A length is a measure of distance. Many LaTeX commands take a length
as an argument.
A length of one inch is specified by typing 1in
or, to specify
the same length using metric units, by typing 2.54cm
.
LaTeX knows about the following common units.
in
- inches
mm
- millimeters
cm
- centimeters
pt
- points (about 1/72 inch)
em
- approximately the width of an "M"
in the current font
ex
- approximately the height of an "x"
in the current font
pc
- pica (12pt/pc)
bp
- big pt (72bp/in)
dd
- didôt (1157dd=1238pt)
cc
- cîcero (12dd/cc)
sp
- scaled point (65536sp/pt)
-1.5em
.0
by itself is not a length;
it must be specified as 0in
or 0pt
, for example.A length may also be specified by a length command. An example is
\parindent
whose value specifies the current width of the indentation
which begins paragraphs. Multiples of such length commands may be specified,
for example by writing 2.5\parindent
or -0.1\parindent
.
Some length commands are:
\parindent
- normal paragraph indentation
\baselineskip
-
normal vertical distance between lines in a paragraph
\baselinestretch
- multiplies
\baselineskip
\parskip
-
the extra vertical space between
paragraphs
\textwidth
-
the width of text on the page
\linewidth
-
width of a line in the local
environment
\textheight
- the height of text on the page
\unitlength
- units of
lenght in Picture Environment
All length commands are robust and should not be preceded by a
\protect
command.
Most lengths have a fixed value. However, LaTeX also allows for "rubber" lengths; these have a natural length plus a degree of elasticity. For example, the
\fill
length command has a natural length of zero
but is infinitely stretchable, so that a space of width \fill
will
try to stretch as much as possible. Multiplying a rubber length by a fixed
factor destroys its elasticity: 0.5\fill
becomes a rigid length
with a value of zero.
The following LaTeX commands define and manipulate the value of length commands:
\newlength
- define a new length command
\setlength
\addtolength
\settowidth
\settoheight
\settodepth