|LOG2(3)||Linux Programmer's Manual||LOG2(3)|
NAMElog2, log2f, log2l - base-2 logarithmic function
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
DESCRIPTIONThe log2() function returns the base 2 logarithm of x.
RETURN VALUEOn success, these functions return the base 2 logarithm of x.
ERRORSSee math_error(7) for information on how to determine whether an error has occurred when calling these functions.
VERSIONSThese functions first appeared in glibc in version 2.1.
CONFORMING TOC99, POSIX.1-2001. The variant returning double also conforms to SVr4, 4.3BSD.
SEE ALSOcbrt(3), clog2(3), log(3), log10(3), sqrt(3)
COLOPHONThis 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/.