EQN(7) DragonFly Miscellaneous Information Manual EQN(7)## NAME

eqn-- eqn language reference for mandoc## DESCRIPTION

Theeqnlanguage is an equation-formatting language. It is used within mdoc(7) and man(7) UNIX manual pages. It describes thestructureof an equation, not its mathematical meaning. This manual describes theeqnlanguage accepted by the mandoc(1) utility, which corresponds to the Sec- ond Edition eqn specification (seeSEEALSOfor references). Equations within mdoc(7) or man(7) documents are enclosed by the stand- alone `.EQ' and `.EN' tags. Equations are multi-line blocks consisting of formulas and control statements.## EQUATION STRUCTURE

Each equation is bracketed by `.EQ' and `.EN' strings.Note: these are not the same as roff(7) macros, and may only be invoked as `.EQ'. The equation grammar is as follows, where quoted strings are case-sensi- tive 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 avail- able: 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:defineReplace all occurrences of a key with a value. Its syntax is as follows: definekeycvalcThe first character of the value string,c, is used as the delim- iter for the valueval. This allows for arbitrary enclosure of terms (not just quotes), such as definefoo'barbaz'definefoocbarbazcIt is an error to have an emptykeyorval. Note that a quotedkeycauses errors in someeqnimplementations and should not be considered portable. It is not expanded for replacements. Defi- nitions may refer to other definitions; these are evaluated recursively when text replacement occurs and not when the defini- tion is created. Definitions can create arbitrary strings, for example, the fol- lowing is a legal construction. define foo 'define' foo bar 'baz' Self-referencing definitions will raise an error. Thendefinestatement is a synonym fordefine, whiletdefineis discarded.gfontSet the default font of subsequent output. Its syntax is as fol- lows: gfontfontIn mandoc, this value is discarded.gsizeSet the default size of subsequent output. Its syntax is as fol- lows: gsizesizeThesizevalue should be an integer.setSet an equation mode. In mandoc, both arguments are thrown away. Its syntax is as follows: setkeyvalThekeyandvalare not expanded for replacements. This state- ment is a GNU extension.undefUnset a previously-defined key. Its syntax is as follows: definekeyOnce invoked, the definition forkeyis discarded. Thekeyis not expanded for replacements. This statement is a GNU exten- sion.## COMPATIBILITY

This section documents the compatibility of mandoceqnand the troffeqnimplementation (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 ofeqnallows for equation alignment with themarkandlineuptokens. mandoc discards these tokens. Thebackn,fwdn,upn, anddownncommands are also ignored.## SEE ALSO

mandoc(1), man(7), mandoc_char(7), mdoc(7), roff(7) Brian W. Kernighan and Lorinda L. Cherry, "System for Typesetting Mathematics",CommunicationsoftheACM, 18, 151-157, March, 1975. Brian W. Kernighan and Lorinda L. Cherry,TypesettingMathematics,User'sGuide, 1976. Brian W. Kernighan and Lorinda L. Cherry,TypesettingMathematics,User'sGuide(SecondEdition), 1978.## HISTORY

The eqn utility, a preprocessor for troff, was originally written by Brian W. Kernighan and Lorinda L. Cherry in 1975. The GNU reimplementa- tion of eqn, part of the GNU troff package, was released in 1989 by James Clark. The eqn component of mandoc(1) was added in 2011.## AUTHORS

Thiseqnreference was written by Kristaps Dzonsons <kristaps@bsd.lv>. DragonFly 4.1 July 13, 2013 DragonFly 4.1