geqn - Unix, Linux Command
NAME
eqn - format equations for troff
SYNOPSIS
eqn
[
-rvCNR ]
[
-d ]
[
-T ]
[
-M ]
[
-f ]
[
-s ]
[
-p ]
[
-m ] [
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/1.18.1.1/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 adequately for very simple input).
OPTIONS
| Tag | Description |
|---|
|
-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:
| Tag | Description |
|---|
|
ordinary
|
an ordinary character such as 1 or
x; |
|
operator
|
a large operator such as
S;
|
|
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.
| Tag | Description |
|---|
|
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
| Tag | Description |
|---|
|
|
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,
| Tag | Description |
|---|
|
|
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
| Tag | Description |
|---|
|
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
| Tag | Description |
|---|
|
|
{ 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
| Tag | Description |
|---|
|
|
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 stexts |
| |
This has the same effect as simply
|
|
|
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
|
|
|
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.
| Tag | Description |
|---|
|
|
.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 parameters. These can be set using
the
set command.
| Tag | Description |
|---|
|
set p n |
This sets parameter
p to value
n ; n is an integer.
For example,
| Tag | Description |
|---|
|
|
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.
| Tag | Description |
|---|
|
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.)
|
|
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.
| Tag | Description |
|---|
|
sdefine name X anything X |
| |
This is like the
define command, but
name will not be recognized if called with arguments.
|
|
include sfiles |
| |
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.
| Tag | Description |
|---|
|
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
| Tag | Description |
|---|
|
/usr/share/groff/1.18.1.1/tmac/eqnrc |
Initialization file.
|
EXAMPLES
TBD
