EQN(7) | Miscellaneous Information Manual | EQN(7) |

`eqn`

—
eqn language reference for mandoc

`eqn`

language is an equation-formatting language. It
is used within mdoc(7) and
man(7)
UNIX manual pages. It describes the
`eqn`

language accepted by the
mandoc(1) utility, which
corresponds to the Second Edition eqn specification (see
SEE ALSO for references).
Equations within mdoc(7) or man(7) documents are enclosed by the standalone ‘.EQ’ and ‘.EN’ tags. Equations are multi-line blocks consisting of formulas and control statements.

The equation grammar is as follows, where quoted strings are case-sensitive literals in the input:

eqn : box | eqn box box : text | "{" eqn "}" | "define" text text | "ndefine" text text | "tdefine" text text | "gfont" text | "gsize" text | "set" text text | "undef" text | box pos box | box mark | "matrix" "{" [col "{" list "}" ]* | pile "{" list "}" | font box | "size" text box | "left" text eqn ["right" text] col : "lcol" | "rcol" | "ccol" | "col" text : [^space\"]+ | \".*\" pile : "lpile" | "cpile" | "rpile" | "pile" pos : "over" | "sup" | "sub" | "to" | "from" mark : "dot" | "dotdot" | "hat" | "tilde" | "vec" | "dyad" | "bar" | "under" font : "roman" | "italic" | "bold" | "fat" list : eqn | list "above" eqn space : [\^~ \t]

White-space consists of the space, tab, circumflex, and tilde characters. If within a quoted string, these space characters are retained. Quoted strings are also not scanned for replacement definitions.

The following text terms are translated into a rendered glyph, if available: alpha, beta, chi, delta, epsilon, eta, gamma, iota, kappa, lambda, mu, nu, omega, omicron, phi, pi, psi, rho, sigma, tau, theta, upsilon, xi, zeta, DELTA, GAMMA, LAMBDA, OMEGA, PHI, PI, PSI, SIGMA, THETA, UPSILON, XI, inter (intersection), union (union), prod (product), int (integral), sum (summation), grad (gradient), del (vector differential), times (multiply), cdot (centre-dot), nothing (zero-width space), approx (approximately equals), prime (prime), half (one-half), partial (partial differential), inf (infinity), >> (much greater), << (much less), -> (left arrow), <- (right arrow), += (plus-minus), != (not equal), == (equivalence), <= (less-than-equal), and >= (more-than-equal).

The following control statements are available:

`define`

- Replace all occurrences of a key with a value. Its syntax is as follows:
define
`key cvalc`The first character of the value string,

`c`, is used as the delimiter for the value`val`. This allows for arbitrary enclosure of terms (not just quotes), such asdefine`foo 'bar baz'`define`foo cbar bazc`It is an error to have an empty

`key`or`val`. Note that a quoted`key`causes errors in some`eqn`

implementations and should not be considered portable. It is not expanded for replacements. Definitions may refer to other definitions; these are evaluated recursively when text replacement occurs and not when the definition is created.Definitions can create arbitrary strings, for example, the following is a legal construction.

define foo 'define' foo bar 'baz'

Self-referencing definitions will raise an error. The

`ndefine`

statement is a synonym for`define`

, while`tdefine`

is discarded. `gfont`

- Set the default font of subsequent output. Its syntax is as follows:
gfont
`font`In mandoc, this value is discarded.

`gsize`

- Set the default size of subsequent output. Its syntax is as follows:
gsize
`size`The

`size`value should be an integer. `set`

- Set an equation mode. In mandoc, both arguments are thrown away. Its
syntax is as follows:
set
`key val`The

`key`and`val`are not expanded for replacements. This statement is a GNU extension. `undef`

- Unset a previously-defined key. Its syntax is as follows:
define
`key`Once invoked, the definition for

`key`is discarded. The`key`is not expanded for replacements. This statement is a GNU extension.

`eqn`

and the troff `eqn`

implementation (including GNU
troff).
- The text string ‘\"’ is interpreted as a literal quote in troff. In mandoc, this is interpreted as a comment.
- In troff, The circumflex and tilde white-space symbols map to fixed-width spaces. In mandoc, these characters are synonyms for the space character.
- The troff implementation of
`eqn`

allows for equation alignment with the`mark`

and`lineup`

tokens. mandoc discards these tokens. The`back`

`n`,`fwd`

`n`,`up`

`n`, and`down`

`n`commands are also ignored.

Brian W. Kernighan and
Lorinda L. Cherry, System for
Typesetting Mathematics, *Communications of the
ACM*, 18,
151–157, March,
1975.

Brian W. Kernighan and Lorinda L. Cherry, Typesetting Mathematics, User's Guide, 1976.

Brian W. Kernighan and Lorinda L. Cherry, Typesetting Mathematics, User's Guide (Second Edition), 1978.

`eqn`

reference was written by
Kristaps Dzonsons,
kristaps@bsd.lv.
September 25, 2011 | OpenBSD-5.1 |