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

floor(3) Library Functions Manual floor(3)

NAME top

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

LIBRARY top

   Math library (_libm_, _-lm_)

SYNOPSIS top

   **#include <math.h>**

   **double floor(double** _x_**);**
   **float floorf(float** _x_**);**
   **long double floorl(long double** _x_**);**

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

DESCRIPTION top

   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.

RETURN VALUE top

   These functions return the floor of _x_.

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

ERRORS top

   No errors occur.

ATTRIBUTES top

   For an explanation of the terms used in this section, see
   [attributes(7)](../man7/attributes.7.html).
   ┌──────────────────────────────────────┬───────────────┬─────────┐
   │ **Interface** │ **Attribute** │ **Value** │
   ├──────────────────────────────────────┼───────────────┼─────────┤
   │ **floor**(), **floorf**(), **floorl**()          │ Thread safety │ MT-Safe │
   └──────────────────────────────────────┴───────────────┴─────────┘

STANDARDS top

   C11, POSIX.1-2008.

HISTORY top

   C99, POSIX.1-2001.

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

   SUSv2 and POSIX.1-2001 contain text about overflow (which might
   set _[errno](../man3/errno.3.html)_ to **ERANGE**, or raise an **FE_OVERFLOW** exception).  In
   practice, the result cannot overflow on any current machine, so
   this error-handling stuff was 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 127 (respectively, 1023), and the number
   of mantissa bits including the implicit bit is 24 (respectively,
   53).)  This was removed in POSIX.1-2008.

SEE ALSO top

   [ceil(3)](../man3/ceil.3.html), [lrint(3)](../man3/lrint.3.html), [nearbyint(3)](../man3/nearbyint.3.html), [rint(3)](../man3/rint.3.html), [round(3)](../man3/round.3.html), [trunc(3)](../man3/trunc.3.html)

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

Pages that refer to this page:abs(3), ceil(3), fabs(3), lrint(3), lround(3), rint(3), round(3), roundup(3), trunc(3)