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EQN(1)                                                                                                EQN(1)



NAME
       eqn - format equations for troff

SYNOPSIS
       eqn [ -rvCNR ] [ -dxy ] [ -Tname ] [ -Mdir ] [ -fF ] [ -sn ] [ -pn ] [ -mn ] [ files... ]

       It is possible to have whitespace between a command line option and its parameter.

DESCRIPTION
       This  manual  page  describes  the GNU version of eqn, which is part of the groff document formatting
       system.  eqn compiles descriptions of equations embedded within troff input files into commands  that
       are understood by troff.  Normally, it should be invoked using the -e option of groff.  The syntax is
       quite compatible with Unix eqn.  The output of GNU eqn cannot be processed with Unix troff;  it  must
       be  processed  with GNU troff.  If no files are given on the command line, the standard input will be
       read.  A filename of - will cause the standard input to be read.

       eqn searches for the file eqnrc  in  the  directories  given  with  the  -M  option  first,  then  in
       /usr/lib/groff/site-tmac,  /usr/share/groff/site-tmac,  and  finally  in the standard macro directory
       /usr/share/groff/1.19.2/tmac.  If it exists, eqn will process it before the other input  files.   The
       -R option prevents this.

       GNU  eqn  does not provide the functionality of neqn: it does not support low-resolution, typewriter-like typewriterlike
       like devices (although it may work adequately for very simple input).

OPTIONS
       -dxy   Specify delimiters x and y for the left and right end,  respectively,  of  in-line  equations.
              Any delim statements in the source file overrides this.

       -C     Recognize .EQ and .EN even when followed by a character other than space or newline.

       -N     Don't allow newlines within delimiters.  This option allows eqn to recover better from missing
              closing delimiters.

       -v     Print the version number.

       -r     Only one size reduction.

       -mn    The minimum point-size is n.  eqn will not reduce the size of subscripts or superscripts to  a
              smaller size than n.

       -Tname The output is for device name.  The only effect of this is to define a macro name with a value
              of 1.  Typically eqnrc will use this to provide definitions appropriate for the output device.
              The default output device is ps.

       -Mdir  Search dir for eqnrc before the default directories.

       -R     Don't load eqnrc.

       -fF    This is equivalent to a gfont F command.

       -sn    This  is  equivalent  to a gsize n command.  This option is deprecated.  eqn will normally set
              equations at whatever the current point size is when the equation is encountered.

       -pn    This says that subscripts and superscripts should be n points  smaller  than  the  surrounding
              text.   This option is deprecated.  Normally eqn makes sets subscripts and superscripts at 70%
              of the size of the surrounding text.

USAGE
       Only the differences between GNU eqn and Unix eqn are described here.

       Most of the new features of GNU eqn are based on TeX.  There are some references to  the  differences
       between TeX and GNU eqn below; these may safely be ignored if you do not know TeX.

   Automatic spacing
       eqn gives each component of an equation a type, and adjusts the spacing between components using that
       type.  Possible types are:

              ordinary     an ordinary character such as `1' or `x';
                                                     _
              operator     a large operator such as `>';

              binary       a binary operator such as `+';

              relation     a relation such as `=';

              opening      a opening bracket such as `(';

              closing      a closing bracket such as `)';

              punctuation  a punctuation character such as `,';

              inner        a subformula contained within brackets;

              suppress     spacing that suppresses automatic spacing adjustment.

       Components of an equation get a type in one of two ways.

       type t e
              This yields an equation component that contains e but that has type t, where t is one  of  the
              types mentioned above.  For example, times is defined as

                     type "binary" \(mu

              The name of the type doesn't have to be quoted, but quoting protects from macro expansion.

       chartype t text
              Unquoted  groups  of  characters are split up into individual characters, and the type of each
              character is looked up; this changes the type that is stored for each character; it says  that
              the characters in text from now on have type t.  For example,

                     chartype "punctuation" .,;:

              would  make the characters `.,;:' have type punctuation whenever they subsequently appeared in
              an equation.  The type t can also be letter or digit; in these cases chartype changes the font
              type of the characters.  See the Fonts subsection.

   New primitives
       e1 smallover e2
              This  is  similar to over; smallover reduces the size of e1 and e2; it also puts less vertical
              space between e1 or e2 and the fraction bar.  The over primitive corresponds to the TeX  \over
              primitive in display styles; smallover corresponds to \over in non-display styles.

       vcenter e
              This  vertically  centers e about the math axis.  The math axis is the vertical position about
              which characters such as `+' and `-' are centered; also it is the vertical position  used  for
              the bar of fractions.  For example, sum is defined as

                     { type "operator" vcenter size +5 \(*S }

       e1 accent e2
              This  sets e2 as an accent over e1.  e2 is assumed to be at the correct height for a lowercase
              letter; e2 will be moved down according if e1 is taller or shorter than  a  lowercase  letter.
              For example, hat is defined as

                     accent { "^" }

              dotdot, dot, tilde, vec, and dyad are also defined using the accent primitive.

       e1 uaccent e2
              This sets e2 as an accent under e1.  e2 is assumed to be at the correct height for a character
              without a descender; e2 will be moved down if e1 has a descender.  utilde is pre-defined using
              uaccent as a tilde accent below the baseline.

       split "text"
              This has the same effect as simply

                     text

              but text is not subject to macro expansion because it is quoted; text will be split up and the
              spacing between individual characters will be adjusted.

       nosplit text
              This has the same effect as

                     "text"

              but because text is not quoted it will be subject to macro expansion; text will not  be  split
              up and the spacing between individual characters will not be adjusted.

       e opprime
              This is a variant of prime that acts as an operator on e.  It produces a different result from
              prime in a case such as A opprime sub 1: with opprime the 1 will be tucked under the prime  as
              a  subscript  to  the  A  (as is conventional in mathematical typesetting), whereas with prime
              the 1 will be a subscript to the prime character.  The precedence of opprime is  the  same  as
              that  of bar and under, which is higher than that of everything except accent and uaccent.  In
              unquoted text a ' that is not the first character will be treated like opprime.

       special text e
              This constructs a new object from e using a troff(1) macro named  text.   When  the  macro  is
              called,  the  string  0s  will  contain the output for e, and the number registers 0w, 0h, 0d,
              0skern, and 0skew will contain the width, height, depth, subscript kern, and skew of e.   (The
              subscript  kern of an object says how much a subscript on that object should be tucked in; the
              skew of an object says how far to the right of the center of the object  an  accent  over  the
              object  should be placed.)  The macro must modify 0s so that it will output the desired result
              with its origin at the current point, and increase the  current  horizontal  position  by  the
              width  of  the  object.  The number registers must also be modified so that they correspond to
              the result.

              For example, suppose you wanted a construct that `cancels' an expression by drawing a diagonal
              line through it.

                     .EQ
                     define cancel 'special Ca'
                     .EN
                     .de Ca
                     .  ds 0s \
                     \Z'\\*(0s'\
                     \v'\\n(0du'\
                     \D'l \\n(0wu -\\n(0hu-\\n(0du'\
                     \v'\\n(0hu'
                     ..

              Then you could cancel an expression e with cancel { e }

              Here's a more complicated construct that draws a box round an expression:

                     .EQ
                     define box 'special Bx'
                     .EN
                     .de Bx
                     .  ds 0s \
                     \Z'\h'1n'\\*(0s'\
                     \Z'\
                     \v'\\n(0du+1n'\
                     \D'l \\n(0wu+2n 0'\
                     \D'l 0 -\\n(0hu-\\n(0du-2n'\
                     \D'l -\\n(0wu-2n 0'\
                     \D'l 0 \\n(0hu+\\n(0du+2n'\
                     '\
                     \h'\\n(0wu+2n'
                     .  nr 0w +2n
                     .  nr 0d +1n
                     .  nr 0h +1n
                     ..

       space n
              A  positive  value  of the integer n (in hundredths of an em) sets the vertical spacing before
              the equation, a negative value sets the spacing after the equation, replacing the default val-ues. values.
              ues.  This primitive provides an interface to groff's \x escape (but with opposite sign).

              This keyword has no effect if the equation is part of a pic picture.

   Extended primitives
       col n { ... }
       ccol n { ... }
       lcol n { ... }
       rcol n { ... }
       pile n { ... }
       cpile n { ... }
       lpile n { ... }
       rpile n { ... }
              The  integer  value  n  (in  hundredths of an em) increases the vertical spacing between rows,
              using groff's \x escape.  Negative values are possible but have no effect.  If there  is  more
              than a single value given in a matrix, the biggest one is used.

   Customization
       The  appearance  of  equations is controlled by a large number of parameters.  These can be set using
       the set command.

       set p n
              This sets parameter p to value n; n is an integer.  For example,

                     set x_height 45

              says that eqn should assume an x height of 0.45 ems.

              Possible parameters are as follows.  Values are in units of hundredths of an em unless  other-wise otherwise
              wise stated.  These descriptions are intended to be expository rather than definitive.

              minimum_size
                     eqn will not set anything at a smaller point-size than this.  The value is in points.

              fat_offset
                     The fat primitive emboldens an equation by overprinting two copies of the equation hor-izontally horizontally
                     izontally offset by this amount.

              over_hang
                     A fraction bar will be longer by twice this amount than the maximum of  the  widths  of
                     the  numerator  and  denominator;  in  other  words, it will overhang the numerator and
                     denominator by at least this amount.

              accent_width
                     When bar or under is applied to a single character, the line will be this  long.   Nor-mally, Normally,
                     mally, bar or under produces a line whose length is the width of the object to which it
                     applies; in the case of a single character, this tends to produce a line that looks too
                     long.

              delimiter_factor
                     Extensible  delimiters produced with the left and right primitives will have a combined
                     height and depth of at least this many thousandths of twice the maximum amount by which
                     the sub-equation that the delimiters enclose extends away from the axis.

              delimiter_shortfall
                     Extensible  delimiters produced with the left and right primitives will have a combined
                     height and depth not less than the difference of twice the maximum amount by which  the
                     sub-equation that the delimiters enclose extends away from the axis and this amount.

              null_delimiter_space
                     This much horizontal space is inserted on each side of a fraction.

              script_space
                     The width of subscripts and superscripts is increased by this amount.

              thin_space
                     This amount of space is automatically inserted after punctuation characters.

              medium_space
                     This amount of space is automatically inserted on either side of binary operators.

              thick_space
                     This amount of space is automatically inserted on either side of relations.

              x_height
                     The height of lowercase letters without ascenders such as `x'.

              axis_height
                     The  height  above the baseline of the center of characters such as `+' and `-'.  It is
                     important that this value is correct for the font you are using.

              default_rule_thickness
                     This should set to the thickness of the \(ru character, or the thickness of  horizontal
                     lines produced with the \D escape sequence.

              num1   The over command will shift up the numerator by at least this amount.

              num2   The smallover command will shift up the numerator by at least this amount.

              denom1 The over command will shift down the denominator by at least this amount.

              denom2 The smallover command will shift down the denominator by at least this amount.

              sup1   Normally superscripts will be shifted up by at least this amount.

              sup2   Superscripts  within  superscripts or upper limits or numerators of smallover fractions
                     will be shifted up by at least this amount.  This is usually less than sup1.

              sup3   Superscripts within denominators or square roots or subscripts or lower limits will  be
                     shifted up by at least this amount.  This is usually less than sup2.

              sub1   Subscripts will normally be shifted down by at least this amount.

              sub2   When there is both a subscript and a superscript, the subscript will be shifted down by
                     at least this amount.

              sup_drop
                     The baseline of a superscript will be no more than this much amount below  the  top  of
                     the object on which the superscript is set.

              sub_drop
                     The  baseline  of a subscript will be at least this much below the bottom of the object
                     on which the subscript is set.

              big_op_spacing1
                     The baseline of an upper limit will be at least this much above the top of  the  object
                     on which the limit is set.

              big_op_spacing2
                     The baseline of a lower limit will be at least this much below the bottom of the object
                     on which the limit is set.

              big_op_spacing3
                     The bottom of an upper limit will be at least this much above the top of the object  on
                     which the limit is set.

              big_op_spacing4
                     The  top  of a lower limit will be at least this much below the bottom of the object on
                     which the limit is set.

              big_op_spacing5
                     This much vertical space will be added above and below limits.

              baseline_sep
                     The baselines of the rows in a pile or matrix will normally be this far apart.  In most
                     cases this should be equal to the sum of num1 and denom1.

              shift_down
                     The  midpoint between the top baseline and the bottom baseline in a matrix or pile will
                     be shifted down by this much from the axis.  In most cases  this  should  be  equal  to
                     axis_height.

              column_sep
                     This much space will be added between columns in a matrix.

              matrix_side_sep
                     This much space will be added at each side of a matrix.

              draw_lines
                     If this is non-zero, lines will be drawn using the \D escape sequence, rather than with
                     the \l escape sequence and the \(ru character.

              body_height
                     The amount by which the height of the equation exceeds this  will  be  added  as  extra
                     space before the line containing the equation (using \x).  The default value is 85.

              body_depth
                     The amount by which the depth of the equation exceeds this will be added as extra space
                     after the line containing the equation (using \x).  The default value is 35.

              nroff  If this is non-zero, then ndefine will behave like define and tdefine will be  ignored,
                     otherwise  tdefine  will  behave  like define and ndefine will be ignored.  The default
                     value is 0 (This is typically changed to 1 by the eqnrc file  for  the  ascii,  latin1,
                     utf8, and cp1047 devices.)

              A  more precise description of the role of many of these parameters can be found in Appendix H
              of The TeXbook.

   Macros
       Macros can take arguments.  In a macro body, $n where n is between 1 and 9, will be replaced  by  the
       n-th  argument if the macro is called with arguments; if there are fewer than n arguments, it will be
       replaced by nothing.  A word containing a left parenthesis where the part of the word before the left
       parenthesis  has  been defined using the define command will be recognized as a macro call with argu-ments; arguments;
       ments; characters following the left parenthesis up to a matching right parenthesis will  be  treated
       as comma-separated arguments; commas inside nested parentheses do not terminate an argument.

       sdefine name X anything X
              This is like the define command, but name will not be recognized if called with arguments.

       include "file"
       copy "file"
              Include  the  contents  of file (include and copy are synonyms).  Lines of file beginning with
              .EQ or .EN will be ignored.

       ifdef name X anything X
              If name has been defined by define (or has been automatically defined because name is the out-put output
              put device) process anything; otherwise ignore anything.  X can be any character not appearing
              in anything.

       undef name
              Remove definition of name, making it undefined.

       Besides the macros mentioned above, the following definitions are available: Alpha, Beta, ...,  Omega
       (this is the same as ALPHA, BETA, ..., OMEGA), ldots (three dots on the base line), and dollar.

   Fonts
       eqn normally uses at least two fonts to set an equation: an italic font for letters, and a roman font
       for everything else.  The existing gfont command changes the font that is used as  the  italic  font.
       By  default  this  is I.  The font that is used as the roman font can be changed using the new grfont
       command.

       grfont f
              Set the roman font to f.

       The italic primitive uses the current italic font set by gfont; the roman primitive uses the  current
       roman  font  set  by  grfont.  There is also a new gbfont command, which changes the font used by the
       bold primitive.  If you only use the roman, italic and bold primitives to  changes  fonts  within  an
       equation,  you can change all the fonts used by your equations just by using gfont, grfont and gbfont
       commands.

       You can control which characters are treated as letters (and therefore set in italics) by  using  the
       chartype  command described above.  A type of letter will cause a character to be set in italic type.
       A type of digit will cause a character to be set in roman type.

FILES
       /usr/share/groff/1.19.2/tmac/eqnrc  Initialization file.

BUGS
       Inline equations will be set at the point size that is current at the beginning of the input line.

SEE ALSO
       groff(1), troff(1), pic(1), groff_font(5), The TeXbook



Groff Version 1.19.2                          20 February 2005                                        EQN(1)

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