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EQN(1)                      General Commands Manual                     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  equa-
       tions  embedded  within troff input files into commands that are under-
       stood 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  ade-
       quately for very simple input).

OPTIONS
       -dxy   Specify  delimiters  x and y for the left and right end, respec-
              tively, 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 depre-
              cated.  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 the summation operator;

       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  exam-
              ple, times is defined as

                     type "binary" \(mu

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

       chartype t text
              Unquoted groups of characters are split up into individual char-
              acters,  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 charac-
              ters 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 mathemati-
              cal 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  every-
              thing  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
                     ..

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

       set p n
              This sets parameter p to value n ; n is an integer.   For  exam-
              ple,

                     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 hun-
              dredths 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  equa-
                                      tion 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 maxi-
                                      mum 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 opera-
                                      tors.

              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 cor-
                                      rect for the font you are using.

              default_rule_thickness  This should set to the thickness of  the
                                      \(ru character, or the thickness of hor-
                                      izontal  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 lim-
                                      its 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  typi-
                                      cally 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 parame-
              ters 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; char-
       acters following the left parenthesis up to a matching right  parenthe-
       sis  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



Groff Version 1.18.1             05 March 2005                          EQN(1)