LOG2(3) - man page online | library functions

Base-2 logarithmic function.

LOG2(3)                             Linux Programmer's Manual                             LOG2(3)

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 || _POSIX_C_SOURCE >= 200112L; or cc -std=c99
DESCRIPTION These functions return the base 2 logarithm of x.
RETURN VALUE 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).
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).
VERSIONS These functions first appeared in glibc in version 2.1.
ATTRIBUTES For an explanation of the terms used in this section, see attributes(7). ┌─────────────────────────┬───────────────┬─────────┐ │Interface │ Attribute │ Value │ ├─────────────────────────┼───────────────┼─────────┤ │log2(), log2f(), log2l() │ Thread safety │ MT-Safe │ └─────────────────────────┴───────────────┴─────────┘
CONFORMING TO C99, POSIX.1-2001, POSIX.1-2008. The variant returning double also conforms to SVr4, 4.3BSD.
SEE ALSO cbrt(3), clog2(3), log(3), log10(3), sqrt(3)
COLOPHON This page is part of release 4.04 of the Linux man-pages project. A description of the project, information about reporting bugs, and the latest version of this page, can be found at
2015-04-19 LOG2(3)
This manual Reference Other manuals
log2(3) referred by graphops(3tcl) | log(3) | log10(3)
refer to attributes(7) | cbrt(3) | clog2(3) | feature_test_macros(7) | log(3) | log10(3) | math_error(7) | sqrt(3)