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 Wang Laboratories, Inc. C/A/T phototypesetter, while neqn is used for the same purpose with nroff(1) on typewriter-like terminals. Usage is almost always:

eqn files │ troff
neqn files │ nroff

or equivalent. 

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 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 xj, a sub k sup 2 ­produces ak2, while ex2+y2 is made with e sup {x sup 2 + y sup 2}. Fractions are made with over: a over b yieldsa over b; sqrt makes square roots: 1 over sqrt {ax sup 2+bx+c} results in 1 over √ax2+bx+c . 

The keywords from and to introduce lower and upper limits: limn→∞n∑0xi 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
⎡
⎢
⎣x2+y2 over α
⎤
⎥
⎦ = 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 a
b
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 xi
y21
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 ẋ=f(t), y dotdot bar ~=~ n under is ÿ = n, and x vec ~=~ y dyad is x⃗ = y⃡. 

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.

SEE ALSO

Typesetting Mathematics−User’s Guide by B. W. Kernighan and L. L. Cherry. 
New Graphic Symbols for EQN and NEQN by C. Scrocca. 
mm(1), mmt(1), tbl(1), troff (1), eqnchar(7), mm(7), mv(7).

BUGS

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