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# NetBSD 6.1.5 - man page for eqn (netbsd section 1)

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 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/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 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  new-
line.

-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  super-
scripts 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	appropri-
ate 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 nor-
mally 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 sur-
rounding 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 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 char-
acter; 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 corre-
sponds 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 posi-
tion about which characters such as +' and -' are centered; also it is the verti-
cal 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  '  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 regis-
ters 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
..

space n
A  positive value of the integer n (in hundredths of an em) sets the vertical spac-
ing before the equation, a negative value sets  the  spacing  after  the	equation,
replacing  the  default values.  This primitive provides an interface to groff's \x
escape (but with opposite sign).

This keyword has no effect if the equation is part of a pic picture.

Extended primitives
col n { ... }
ccol n { ... }
lcol n { ... }
rcol n { ... }
pile n { ... }
cpile n { ... }
lpile n { ... }
rpile n { ... }
The integer value n (in hundredths of an em) increases the vertical spacing between
rows,  using  groff's  \x escape.  Negative values are possible but have no effect.
If there is more than a single value given in a matrix, the biggest one is used.

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  maxi-
mum  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
-'.  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 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 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  argu-
ments; 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"
copy "file"
Include the contents of file (include and copy are synonyms).  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 anything.  X  can  be  any
character not appearing in anything.

undef name
Remove definition of name, making it undefined.

Besides	the macros mentioned above, the following definitions are available: Alpha, Beta,
..., Omega (this is the same as ALPHA, BETA, ..., OMEGA), ldots (three dots  on	the  base
line), and dollar.

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  primi-
tives to changes fonts within an equation, you can change all the fonts used by your equa-
tions 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.

Groff Version 1.19.2			 February 6, 2006				   EQN(1)`