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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():
           _BSD_SOURCE || _SVID_SOURCE || _XOPEN_SOURCE >= 600 || _ISOC99_SOURCE ||
           _POSIX_C_SOURCE >= 200112L;
           or cc -std=c99

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.

CONFORMING TO

       C99, POSIX.1-2001.  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 3.35 of the Linux man-pages project.  A  description  of  the
       project,  and information about reporting bugs, can be found at http://man7.org/linux/man-
       pages/.

                                            2010-09-20                                   FLOOR(3)