Provided by: groff-base_1.18.1.1-20_i386 bug

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/1.18.1/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  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 Ξ£;

       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 β€β€™ 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 β€˜cancels’ an
              expression by drawing a diagonal line through it.

                     .EQ
                     define cancel β€β€™special Caβ€β€™
                     .EN
                     .de Ca
                     .ds 0s \Zβ€β€™\\*(0sβ€β€™\vβ€β€™\\n(0duβ€β€™\Dβ€β€™l \\n(0wu -\\n(0hu-\\n(0duβ€β€™\vβ€β€™\\n(0huβ€β€™
                     ..

              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 β€β€™special Bxβ€β€™
                     .EN
                     .de Bx
                     .ds 0s \Zβ€β€™\hβ€β€™1nβ€β€™\\*(0sβ€β€™\
                     \Zβ€β€™\vβ€β€™\\n(0du+1nβ€β€™\Dβ€β€™l \\n(0wu+2n 0β€β€™\Dβ€β€™l 0 -\\n(0hu-\\n(0du-2nβ€β€™\
                     \Dβ€β€™l -\\n(0wu-2n 0β€β€™\Dβ€β€™l 0 \\n(0hu+\\n(0du+2nβ€β€™β€β€™\hβ€β€™\\n(0wu+2nβ€β€™
                     .nr 0w +2n
                     .nr 0d +1n
                     .nr 0h +1n
                     ..

   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 otherwise 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  horizontally  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.
                                      Normally,  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 βˆ’.
                                      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  arguments;
       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"
              Include the contents of file.  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  output  device)  process  anything;
              otherwise ignore anything.  X can be any character not appearing
              in anything.

   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/1.18.1/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), groff_font(5), The TeXbook