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

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

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 versions <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE

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.

RETURN VALUE
       These functions return the floor of x.

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

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

ATTRIBUTES
       For an  explanation  of  the  terms  used  in  this  section,  see  at-
       tributes(7).

       +----------------------------+---------------+---------+
       |Interface                   | Attribute     | Value   |
       +----------------------------+---------------+---------+
       |floor(), floorf(), floorl() | Thread safety | MT-Safe |
       +----------------------------+---------------+---------+
CONFORMING TO
       C99, POSIX.1-2001, POSIX.1-2008.

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

NOTES
       SUSv2 and POSIX.1-2001 contain text about overflow (which might set er-
       rno 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 man-
       tissa 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
       ceil(3), lrint(3), nearbyint(3), rint(3), round(3), trunc(3)

COLOPHON
       This page is part of release 5.05 of the Linux  man-pages  project.   A
       description  of  the project, information about reporting bugs, and the
       latest    version    of    this    page,    can     be     found     at
       https://www.kernel.org/doc/man-pages/.

                                  2017-09-15                          FLOOR(3)
NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | ERRORS | ATTRIBUTES | CONFORMING TO | NOTES | SEE ALSO | COLOPHON