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LOG2(3) | Linux Programmer's Manual | LOG2(3) |
NAME¶
log2, log2f, log2l - base-2 logarithmic functionSYNOPSIS¶
#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)):
_XOPEN_SOURCE >= 600 ||
_ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L;
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.ERRORS¶
See math_error(7) for information on how to determine whether an error has occurred when calling these functions.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¶
cbrt(3), clog2(3), log(3), log10(3), sqrt(3)COLOPHON¶
This page is part of release 3.44 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 |