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floor(3)

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
       attributes(7).

       allbox;  lbw27  lb  lb  l  l  l.  Interface Attribute Value T{ floor(),
       floorf(), floorl() T}   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  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 5.02 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)
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