log2(3) - Linux manual page (original) (raw)

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)](../man3/log.3.html).

ERRORS top

   See [math_error(7)](../man7/math%5Ferror.7.html) 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)](../man3/log.3.html).

ATTRIBUTES top

   For an explanation of the terms used in this section, see
   [attributes(7)](../man7/attributes.7.html).
   ┌──────────────────────────────────────┬───────────────┬─────────┐
   │ **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)](../man3/cbrt.3.html), [clog2(3)](../man3/clog2.3.html), [log(3)](../man3/log.3.html), [log10(3)](../man3/log10.3.html), [sqrt(3)](../man3/sqrt.3.html)

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Linux man-pages 6.10 2024-07-23 log2(3)

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