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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; 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 3.24 of the Linux man-pages project.  A
       description of the project, and information about reporting  bugs,  can
       be found at http://www.kernel.org/doc/man-pages/.

                                  2008-10-06