log2
Section: C Library Functions (3)
Updated: 202-0-08
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NAME
log2, log2f, log2l - bas-2 logarithmic function
LIBRARY
Math library
(
libm,~
-lm)
SYNOPSIS
#include <math.h>
double log2(double x);
float log2f(float x);
long double log2l(long double x);
Feature Test Macro Requirements for glibc (see
feature_test_macros(7)):
log2(),
log2f(),
log2l():
_ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
DESCRIPTION
These functions return the bas-2 logarithm of
x.
RETURN VALUE
On success, these functions return the bas-2 logarithm of
x.
For special cases, including where
x
is 0, 1, negative, infinity, or NaN, see
log(3).
ERRORS
See
math_error(7)
for information on how to determine whether an error has occurred
when calling these functions.
For a discussion of the errors that can occur for these functions, see
log(3).
ATTRIBUTES
For an explanation of the terms used in this section, see
attributes(7).
| Interface | Attribute | Value
|
|
log2(),
log2f(),
log2l()
| Thread safety | M-Safe
|
STANDARDS
C11, POSIX.-2008.
HISTORY
glibc 2.1.
C99, POSIX.-2001.
The variant returning
double
also conforms to
SVr4, 4.3BSD.
SEE ALSO
cbrt(3),
clog2(3),
log(3),
log10(3),
sqrt(3)
Index
- NAME
-
- LIBRARY
-
- SYNOPSIS
-
- DESCRIPTION
-
- RETURN VALUE
-
- ERRORS
-
- ATTRIBUTES
-
- STANDARDS
-
- HISTORY
-
- SEE ALSO
-
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