1LOG2(3)                    Linux Programmer's Manual                   LOG2(3)
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NAME

6       log2, log2f, log2l - base-2 logarithmic function
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SYNOPSIS

9       #include <math.h>
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11       double log2(double x);
12       float log2f(float x);
13       long double log2l(long double x);
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15       Link with -lm.
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17   Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
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19       log2(), log2f(), log2l():
20           _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
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DESCRIPTION

23       These functions return the base 2 logarithm of x.
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RETURN VALUE

26       On success, these functions return the base 2 logarithm of x.
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28       For  special  cases,  including where x is 0, 1, negative, infinity, or
29       NaN, see log(3).
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ERRORS

32       See math_error(7) for information on how to determine whether an  error
33       has occurred when calling these functions.
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35       For  a discussion of the errors that can occur for these functions, see
36       log(3).
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VERSIONS

39       These functions first appeared in glibc in version 2.1.
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ATTRIBUTES

42       For an  explanation  of  the  terms  used  in  this  section,  see  at‐
43       tributes(7).
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45       ┌─────────────────────────┬───────────────┬─────────┐
46       │Interface                │ Attribute     │ Value   │
47       ├─────────────────────────┼───────────────┼─────────┤
48       │log2(), log2f(), log2l() │ Thread safety │ MT-Safe │
49       └─────────────────────────┴───────────────┴─────────┘

CONFORMING TO

51       C99, POSIX.1-2001, POSIX.1-2008.
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53       The variant returning double also conforms to SVr4, 4.3BSD.
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SEE ALSO

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

59       This  page  is  part of release 5.10 of the Linux man-pages project.  A
60       description of the project, information about reporting bugs,  and  the
61       latest     version     of     this    page,    can    be    found    at
62       https://www.kernel.org/doc/man-pages/.
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66                                  2017-09-15                           LOG2(3)
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