log2(3) — Linux manual page

log2(3)                  Library Functions Manual                 log2(3)

NAME         top

       log2, log2f, log2l - base-2 logarithmic function

LIBRARY         top

       Math library (libm, -lm)

SYNOPSIS         top

       #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         top

       These functions return the base-2 logarithm of x.

RETURN VALUE         top

       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         top

       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).

ATTRIBUTES         top

       For an explanation of the terms used in this section, see
       attributes(7).
       ┌──────────────────────────────────────┬───────────────┬─────────┐
       │ Interface                            │ Attribute     │ Value   │
       ├──────────────────────────────────────┼───────────────┼─────────┤
       │ log2(), log2f(), log2l()             │ Thread safety │ MT-Safe │
       └──────────────────────────────────────┴───────────────┴─────────┘

STANDARDS         top

       C11, POSIX.1-2008.

HISTORY         top

       glibc 2.1.  C99, POSIX.1-2001.

       The variant returning double also conforms to SVr4, 4.3BSD.

SEE ALSO         top

       cbrt(3), clog2(3), log(3), log10(3), sqrt(3)

COLOPHON         top

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Linux man-pages 6.15            2025-05-17                        log2(3)

Pages that refer to this page: log10(3),  log(3)

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