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

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       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)