log2, log2f, log2l - base-2 logarithmic function
#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)):
_ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
These functions return the base 2 logarithm of
On success, these functions return the base 2 logarithm of
For special cases, including where
x is 0, 1, negative, infinity, or NaN, see log(3).
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).
These functions first appeared in glibc in version 2.1.
For an explanation of the terms used in this section, see attributes(7).
|log2(), log2f(), log2l()||Thread safety||MT-Safe|
C99, POSIX.1-2001, POSIX.1-2008.
The variant returning
double also conforms to SVr4, 4.3BSD.
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