floorl(3) — Linux manual page


FLOOR(3)                  Linux Programmer's Manual                 FLOOR(3)

NAME         top

       floor, floorf, floorl - largest integral value not greater than argu‐

SYNOPSIS         top

       #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 versions <= 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.  POSIX.1-2001 documents a range error for overflows,
       but see NOTES.

ATTRIBUTES         top

       For an explanation of the terms used in this section, see

       │Interface                   Attribute     Value   │
       │floor(), floorf(), floorl() │ Thread safety │ MT-Safe │

CONFORMING TO         top

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

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

NOTES         top

       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).)

SEE ALSO         top

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

COLOPHON         top

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       description of the project, information about reporting bugs, and the
       latest version of this page, can be found at

                                 2017-09-15                         FLOOR(3)