log2(3) Library Functions Manual log2(3) log2, log2f, log2l - 2 (libm -lm) #include double log2(double x); float log2f(float x); long double log2l(long double x); glibc ( feature_test_macros(7)): log2(), log2f(), log2l(): _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L 2 x. 2 x. x 0 1 NaN log(3). math_error(7) . log(3). attributes(7). +------------+------------------------------------+--------------------+ || | | +------------+------------------------------------+--------------------+ |log2(), | | MT-Safe | |log2f(), | | | |log2l() | | | +------------+------------------------------------+--------------------+ C11, POSIX.1-2008. glibc 2.1. C99 POSIX.1-2001. double SVr4 4.3BSD. cbrt(3), clog2(3), log(3), log10(3), sqrt(3) 3 . . : . 6.18 8 2026 log2(3)