| NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | ERRORS | CONFORMING TO | NOTES | SEE ALSO | COLOPHON | The Linux Programming Interface |
FLOOR(3) Linux Programmer's Manual FLOOR(3)
floor, floorf, floorl - largest integral value not greater than argument
#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
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.
These functions return the floor of x.
If x is integral, +0, -0, NaN, or an infinity, x itself is returned.
No errors occur. POSIX.1-2001 documents a range error for overflows, but see
NOTES.
C99, POSIX.1-2001. The variant returning double also conforms to SVr4,
4.3BSD, C89.
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).)
ceil(3), lrint(3), nearbyint(3), rint(3), round(3), trunc(3)
This page is part of release 3.32 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/.
2010-09-20 FLOOR(3)
HTML rendering created 2010-12-03 by Michael Kerrisk, author of The Linux Programming Interface