NAME

SYNOPSIS

DESCRIPTION

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. Thus x sub i makes $x_i$ , a sub i sup 2 produces $a_i^2$ , and e sup {x sup 2 + y sup 2} gives $e^{x^2+y^2}$ .

Fractions are made with over: a over b yields $\frac{a}{b}$ .

sqrt makes square roots: 1 over sqrt {ax sup 2 +bx+c} results in $\frac{1}{\sqrt{{\mathrm{ax}}^2+\mathrm{bx}+c}}$ .

The keywords from and to introduce lower and upper limits on arbitrary things: $\underset{n->\infty }{\lim }\sum _0^n{x}_i$ 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 $\left[x^2+\frac{y^2}{\alpha }\right]=1$ . 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} produces $\begin{array}{c}a\\ b\\ c\end{array}$ . 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 } } produces $\begin{array}{cc}{x}_i& 1\\ y_2& 2\end{array}$ . 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 $\dot{x}=f(t\overline{)}$ , y dotdot bar ~=~ n under is $\bar{\ddot{y}}=\underset{\_}{n}$ , and x vec ~=~ y dyad is $\overrightarrow{x}=\overleftrightarrow{y}$ .

Sizes and font can be changed with size n or 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 $(\sum )$ int $(\int )$ inf $(\infty )$ and shorthands like >= $(>=)$ -> $(->),$ and != $(\ne )$ 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 \(bs () 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 ALSO

NOTES