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 FLOOR(3)