|
NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | ERRORS | ATTRIBUTES | CONFORMING TO | NOTES | SEE ALSO | COLOPHON |
|
|
|
CEIL(3) Linux Programmer's Manual CEIL(3)
ceil, ceilf, ceill - ceiling function: smallest integral value
not less than argument
#include <math.h>
double ceil(double x);
float ceilf(float x);
long double ceill(long double x);
Link with -lm.
Feature Test Macro Requirements for glibc (see
feature_test_macros(7)):
ceilf(), ceill():
_ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
|| /* Since glibc 2.19: */ _DEFAULT_SOURCE
|| /* Glibc versions <= 2.19: */ _BSD_SOURCE ||
_SVID_SOURCE
These functions return the smallest integral value that is not
less than x.
For example, ceil(0.5) is 1.0, and ceil(-0.5) is 0.0.
These functions return the ceiling of x.
If x is integral, +0, -0, NaN, or infinite, x itself is returned.
No errors occur. POSIX.1-2001 documents a range error for
overflows, but see NOTES.
For an explanation of the terms used in this section, see
attributes(7).
┌─────────────────────────┬───────────────┬─────────┐
│Interface │ Attribute │ Value │
├─────────────────────────┼───────────────┼─────────┤
│ceil(), ceilf(), ceill() │ Thread safety │ MT-Safe │
└─────────────────────────┴───────────────┴─────────┘
C99, POSIX.1-2001, POSIX.1-2008.
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).)
The integral value returned by these functions may be too large
to store in an integer type (int, long, etc.). To avoid an
overflow, which will produce undefined results, an application
should perform a range check on the returned value before
assigning it to an integer type.
floor(3), lrint(3), nearbyint(3), rint(3), round(3), trunc(3)
This page is part of release 5.10 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 CEIL(3)
Pages that refer to this page: abs(3), fabs(3), floor(3), lrint(3), lround(3), rint(3), round(3), trunc(3)
Copyright and license for this manual page
|
HTML rendering created 2020-12-21 by Michael Kerrisk, author of The Linux Programming Interface, maintainer of the Linux man-pages project. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
|