NAME
eqn — eqn language reference for mandocDESCRIPTION
The eqn language is an equationformatting 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).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’.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 cvalcdefine foo 'bar baz'define foo cbar bazc
define foo 'define' foo bar 'baz'
 gfont

Set the default font of subsequent output. Its syntax is as follows:gfont font
 gsize

Set the default size of subsequent output. Its syntax is as follows:gsize [+]size
 set

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

Unset a previouslydefined key. Its syntax is as follows:define key
 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 (leftright 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 leftjustified.
 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 rightjustified.
 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 inmainbox sub subbox sup supbox
 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 inmainbox from frombox to tobox
 under
 Underline the preceding box.
 vec
 Set a vector symbol (right arrow) over the preceding box.
mainbox sup supbox sub subbox
mainbox sup {supbox sub subbox}
{mainbox sup supbox} sub subbox.
 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 whitespace symbols map to fixedwidth 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.