

/usr/ucb/eqn [dxy] [fn] [pn] [sn] [file] . . ./usr/ucb/neqn [file] . . .
/usr/ucb/checkeq [file] . . .
checkeq reports missing or unbalanced delimiters and .EQ/.EN pairs.
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.
The following options are available for eqn and neqn:
Subscripts and superscripts are produced with the keywords sub and sup:
x sub i
e sup {x sup 2 + y sup 2}
a sub i sup 2
Fractions are made with over:
a over b
Square roots are made with sqrt:
1 over down 10 sqrt {ax sup 2 +bx+c}
Although eqn tries to get most things at the right place on the paper, occasionally you will need to tune the output to make it just right. Local motions such as, up n, down n, fwd n and back n allow you to change the default spacing. In the previous example, a local motion, down 10, was used to get more space between the square root and the line above it.
Lower and upper limits are made with from and to:
lim from {n> inf} sum from 0 to n x sub i
Brackets and braces of the right height are made with
left and right:
left [ x sup 2 + y sup 2 over alpha right ] ~=~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 rightsideonly bracket).
Vertical piles of things are made with
pile,
lpile,
cpile,
and
rpile:
pile {a above b above c}
There can be an arbitrary number of elements in a pile. lpile leftjustifies, pile and cpile center, 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 } }
In addition, there is rcol for a rightjustified column.
Diacritical marks are made with
dot,
dotdot,
hat,
tilde,
bar,
vec,
dyad,
and
under:
x dot = f(t) bar
y dotdot bar ~=~ n under
x vec ~=~ y dyad
Size and font can be changed with size n or size ±n, roman, italic, bold, and font n. Size and font can be changed globally in a document by gsize n and gfont n, or by the commandline arguments sn and fn.
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 (), inf (), and shorthands like >= (), > (), and != () are recognized. Greek letters are spelled out in the desired case, as in alpha or GAMMA. Mathematical words like sin, cos, and log are made Roman automatically. troff(1bsd) fourcharacter escapes like \(bu () 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.
eqn file . . .  troffneqn file . . .  nroff