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/lib/groff/site-tmac,
/usr/share/groff/site-tmac, and finally in the standard macro directory
/usr/share/groff/1.19.2/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 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
deprecated. 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 `Σ';
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 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
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 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
..
space n
A positive value of the integer n (in hundredths of an em) sets
the vertical spacing 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 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 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 limits 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 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"
copy "file"
Include the contents of file (include and copy are synonyms).
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.
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 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/1.19.2/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), pic(1), groff_font(5), The_TeXbook
Groff Version 1.19.2 20 February 2005 EQN(1)