I would appreciate any donations. Wishlist or send e-mail type donations to maekawa AT daemon-systems.org.

Thank you.


EQN(7)                 Miscellaneous Information Manual                 EQN(7)

NAME
     eqn - eqn language reference for mandoc

DESCRIPTION
     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]

     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 \(dq escape sequence.

     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.

     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 mandoc_char(7) can be used,
     too.

     The following control statements are available:

     define  Replace all occurrences of a key with a value.  Its syntax is as
             follows:

                   define key cvalc

             The 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 as

                   define foo 'bar baz'
                   define foo cbar bazc

             It 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'

             Self-referencing definitions will raise an error.  The ndefine
             statement is a synonym for define, while tdefine is discarded.

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

                   gfont font

             In mandoc, this value is discarded.

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

                   gsize [+|-]size

             The 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 val

             The 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 key

             Once invoked, the definition for key is discarded.  The key is
             not expanded for replacements.  This statement is a GNU
             extension.

     Operation keywords have the following semantics:

     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 supbox

             both 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 tobox

             both are set below and above the same mainbox.

     under   Underline the preceding box.

     vec     Set a vector symbol (right arrow) over the preceding box.

     The binary operations from, to, sub, and sup group to the right, that is,

           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:

     1.   dyad, vec, under, bar, tilde, hat, dot, dotdot
     2.   fat, roman, italic, bold, size
     3.   sub, sup
     4.   sqrt
     5.   over
     6.   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>.

NetBSD 8.0                      March 30, 2015                      NetBSD 8.0