x dot = f(t) bar is $x dot = f(t) bar$, y dotdot bar ~=~ n under is $y dotdot bar ~=~ n under$, and x vec ~=~ y dyad is $x vec ~=~ y dyad$. 

Point sizes and fonts can be changed with size n or size ±n, roman, italic, bold, and font n. Point sizes 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 points 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 that will be replaced by replacement whenever it appears thereafter.  The % may be any character that does not occur in replacement.

Keywords such as sum (∑),int (∫),inf (∞),and shorthands such as >= (≥),!= (≠),and −> (→)are recognized.  Greek letters are spelled out in the desired case, as in alpha (α),or GAMMA (Γ).Mathematical words such as sin, cos, and log are made Roman automatically.  troff(1) four-character escapes such as \(dd (‡) and \(bs () may 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(1) when all else fails. Full details are given in the manual cited below.

EXAMPLE

eqn file1 | troff

would process the file "file1" with the preprocessor before formatting it with troff.

SEE ALSO

cw(1), mm(1), mmt(1), nroff(1), tbl(1), troff(1), eqnchar(5), mm(5), mv(5). 
Typesetting Mathematics−User’s Guide by B. W. Kernighan and L. L. Cherry. 

BUGS

To embolden digits, parentheses, etc., it is necessary to quote them, as in bold "12.3". 
See also BUGS under troff(1).

Version 2.4  —  May 08, 1986