Man page - log2(3)

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log2, log2f, log2l - base-2 logarithmic function

Math library ( libm , -lm )

#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

These functions return the base-2 logarithm of x .

On success, these functions return the base-2 logarithm of x .

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).

For an explanation of the terms used in this section, see attributes (7).

Image grohtml-323738-1.png

C11, POSIX.1-2008.

glibc 2.1. C99, POSIX.1-2001.

The variant returning double also conforms to SVr4, 4.3BSD.