(BSD System Compatibility)


eqn, neqn, checkeq -- (BSD) typeset mathematics


   /usr/ucb/eqn [-dxy] [-fn] [-pn] [-sn] [file] . . .

/usr/ucb/neqn [file] . . .

/usr/ucb/checkeq [file] . . .


The eqn and neqn commands are language processors to assist in describing equations. eqn is a preprocessor for troff(1bsd) and is intended for devices that can print troff's output. neqn is a preprocessor for nroff(1bsd) and is intended for use with terminals.

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:

Set 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.

Change font to n globally in the document. The font can also be changed globally in the body of the document by using the gfont directive.

Reduce subscripts and superscripts by n point sizes from the prevailing size. In the absence of the -p option, subscripts and superscripts are reduced by 3 point sizes from the prevailing size.

Set equations in point size n globally in the document. The point size can also be changed globally in the body of the document by using the gsize directive.

Prepare output for device dev. If no -T option is present, eqn looks at the environment variable TYPESETTER to see what the intended output device is. If no such variable is found in the environment, a system-dependent default device is assumed. Not available using neqn.


eqn language

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. Tilde (~) represents a full space in the output, circumflex (^) half as much.

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 right-side-only 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 left-justifies, 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 right-justified 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 command-line 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 (GREEK CAPITAL LETTER SIGMA), inf (INFINITY), and shorthands like >= (GREATER THAN OR EQUAL TO), -> (->), and != (NOT EQUAL TO) 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) four-character escapes like \(bu (BULLET) 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.


eqnchar(5bsd), ms(5bsd), tbl(1bsd), troff(1bsd)


To embolden digits, parens, and so on, it is necessary to quote them, as in bold "12.3".


   eqn file . . . | troff

neqn file . . . | nroff

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UnixWare 7 Release 7.1.4 - 25 April 2004