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   floor    ( 3 )

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Имя (Name)

floor, floorf, floorl - largest integral value not greater than
       argument

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Синопсис (Synopsis)

#include <math.h>

       double floor(double x);
       float floorf(float x);
       long double floorl(long double x);

       Link with -lm.

   Feature Test Macro Requirements for glibc (see
   feature_test_macros(7)):

       floorf(), floorl():
           _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
               || /* Since glibc 2.19: */ _DEFAULT_SOURCE
               || /* Glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE

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Описание (Description)

These functions return the largest integral value that is not
       greater than x.

       For example, floor(0.5) is 0.0, and floor(-0.5) is -1.0.

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Возвращаемое значение (Return value)

These functions return the floor of x.

       If x is integral, +0, -0, NaN, or an infinity, x itself is
       returned.

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Ошибки (Error)

No errors occur.  POSIX.1-2001 documents a range error for
       overflows, but see NOTES.

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Атрибуты (Attributes)

For an explanation of the terms used in this section, see
       attributes(7).

       ┌──────────────────────────────────────┬───────────────┬─────────┐
       │Interface                             │ Attribute     │ Value   │
       ├──────────────────────────────────────┼───────────────┼─────────┤
       │floor(), floorf(), floorl()           │ Thread safety │ MT-Safe │
       └──────────────────────────────────────┴───────────────┴─────────┘

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Стандарты (Conforming to)

C99, POSIX.1-2001, POSIX.1-2008.

       The variant returning double also conforms to SVr4, 4.3BSD, C89.

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Примечание (Note)

SUSv2 and POSIX.1-2001 contain text about overflow (which might
       set errno to ERANGE, or raise an FE_OVERFLOW exception).  In
       practice, the result cannot overflow on any current machine, so
       this error-handling stuff is just nonsense.  (More precisely,
       overflow can happen only when the maximum value of the exponent
       is smaller than the number of mantissa bits.  For the IEEE-754
       standard 32-bit and 64-bit floating-point numbers the maximum
       value of the exponent is 128 (respectively, 1024), and the number
       of mantissa bits is 24 (respectively, 53).)

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Смотри также (See also)

ceil(3), lrint(3), nearbyint(3), rint(3), round(3), trunc(3)

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