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floor(3)


NAME

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

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
   attributes(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
   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

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

COLOPHON

   This page is part of release 4.09 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/.

                              2016-03-15                          FLOOR(3)



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