1EQN(7) BSD Miscellaneous Information Manual EQN(7)
2
4 eqn — eqn language reference for mandoc
5
7 The eqn language is an equation-formatting language. It is used within
8 mdoc(7) and man(7) UNIX manual pages. It describes the structure of an
9 equation, not its mathematical meaning. This manual describes the eqn
10 language accepted by the mandoc(1) utility, which corresponds to the Sec‐
11 ond Edition eqn specification (see SEE ALSO for references).
12 Equations within mdoc(7) or man(7) documents are enclosed by the stand‐
14 alone ‘.EQ’ and ‘.EN’ tags. Equations are multi-line blocks consisting
15 of formulas and control statements.
16
18 Each equation is bracketed by ‘.EQ’ and ‘.EN’ strings. Note: these are
19 not the same as roff(7) macros, and may only be invoked as ‘.EQ’.
20 The equation grammar is as follows, where quoted strings are case-sensi‐
22 tive literals in the input:
23 eqn : box | eqn box
25 box : text
26 | "{" eqn "}"
27 | "define" text text
28 | "ndefine" text text
29 | "tdefine" text text
30 | "gfont" text
31 | "gsize" text
32 | "set" text text
33 | "undef" text
34 | "sqrt" box
35 | box pos box
36 | box mark
37 | "matrix" "{" [col "{" list "}"]* "}"
38 | pile "{" list "}"
39 | font box
40 | "size" text box
41 | "left" text eqn ["right" text]
42 col : "lcol" | "rcol" | "ccol" | "col"
43 text : [^space\"]+ | \".*\"
44 pile : "lpile" | "cpile" | "rpile" | "pile"
45 pos : "over" | "sup" | "sub" | "to" | "from"
46 mark : "dot" | "dotdot" | "hat" | "tilde" | "vec"
47 | "dyad" | "bar" | "under"
48 font : "roman" | "italic" | "bold" | "fat"
49 list : eqn
50 | list "above" eqn
51 space : [\^~ \t]
52 White-space consists of the space, tab, circumflex, and tilde characters.
54 It is required to delimit tokens consisting of alphabetic characters and
55 it is ignored at other places. Braces and quotes also delimit tokens.
56 If within a quoted string, these space characters are retained. Quoted
57 strings are also not scanned for keywords, glyph names, and expansion of
58 definitions. To print a literal quote character, it can be prepended
59 with a backslash or expressed with the \(dq escape sequence.
60 Subequations can be enclosed in braces to pass them as arguments to oper‐
62 ation keywords, overriding standard operation precedence. Braces can be
63 nested. To set a brace verbatim, it needs to be enclosed in quotes.
64 The following text terms are translated into a rendered glyph, if avail‐
66 able: alpha, beta, chi, delta, epsilon, eta, gamma, iota, kappa, lambda,
67 mu, nu, omega, omicron, phi, pi, psi, rho, sigma, tau, theta, upsilon,
68 xi, zeta, DELTA, GAMMA, LAMBDA, OMEGA, PHI, PI, PSI, SIGMA, THETA,
69 UPSILON, XI, inter (intersection), union (union), prod (product), int
70 (integral), sum (summation), grad (gradient), del (vector differential),
71 times (multiply), cdot (center-dot), nothing (zero-width space), approx
72 (approximately equals), prime (prime), half (one-half), partial (partial
73 differential), inf (infinity), >> (much greater), << (much less), <-
74 (left arrow), -> (right arrow), +- (plus-minus), != (not equal), ==
75 (equivalence), <= (less-than-equal), and >= (more-than-equal). The char‐
76 acter escape sequences documented in mandoc_char(7) can be used, too.
77 The following control statements are available:
79 define Replace all occurrences of a key with a value. Its syntax is as
81 follows:
82 define key cvalc
84 The first character of the value string, c, is used as the delim‐
86 iter for the value val. This allows for arbitrary enclosure of
87 terms (not just quotes), such as
88 define foo 'bar baz'
90 define foo cbar bazc
91 It is an error to have an empty key or val. Note that a quoted
93 key causes errors in some eqn implementations and should not be
94 considered portable. It is not expanded for replacements. Defi‐
95 nitions may refer to other definitions; these are evaluated
96 recursively when text replacement occurs and not when the defini‐
97 tion is created.
98 Definitions can create arbitrary strings, for example, the fol‐
100 lowing is a legal construction.
101 define foo 'define'
103 foo bar 'baz'
104 Self-referencing definitions will raise an error. The ndefine
106 statement is a synonym for define, while tdefine is discarded.
107 gfont Set the default font of subsequent output. Its syntax is as fol‐
109 lows:
110 gfont font
112 In mandoc, this value is discarded.
114 gsize Set the default size of subsequent output. Its syntax is as fol‐
116 lows:
117 gsize [+|-]size
119 The size value should be an integer. If prepended by a sign, the
121 font size is changed relative to the current size.
122 set Set an equation mode. In mandoc, both arguments are thrown away.
124 Its syntax is as follows:
125 set key val
127 The key and val are not expanded for replacements. This state‐
129 ment is a GNU extension.
130 undef Unset a previously-defined key. Its syntax is as follows:
132 define key
134 Once invoked, the definition for key is discarded. The key is
136 not expanded for replacements. This statement is a GNU exten‐
137 sion.
138 Operation keywords have the following semantics:
140 above See pile.
142 bar Draw a line over the preceding box.
144 bold Set the following box using bold font.
146 ccol Like cpile, but for use in matrix.
148 cpile Like pile, but with slightly increased vertical spacing.
150 dot Set a single dot over the preceding box.
152 dotdot Set two dots (dieresis) over the preceding box.
154 dyad Set a dyad symbol (left-right arrow) over the preceding box.
156 fat A synonym for bold.
158 font Set the second argument using the font specified by the first
160 argument; currently not recognized by the mandoc(1) eqn parser.
161 from Set the following box below the preceding box, using a slightly
163 smaller font. Used for sums, integrals, limits, and the like.
164 hat Set a hat (circumflex) over the preceding box.
166 italic Set the following box using italic font.
168 lcol Like lpile, but for use in matrix.
170 left Set the first argument as a big left delimiter before the second
172 argument. As an optional third argument, right can follow. In
173 that case, the fourth argument is set as a big right delimiter
174 after the second argument.
175 lpile Like cpile, but subequations are left-justified.
177 matrix Followed by a list of columns enclosed in braces. All columns
179 need to have the same number of subequations. The columns are
180 set as a matrix. The difference compared to multiple subsequent
181 pile operators is that in a matrix, corresponding subequations in
182 all columns line up horizontally, while each pile does vertical
183 spacing independently.
184 over Set a fraction. The preceding box is the numerator, the follow‐
186 ing box is the denominator.
187 pile Followed by a list of subequations enclosed in braces, the sube‐
189 quations being separated by above keywords. Sets the subequa‐
190 tions one above the other, each of them centered. Typically used
191 to represent vectors in coordinate representation.
192 rcol Like rpile, but for use in matrix.
194 right See left; right cannot be used without left. To set a big right
196 delimiter without a big left delimiter, the following construc‐
197 tion can be used:
198 left "" box right delimiter
200 roman Set the following box using the default font.
202 rpile Like cpile, but subequations are right-justified.
204 size Set the second argument with the font size specified by the first
206 argument; currently ignored by mandoc(1). By prepending a plus
207 or minus sign to the first argument, the font size can be
208 selected relative to the current size.
209 sqrt Set the square root of the following box.
211 sub Set the following box as a subscript to the preceding box.
213 sup Set the following box as a superscript to the preceding box. As
215 a special case, if a sup clause immediately follows a sub clause
216 as in
217 mainbox sub subbox sup supbox
219 both are set with respect to the same mainbox, that is, supbox is
221 set above subbox.
222 tilde Set a tilde over the preceding box.
224 to Set the following box above the preceding box, using a slightly
226 smaller font. Used for sums and integrals and the like. As a
227 special case, if a to clause immediately follows a from clause as
228 in
229 mainbox from frombox to tobox
231 both are set below and above the same mainbox.
233 under Underline the preceding box.
235 vec Set a vector symbol (right arrow) over the preceding box.
237 The binary operations from, to, sub, and sup group to the right, that is,
239 mainbox sup supbox sub subbox
241 is the same as
243 mainbox sup {supbox sub subbox}
245 and different from
247 {mainbox sup supbox} sub subbox.
249 By contrast, over groups to the left.
251 In the following list, earlier operations bind more tightly than later
253 operations:
254 1. dyad, vec, under, bar, tilde, hat, dot, dotdot
256 2. fat, roman, italic, bold, size
257 3. sub, sup
258 4. sqrt
259 5. over
260 6. from, to
261
263 This section documents the compatibility of mandoc eqn and the troff eqn
264 implementation (including GNU troff).
265 - The text string ‘\"’ is interpreted as a literal quote in troff. In
267 mandoc, this is interpreted as a comment.
268 - In troff, The circumflex and tilde white-space symbols map to fixed-
269 width spaces. In mandoc, these characters are synonyms for the space
270 character.
271 - The troff implementation of eqn allows for equation alignment with
272 the mark and lineup tokens. mandoc discards these tokens. The back
273 n, fwd n, up n, and down n commands are also ignored.
274
276 mandoc(1), man(7), mandoc_char(7), mdoc(7), roff(7)
277 Brian W. Kernighan and Lorinda L. Cherry, "System for Typesetting
279 Mathematics", Communications of the ACM, 18, 151–157, March, 1975.
280 Brian W. Kernighan and Lorinda L. Cherry, Typesetting Mathematics, User's
282 Guide, 1976.
283 Brian W. Kernighan and Lorinda L. Cherry, Typesetting Mathematics, User's
285 Guide (Second Edition), 1978.
286
288 The eqn utility, a preprocessor for troff, was originally written by
289 Brian W. Kernighan and Lorinda L. Cherry in 1975. The GNU reimplementa‐
290 tion of eqn, part of the GNU troff package, was released in 1989 by James
291 Clark. The eqn component of mandoc(1) was added in 2011.
292
294 This eqn reference was written by Kristaps Dzonsons <kristaps@bsd.lv>.
295BSD June 20, 2019 BSD