@node Floating Point Type
@subsection Floating Point Type
- Emacs supports floating point numbers (though there is a compilation
-option to disable them). The precise range of floating point numbers is
-machine-specific.
+ Floating point numbers are the computer equivalent of scientific
+notation. The precise number of significant figures and the range of
+possible exponents is machine-specific; Emacs always uses the C data
+type @code{double} to store the value.
The printed representation for floating point numbers requires either
a decimal point (with at least one digit following), an exponent, or
@cindex escape
@cindex @samp{\e}
You can express the characters Control-g, backspace, tab, newline,
-vertical tab, formfeed, return, and escape as @samp{?\a}, @samp{?\b},
-@samp{?\t}, @samp{?\n}, @samp{?\v}, @samp{?\f}, @samp{?\r}, @samp{?\e},
-respectively. Thus,
+vertical tab, formfeed, return, del, and escape as @samp{?\a},
+@samp{?\b}, @samp{?\t}, @samp{?\n}, @samp{?\v}, @samp{?\f},
+@samp{?\r}, @samp{?\d}, and @samp{?\e}, respectively. Thus,
@example
?\a @result{} 7 ; @r{@kbd{C-g}}
and the hexadecimal character code. You can use any number of hex
digits, so you can represent any character code in this way.
Thus, @samp{?\x41} for the character @kbd{A}, @samp{?\x1} for the
-character @kbd{C-a}, and @code{?\x8e0} for the character
+character @kbd{C-a}, and @code{?\x8e0} for the Latin-1 character
@iftex
@samp{@`a}.
@end iftex
@code{(@var{a} .@: @var{b})} stands for a cons cell whose @sc{car} is
the object @var{a}, and whose @sc{cdr} is the object @var{b}. Dotted
pair notation is therefore more general than list syntax. In the dotted
-pair notation, the list @samp{(1 2 3)} is written as @samp{(1 . (2 . (3
+pair notation, the list @samp{(1 2 3)} is written as @samp{(1 . (2 . (3
. nil)))}. For @code{nil}-terminated lists, you can use either
notation, but list notation is usually clearer and more convenient.
When printing a list, the dotted pair notation is only used if the
@example
(setq alist-of-colors
- '((rose . red) (lily . white) (buttercup . yellow)))
+ '((rose . red) (lily . white) (buttercup . yellow)))
@end example
@noindent
Character category tables (@pxref{Categories}).
@item
-Display Tables (@pxref{Display Tables}).
+Display tables (@pxref{Display Tables}).
@item
Syntax tables (@pxref{Syntax Tables}).