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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 in-
       put 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/share/tmac, /usr/share/tmac, and finally  in
       the  standard  macro directory /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 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 <Sigma>;

       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 ac-
	      cording 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 ac-
	      cent 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 ex-
	      pansion; text will not be	split up and the spacing between indi-
	      vidual 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 op-
	      prime 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 ob-
	      ject  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 nu-
				      merator 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 es-
				      cape sequence.

	      num1		      The over command will shift up  the  nu-
				      merator 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 de-
				      nominator	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 up-
				      per 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 su-
				      perscript, 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 ob-
				      ject 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 de-
				      vices.)

	      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 re-
       placed by nothing.  A word containing a left parenthesis	where the part
       of  the word before the left parenthesis	has been defined using the de-
       fine command will be recognized as a macro call with arguments; charac-
       ters  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 us-
       ing the new grfont command.

       grfont f
	      Set the roman font to f.

       The italic primitive uses the current italic font set by	gfont; the ro-
       man primitive uses the current roman font set by	grfont.	 There is also
       a new gbfont command, which changes the font used by  the  bold	primi-
       tive.  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/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 1.19		11 October 2002				EQN(1)

NAME | SYNOPSIS | DESCRIPTION | OPTIONS | USAGE | FILES | BUGS | SEE ALSO

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