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EQN(1)                 BSD Reference Manual                EQN(1)


NAME
       eqn - format equations for troff

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

DESCRIPTION
       This manual page describes the GNU version of  eqn,  which
       is part of the groff document formatting system.  eqn com-
       piles 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  using  the  path
       .:/usr/share/tmac:/usr/share/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
       -C     Recognize .EQ and .EN even when followed by a char-
              acter 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 defini-
              tions  appropriate  for  the  output  device.   The
              default output device is ps.

       -Mdir  Search   dir   for   eqnrc   before   the   default



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              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 equa-
              tions 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 punctutation 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.



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EQN(1)                 BSD Reference Manual                EQN(1)


       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 charac-
              ter  is  looked  up;  this changes the type that is
              stored for each character; it says that the charac-
              ters in text from now on have type t.  For example,

                     chartype "punctuation" .,;:

              would make the characters .,;: have  type  punctua-
              tion  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  frac-
              tions.  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 { "^" }



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              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 typeset-
              ting), 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, sub-
              script 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



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              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
                     ..

   Customization
       The appearance of equations is controlled by a large  num-
       ber 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.




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              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 charac-
                                      ter,  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 pro-
                                      duced  with  the  left  and
                                      right  primitives will have
                                      a combined height and depth
                                      of at least this many thou-
                                      sandths of twice the  maxi-
                                      mum  amount  by  which  the
                                      sub-equation    that    the
                                      delimiters  enclose extends
                                      away from the axis.

              delimiter_shortfall     Extensible delimiters  pro-
                                      duced  with  the  left  and
                                      right primitives will  have



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                                      a combined height and depth
                                      not less than  the  differ-
                                      ence  of  twice the maximum
                                      amount by  which  the  sub-
                                      equation  that  the  delim-
                                      iters 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  charac-
                                      ters.

              medium_space            This  amount  of  space  is
                                      automatically  inserted  on
                                      either side of binary oper-
                                      ators.

              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  base-
                                      line of the center of char-
                                      acters 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 char-
                                      acter,  or the thickness of
                                      horizontal  lines  produced
                                      with    the    \D    escape
                                      sequence.

              num1                    The over command will shift
                                      up   the  numerator  by  at



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                                      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  super-
                                      scripts  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 denomi-
                                      nators  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 sub-
                                      script and  a  superscript,
                                      the   subscript   will   be
                                      shifted down  by  at  least
                                      this amount.

              sup_drop                The  baseline  of  a super-
                                      script 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



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                                      below  the  bottom  of  the
                                      object on  which  the  sub-
                                      script 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.




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              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 char-
                                      acter.

              body_height             The  amount  by  which  the
                                      height  of   the   equation
                                      exceeds  this will be added
                                      as extra space  before  the
                                      line  containing  the equa-
                                      tion   (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 equa-
                                      tion   (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   and    latin1
                                      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



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       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 begin-
              ning 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 any-
              thing.  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  every-
       thing  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 com-
       mands.

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

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

BUGS
       Inline  equations  will  be  set at the point size that is



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       current at the beginning of the input line.

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


















































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