NAME

log2, log2f, log2l - base-2 logarithmic function

SYNOPSIS

#include <math.h>

double log2(double x);

float log2f(float x);

long double log2l(long double x);

Link with -lm.

Feature Test Macro Requirements for glibc (see feature_test_macros(7)):

log2(), log2f(), log2l(): _XOPEN_SOURCE >= 600 || _ISOC99_SOURCE; or cc -std=c99

DESCRIPTION

The log2() function returns the base 2 logarithm of x.

ERRORS

The log2() function can return the following error:

EDOM

The argument x is negative.

ERANGE

The argument x is zero. The log of zero is not defined (minus infinity).

CONFORMING TO

SVr4, 4.3BSD, C89. The float and long double variants are C99 requirements.

SEE ALSO

cbrt(3), clog2(3), sqrt(3)

COLOPHON

This page is part of release 2.80 of the Linux man-pages project. A description of the project, and information about reporting bugs, can be found at http://www.kernel.org/doc/man-pages/.