logb(3) Library Functions Manual logb(3) logb, logbf, logbl - LIBRARY Math library (libm, -lm) #include double logb(double x); float logbf(float x); long double logbl(long double x); glibc (. feature_test_macros(7)): logb(): _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L || _XOPEN_SOURCE >= 500 || /* glibc 2.19: */ _DEFAULT_SOURCE || /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE logbf(), logbl(): _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L || /* glibc 2.19: */ _DEFAULT_SOURCE || /* Glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE x . FLT_RADIX, , . FLT_RADIX 2, logb(x) floor(log2(x)) (, , ). x , logb() x , . x. x NaN, NaN. x , , -HUGE_VAL, -HUGE_VALF -HUGE_VALL, . x , . math_error(7), , . : : x 0 (FE_DIVBYZERO). errno. attributes(7). +----------------------------+----------------------------------------------------------+--------------------------+ | | | | +----------------------------+----------------------------------------------------------+--------------------------+ |logb(), logbf(), logbl() | | MT-Safe | +----------------------------+----------------------------------------------------------+--------------------------+ C11, POSIX.1-2008. C99, POSIX.1-2001. logb() 4.3BSD (see IEEE.3 in the 4.3BSD manual). . ilogb(3), log(3) Artyom Kunyov , Azamat Hackimov , Dmitry Bolkhovskikh , Katrin Kutepova , Konstantin Shvaykovskiy , Yuri Kozlov ; GNU 3 , . . , , . Linux man-pages 6.06 31 2023 . logb(3)