geqn


EQN(1)                                                                  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

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/1.18.1.1/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     Donâ€™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.

-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 Î£;

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 doesnâ€™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-

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 â€â€™ 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 â€˜cancelsâ€™ an
expression by drawing a diagonal line through it.

.EQ
define cancel â€â€™special Caâ€â€™
.EN
.de Ca
.ds 0s \Zâ€â€™\\*(0sâ€â€™\vâ€â€™\\n(0duâ€â€™\Dâ€â€™l \\n(0wu -\\n(0hu-\\n(0duâ€â€™\vâ€â€™\\n(0huâ€â€™
..

Then you could cancel an expression e with cancel { e }

Hereâ€™s a more complicated construct that draws a  box  round  an
expression:

.EQ
define box â€â€™special Bxâ€â€™
.EN
.de Bx
.ds 0s \Zâ€â€™\hâ€â€™1nâ€â€™\\*(0sâ€â€™\
\Zâ€â€™\vâ€â€™\\n(0du+1nâ€â€™\Dâ€â€™l \\n(0wu+2n 0â€â€™\Dâ€â€™l 0 -\\n(0hu-\\n(0du-2nâ€â€™\
\Dâ€â€™l -\\n(0wu-2n 0â€â€™\Dâ€â€™l 0 \\n(0hu+\\n(0du+2nâ€â€™â€â€™\hâ€â€™\\n(0wu+2nâ€â€™
.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 âˆ’.
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/1.18.1.1/tmac/eqnrc
Initialization file.



BUGS

       Inline equations will be set at the point size that is current  at  the
beginning of the input line.



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