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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/local/lib/groff/site-tmac,   /usr/lo-
       cal/share/groff/site-tmac,  and finally in the standard macro directory
       /usr/local/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 <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/local/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 October 2001				EQN(1)

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

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