log2(3) Library Functions Manual log2(3) NAME log2, log2f, log2l - base-2 logarithmic function LIBRARY Math library (libm, -lm) SYNOPSIS #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)): log2(), log2f(), log2l(): _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L DESCRIPTION These functions return 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 were added in glibc 2.1. ATTRIBUTES For an explanation of the terms used in this section, see at- tributes(7). ┌────────────────────────────────────────────┬───────────────┬─────────┐ │Interface │ Attribute │ Value │ ├────────────────────────────────────────────┼───────────────┼─────────┤ │log2(), log2f(), log2l() │ Thread safety │ MT-Safe │ └────────────────────────────────────────────┴───────────────┴─────────┘ STANDARDS C99, POSIX.1-2001, POSIX.1-2008. The variant returning double also conforms to SVr4, 4.3BSD. SEE ALSO cbrt(3), clog2(3), log(3), log10(3), sqrt(3) Linux man-pages 6.03 2022-12-15 log2(3)
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