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authorRichard M. Stallman <rms@gnu.org>1998-05-19 03:45:57 +0000
committerRichard M. Stallman <rms@gnu.org>1998-05-19 03:45:57 +0000
commita9f0a989a17f47f9d25b7a426b4e82a8ff684ee4 (patch)
treed62b5592064177c684f1509989b223623db3f24c /lispref/numbers.texi
parentc6d6572475603083762cb0155ae966de7710bb9c (diff)
*** empty log message ***
Diffstat (limited to 'lispref/numbers.texi')
-rw-r--r--lispref/numbers.texi43
1 files changed, 34 insertions, 9 deletions
diff --git a/lispref/numbers.texi b/lispref/numbers.texi
index daee3890e7..fbbdc83871 100644
--- a/lispref/numbers.texi
+++ b/lispref/numbers.texi
@@ -249,6 +249,11 @@ numbers or markers. However, it is a good idea to use @code{=} if you
can, even for comparing integers, just in case we change the
representation of integers in a future Emacs version.
+ Sometimes it is useful to compare numbers with @code{equal}; it treats
+two numbers as equal if they have the same data type (both integers, or
+both floating point) and the same value. By contrast, @code{=} can
+treat an integer and a floating point number as equal.
+
There is another wrinkle: because floating point arithmetic is not
exact, it is often a bad idea to check for equality of two floating
point values. Usually it is better to test for approximate equality.
@@ -328,7 +333,7 @@ This function returns the smallest of its arguments.
@end defun
@defun abs number
-This returns the absolute value of @var{number}.
+This function returns the absolute value of @var{number}.
@end defun
@node Numeric Conversions
@@ -357,9 +362,9 @@ This returns @var{number}, converted to an integer by rounding downward
(towards negative infinity).
If @var{divisor} is specified, @var{number} is divided by @var{divisor}
-before the floor is taken; this is the division operation that
-corresponds to @code{mod}. An @code{arith-error} results if
-@var{divisor} is 0.
+before the floor is taken; this uses the kind of division operation that
+corresponds to @code{mod}, rounding downward. An @code{arith-error}
+results if @var{divisor} is 0.
@end defun
@defun ceiling number
@@ -600,7 +605,7 @@ Conversions}.
@section Rounding Operations
@cindex rounding without conversion
-The functions @code{ffloor}, @code{fceiling}, @code{fround} and
+The functions @code{ffloor}, @code{fceiling}, @code{fround}, and
@code{ftruncate} take a floating point argument and return a floating
point result whose value is a nearby integer. @code{ffloor} returns the
nearest integer below; @code{fceiling}, the nearest integer above;
@@ -965,14 +970,34 @@ and pi/2 (exclusive) whose tangent is @var{arg}.
@end defun
@defun exp arg
-This is the exponential function; it returns @i{e} to the power
-@var{arg}. @i{e} is a fundamental mathematical constant also called the
-base of natural logarithms.
+This is the exponential function; it returns
+@tex
+$e$
+@end tex
+@ifinfo
+@i{e}
+@end ifinfo
+to the power @var{arg}.
+@tex
+$e$
+@end tex
+@ifinfo
+@i{e}
+@end ifinfo
+is a fundamental mathematical constant also called the base of natural
+logarithms.
@end defun
@defun log arg &optional base
This function returns the logarithm of @var{arg}, with base @var{base}.
-If you don't specify @var{base}, the base @var{e} is used. If @var{arg}
+If you don't specify @var{base}, the base
+@tex
+$e$
+@end tex
+@ifinfo
+@i{e}
+@end ifinfo
+is used. If @var{arg}
is negative, the result is a NaN.
@end defun