table of contents
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():
or cc -std=c99
DESCRIPTION¶
The log2() function returns 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.
CONFORMING TO¶
C99, POSIX.1-2001. The variant returning double also conforms to SVr4, 4.3BSD.
SEE ALSO¶
COLOPHON¶
This page is part of release 3.53 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/.
2010-09-12 |