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EQN(7) | Miscellaneous Information Manual | EQN(7) |
NAME
eqn — eqn language reference for mandocDESCRIPTION
The eqn language is an equation-formatting language. It is used within mdoc(7) and man(7) UNIX manual pages. It describes the structure of an equation, not its mathematical meaning. This manual 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.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-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 | "sqrt" box | 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]
- define
- Replace all occurrences of a key with a value. Its syntax
is as follows:
define key cvalcThe 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 bazcIt 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'
- gfont
- Set the default font of subsequent output. Its syntax is as
follows:
gfont fontIn mandoc, this value is discarded.
- gsize
- Set the default size of subsequent output. Its syntax is as
follows:
gsize [+|-]sizeThe size value should be an integer. If prepended by a sign, the font size is changed relative to the current size.
- set
- Set an equation mode. In mandoc, both arguments are thrown
away. Its syntax is as follows:
set key valThe 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 keyOnce invoked, the definition for key is discarded. The key is not expanded for replacements. This statement is a GNU extension.
- above
- See pile.
- bar
- Draw a line over the preceding box.
- bold
- Set the following box using bold font.
- ccol
- Like cpile, but for use in matrix.
- cpile
- Like pile, but with slightly increased vertical spacing.
- dot
- Set a single dot over the preceding box.
- dotdot
- Set two dots (dieresis) over the preceding box.
- dyad
- Set a dyad symbol (left-right arrow) over the preceding box.
- fat
- A synonym for bold.
- font
- Set the second argument using the font specified by the first argument; currently not recognized by the mandoc(1) eqn parser.
- from
- Set the following box below the preceding box, using a slightly smaller font. Used for sums, integrals, limits, and the like.
- hat
- Set a hat (circumflex) over the preceding box.
- italic
- Set the following box using italic font.
- lcol
- Like lpile, but for use in matrix.
- left
- Set the first argument as a big left delimiter before the second argument. As an optional third argument, right can follow. In that case, the fourth argument is set as a big right delimiter after the second argument.
- lpile
- Like cpile, but subequations are left-justified.
- matrix
- Followed by a list of columns enclosed in braces. All columns need to have the same number of subequations. The columns are set as a matrix. The difference compared to multiple subsequent pile operators is that in a matrix, corresponding subequations in all columns line up horizontally, while each pile does vertical spacing independently.
- over
- Set a fraction. The preceding box is the numerator, the following box is the denominator.
- pile
- Followed by a list of subequations enclosed in braces, the subequations being separated by above keywords. Sets the subequations one above the other, each of them centered. Typically used to represent vectors in coordinate representation.
- rcol
- Like rpile, but for use in matrix.
- right
- See left;
right cannot be used without
left. To set a big right delimiter without a
big left delimiter, the following construction can be used:
left "" box right delimiter
- roman
- Set the following box using the default font.
- rpile
- Like cpile, but subequations are right-justified.
- size
- Set the second argument with the font size specified by the first argument; currently ignored by mandoc(1). By prepending a plus or minus sign to the first argument, the font size can be selected relative to the current size.
- sqrt
- Set the square root of the following box.
- sub
- Set the following box as a subscript to the preceding box.
- sup
- Set the following box as a superscript to the preceding
box. As a special case, if a sup clause
immediately follows a sub clause as in
mainbox sub subbox sup supboxboth are set with respect to the same mainbox, that is, supbox is set above subbox.
- tilde
- Set a tilde over the preceding box.
- to
- Set the following box above the preceding box, using a
slightly smaller font. Used for sums and integrals and the like. As a
special case, if a to clause immediately
follows a from clause as in
mainbox from frombox to toboxboth are set below and above the same mainbox.
- under
- Underline the preceding box.
- vec
- Set a vector symbol (right arrow) over the preceding box.
mainbox
sup supbox
sub subbox
is the same as
mainbox
sup {supbox
sub
subbox}
and different from
{mainbox
sup supbox}
sub
subbox.
By contrast, over groups to the left.
In the following list, earlier operations bind more tightly than later
operations:
- dyad, vec, under, bar, tilde, hat, dot, dotdot
- fat, roman, italic, bold, size
- sub, sup
- sqrt
- over
- from, to
COMPATIBILITY
This section documents the compatibility of mandoc 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.
SEE ALSO
mandoc(1), man(7), mandoc_char(7), mdoc(7), roff(7) 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.HISTORY
The eqn utility, a preprocessor for troff, was originally written by Brian W. Kernighan and Lorinda L. Cherry in 1975. The GNU reimplementation 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
This eqn reference was written by Kristaps Dzonsons <kristaps@bsd.lv>.March 9, 2015 | Debian |