-.\" $Id: eqn.7,v 1.3 2011/07/17 14:08:49 kristaps Exp $
+.\" $Id: eqn.7,v 1.39 2020/01/10 11:55:04 schwarze Exp $
.\"
.\" Copyright (c) 2011 Kristaps Dzonsons <kristaps@bsd.lv>
+.\" Copyright (c) 2014 Ingo Schwarze <schwarze@openbsd.org>
.\"
.\" Permission to use, copy, modify, and distribute this software for any
.\" purpose with or without fee is hereby granted, provided that the above
.\" ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
.\" OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
.\"
-.Dd $Mdocdate: July 17 2011 $
+.Dd $Mdocdate: January 10 2020 $
.Dt EQN 7
.Os
.Sh NAME
.Sh DESCRIPTION
The
.Nm eqn
-language is a equation-formatting language.
+language is an equation-formatting language.
It is used within
.Xr mdoc 7
and
.Xr man 7
.Ux
manual pages.
-This manual describes the subset of the
+It describes the
+.Em structure
+of an equation, not its mathematical meaning.
+This manual describes the
.Nm
language accepted by the
.Xr mandoc 1
-utility.
+utility, which corresponds to the Second Edition
+.Nm
+specification (see
+.Sx SEE ALSO
+for references).
.Pp
-Equations within
-.Xr mdoc 7
-or
-.Xr man 7
-documents are enclosed by the standalone
-.Sq \&.EQ
-and
-.Sq \&.EN
-tags.
-Equations are multi-line blocks consisting of formulas and control
-statements.
-.Sh EQUATION STRUCTURE
-Each equation is bracketed by
-.Sq \&.EQ
-and
-.Sq \&.EN
-strings.
-.Em Note :
-these are not the same as
-.Xr roff 7
-macros, and may only be invoked as
-.Sq \&.EQ .
+An equation starts with an input line containing exactly the characters
+.Sq \&.EQ ,
+may contain multiple input lines, and ends with an input line
+containing exactly the characters
+.Sq \&.EN .
+Equivalently, an equation can be given in the middle of a single
+text input line by surrounding it with the equation delimiters
+defined with the
+.Cm delim
+statement.
.Pp
-The equation grammar is as follows:
+The equation grammar is as follows, where quoted strings are
+case-sensitive literals in the input:
.Bd -literal -offset indent
eqn : box | eqn box
box : text
- | DEFINE text text
- | SET text text
- | UNDEF text
-text : TEXT
+ | \(dq{\(dq eqn \(dq}\(dq
+ | \(dqdefine\(dq text text
+ | \(dqndefine\(dq text text
+ | \(dqtdefine\(dq text text
+ | \(dqgfont\(dq text
+ | \(dqgsize\(dq text
+ | \(dqset\(dq text text
+ | \(dqundef\(dq text
+ | \(dqsqrt\(dq box
+ | box pos box
+ | box mark
+ | \(dqmatrix\(dq \(dq{\(dq [col \(dq{\(dq list \(dq}\(dq]* \(dq}\(dq
+ | pile \(dq{\(dq list \(dq}\(dq
+ | font box
+ | \(dqsize\(dq text box
+ | \(dqleft\(dq text eqn [\(dqright\(dq text]
+col : \(dqlcol\(dq | \(dqrcol\(dq | \(dqccol\(dq | \(dqcol\(dq
+text : [^space\e\(dq]+ | \e\(dq.*\e\(dq
+pile : \(dqlpile\(dq | \(dqcpile\(dq | \(dqrpile\(dq | \(dqpile\(dq
+pos : \(dqover\(dq | \(dqsup\(dq | \(dqsub\(dq | \(dqto\(dq | \(dqfrom\(dq
+mark : \(dqdot\(dq | \(dqdotdot\(dq | \(dqhat\(dq | \(dqtilde\(dq | \(dqvec\(dq
+ | \(dqdyad\(dq | \(dqbar\(dq | \(dqunder\(dq
+font : \(dqroman\(dq | \(dqitalic\(dq | \(dqbold\(dq | \(dqfat\(dq
+list : eqn
+ | list \(dqabove\(dq eqn
+space : [\e^~ \et]
.Ed
.Pp
-Data in TEXT form is a non-empty sequence of non-space characters or a
-non-empty quoted string.
-White-space (and enclosing literal quote pairs) is thrown away and
-productions may not be broken by newlines.
+White-space consists of the space, tab, circumflex, and tilde
+characters.
+It is required to delimit tokens consisting of alphabetic characters
+and it is ignored at other places.
+Braces and quotes also delimit tokens.
+If within a quoted string, these space characters are retained.
+Quoted strings are also not scanned for keywords, glyph names,
+and expansion of definitions.
+To print a literal quote character, it can be prepended with a
+backslash or expressed with the \e(dq escape sequence.
+.Pp
+Subequations can be enclosed in braces to pass them as arguments
+to operation keywords, overriding standard operation precedence.
+Braces can be nested.
+To set a brace verbatim, it needs to be enclosed in quotes.
+.Pp
+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 (center-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 character escape sequences documented in
+.Xr mandoc_char 7
+can be used, too.
.Pp
The following control statements are available:
.Bl -tag -width Ds
.It Cm define
-Replace all occurances of a key with a value.
+Replace all occurrences of a key with a value.
Its syntax is as follows:
.Pp
-.D1 define Ar key val
+.D1 Cm define Ar key cvalc
+.Pp
+The first character of the value string,
+.Ar c ,
+is used as the delimiter for the value
+.Ar val .
+This allows for arbitrary enclosure of terms (not just quotes), such as
+.Pp
+.D1 Cm define Ar foo \(aqbar baz\(aq
+.D1 Cm define Ar foo cbar bazc
.Pp
It is an error to have an empty
-.Ar key or
-.Ar value .
+.Ar key
+or
+.Ar val .
Note that a quoted
.Ar key
causes errors in some
.Nm
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.
+.Pp
+Definitions can create arbitrary strings, for example, the following is
+a legal construction.
+.Bd -literal -offset indent
+define foo \(aqdefine\(aq
+foo bar \(aqbaz\(aq
+.Ed
+.Pp
+Self-referencing definitions will raise an error.
+The
+.Cm ndefine
+statement is a synonym for
+.Cm define ,
+while
+.Cm tdefine
+is discarded.
+.It Cm delim
+This statement takes a string argument consisting of two bytes,
+to be used as the opening and closing delimiters for equations
+in the middle of text input lines.
+Conventionally, the dollar sign is used for both delimiters,
+as follows:
+.Bd -literal -offset indent
+\&.EQ
+delim $$
+\&.EN
+An equation like $sin pi = 0$ can now be entered
+in the middle of a text input line.
+.Ed
+.Pp
+The special statement
+.Cm delim off
+temporarily disables previously declared delimiters and
+.Cm delim on
+reenables them.
+.It Cm gfont
+Set the default font of subsequent output.
+Its syntax is as follows:
+.Pp
+.D1 Cm gfont Ar font
+.Pp
+In mandoc, this value is discarded.
+.It Cm gsize
+Set the default size of subsequent output.
+Its syntax is as follows:
+.Pp
+.D1 Cm gsize Oo +|\- Oc Ns Ar size
+.Pp
+The
+.Ar size
+value should be an integer.
+If prepended by a sign,
+the font size is changed relative to the current size.
.It Cm set
-Set an equation mode.
-Both arguments are thrown away.
+Set an equation mode.
+In mandoc, both arguments are thrown away.
+Its syntax is as follows:
+.Pp
+.D1 Cm set Ar key val
+.Pp
+The
+.Ar key
+and
+.Ar val
+are not expanded for replacements.
+This statement is a GNU extension.
.It Cm undef
Unset a previously-defined key.
Its syntax is as follows:
.Pp
-.D1 define Ar key
+.D1 Cm define Ar key
.Pp
Once invoked, the definition for
.Ar key
is discarded.
+The
+.Ar key
+is not expanded for replacements.
+This statement is a GNU extension.
+.El
+.Pp
+Operation keywords have the following semantics:
+.Bl -tag -width Ds
+.It Cm above
+See
+.Cm pile .
+.It Cm bar
+Draw a line over the preceding box.
+.It Cm bold
+Set the following box using bold font.
+.It Cm ccol
+Like
+.Cm cpile ,
+but for use in
+.Cm matrix .
+.It Cm cpile
+Like
+.Cm pile ,
+but with slightly increased vertical spacing.
+.It Cm dot
+Set a single dot over the preceding box.
+.It Cm dotdot
+Set two dots (dieresis) over the preceding box.
+.It Cm dyad
+Set a dyad symbol (left-right arrow) over the preceding box.
+.It Cm fat
+A synonym for
+.Cm bold .
+.It Cm font
+Set the second argument using the font specified by the first argument;
+currently not recognized by the
+.Xr mandoc 1
+.Nm
+parser.
+.It Cm from
+Set the following box below the preceding box,
+using a slightly smaller font.
+Used for sums, integrals, limits, and the like.
+.It Cm hat
+Set a hat (circumflex) over the preceding box.
+.It Cm italic
+Set the following box using italic font.
+.It Cm lcol
+Like
+.Cm lpile ,
+but for use in
+.Cm matrix .
+.It Cm left
+Set the first argument as a big left delimiter before the second argument.
+As an optional third argument,
+.Cm right
+can follow.
+In that case, the fourth argument is set as a big right delimiter after
+the second argument.
+.It Cm lpile
+Like
+.Cm cpile ,
+but subequations are left-justified.
+.It Cm 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
+.Cm pile
+operators is that in a
+.Cm matrix ,
+corresponding subequations in all columns line up horizontally,
+while each
+.Cm pile
+does vertical spacing independently.
+.It Cm over
+Set a fraction.
+The preceding box is the numerator, the following box is the denominator.
+.It Cm pile
+Followed by a list of subequations enclosed in braces,
+the subequations being separated by
+.Cm above
+keywords.
+Sets the subequations one above the other, each of them centered.
+Typically used to represent vectors in coordinate representation.
+.It Cm rcol
+Like
+.Cm rpile ,
+but for use in
+.Cm matrix .
+.It Cm right
+See
+.Cm left ;
+.Cm right
+cannot be used without
+.Cm left .
+To set a big right delimiter without a big left delimiter, the following
+construction can be used:
+.Pp
+.D1 Cm left No \(dq\(dq Ar box Cm right Ar delimiter
+.It Cm roman
+Set the following box using the default font.
+.It Cm rpile
+Like
+.Cm cpile ,
+but subequations are right-justified.
+.It Cm size
+Set the second argument with the font size specified by the first
+argument; currently ignored by
+.Xr mandoc 1 .
+By prepending a plus or minus sign to the first argument,
+the font size can be selected relative to the current size.
+.It Cm sqrt
+Set the square root of the following box.
+.It Cm sub
+Set the following box as a subscript to the preceding box.
+.It Cm sup
+Set the following box as a superscript to the preceding box.
+As a special case, if a
+.Cm sup
+clause immediately follows a
+.Cm sub
+clause as in
+.Pp
+.D1 Ar mainbox Cm sub Ar subbox Cm sup Ar supbox
+.Pp
+both are set with respect to the same
+.Ar mainbox ,
+that is,
+.Ar supbox
+is set above
+.Ar subbox .
+.It Cm tilde
+Set a tilde over the preceding box.
+.It Cm 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
+.Cm to
+clause immediately follows a
+.Cm from
+clause as in
+.Pp
+.D1 Ar mainbox Cm from Ar frombox Cm to Ar tobox
+.Pp
+both are set below and above the same
+.Ar mainbox .
+.It Cm under
+Underline the preceding box.
+.It Cm vec
+Set a vector symbol (right arrow) over the preceding box.
+.El
+.Pp
+The binary operations
+.Cm from ,
+.Cm to ,
+.Cm sub ,
+and
+.Cm sup
+group to the right, that is,
+.Pp
+.D1 Ar mainbox Cm sup Ar supbox Cm sub Ar subbox
+.Pp
+is the same as
+.Pp
+.D1 Ar mainbox Cm sup Brq Ar supbox Cm sub Ar subbox
+.Pp
+and different from
+.Pp
+.D1 Bro Ar mainbox Cm sup Ar supbox Brc Cm sub Ar subbox .
+.Pp
+By contrast,
+.Cm over
+groups to the left.
+.Pp
+In the following list, earlier operations bind more tightly than
+later operations:
+.Pp
+.Bl -enum -compact
+.It
+.Cm dyad ,
+.Cm vec ,
+.Cm under ,
+.Cm bar ,
+.Cm tilde ,
+.Cm hat ,
+.Cm dot ,
+.Cm dotdot
+.It
+.Cm fat ,
+.Cm roman ,
+.Cm italic ,
+.Cm bold ,
+.Cm size
+.It
+.Cm sub ,
+.Cm sup
+.It
+.Cm sqrt
+.It
+.Cm over
+.It
+.Cm from ,
+.Cm to
+.El
+.Sh COMPATIBILITY
+This section documents the compatibility of mandoc
+.Nm
+and the troff
+.Nm
+implementation (including GNU troff).
+.Pp
+.Bl -dash -compact
+.It
+The text string
+.Sq \e\(dq
+is interpreted as a literal quote in troff.
+In mandoc, this is interpreted as a comment.
+.It
+In troff, The circumflex and tilde white-space symbols map to
+fixed-width spaces.
+In mandoc, these characters are synonyms for the space character.
+.It
+The troff implementation of
+.Nm
+allows for equation alignment with the
+.Cm mark
+and
+.Cm lineup
+tokens.
+mandoc discards these tokens.
+The
+.Cm back Ar n ,
+.Cm fwd Ar n ,
+.Cm up Ar n ,
+and
+.Cm down Ar n
+commands are also ignored.
.El
.Sh SEE ALSO
.Xr mandoc 1 ,
.%T System for Typesetting Mathematics
.%J Communications of the ACM
.%V 18
-.%P 151\(en157
+.%P pp. 151\(en157
.%D March, 1975
.Re
-.\" .Sh HISTORY
-.\" The tbl utility, a preprocessor for troff, was originally written by M.
-.\" E. Lesk at Bell Labs in 1975.
-.\" The GNU reimplementation of tbl, part of the groff package, was released
-.\" in 1990 by James Clark.
-.\" A standalone tbl implementation was written by Kristaps Dzonsons in
-.\" 2010.
-.\" This formed the basis of the implementation that is part of the
-.\" .Xr mandoc 1
-.\" utility.
+.Rs
+.%A Brian W. Kernighan
+.%A Lorinda L. Cherry
+.%T Typesetting Mathematics, User's Guide
+.%D 1976
+.Re
+.Rs
+.%A Brian W. Kernighan
+.%A Lorinda L. Cherry
+.%T Typesetting Mathematics, User's Guide (Second Edition)
+.%D 1978
+.Re
+.Sh 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
+.Xr mandoc 1
+was added in 2011.
.Sh AUTHORS
-This partial
+This
.Nm
reference was written by
-.An Kristaps Dzonsons Aq kristaps@bsd.lv .
+.An Kristaps Dzonsons Aq Mt kristaps@bsd.lv .
git.ckatri.com / mandoc.git / blobdiff