CEIL
Section: POSIX Programmer's Manual (3P)
Updated: 2017
Page Index
PROLOG
This manual page is part of the POSIX Programmer's Manual.
The Linux implementation of this interface may differ (consult
the corresponding Linux manual page for details of Linux behavior),
or the interface may not be implemented on Linux.
NAME
ceil,
ceilf,
ceill
--- ceiling value function
SYNOPSIS
#include <math.h>
double ceil(double x);
float ceilf(float x);
long double ceill(long double x);
DESCRIPTION
The functionality described on this reference page is aligned with the
ISO C standard. Any conflict between the requirements described here and the
ISO C standard is unintentional. This volume of POSIX.1-2017 defers to the ISO C standard.
These functions shall compute the smallest integral value not less than
x.
RETURN VALUE
The result shall have the same sign as
x.
Upon successful completion,
ceil(),
ceilf(),
and
ceill()
shall return the smallest integral value not less than
x,
expressed as a type
double,
float,
or
long double,
respectively.
If
x
is NaN, a NaN shall be returned.
If
x
is ±0 or ±Inf,
x
shall be returned.
ERRORS
No errors are defined.
The following sections are informative.
EXAMPLES
None.
APPLICATION USAGE
The integral value returned by these functions need not be expressible
as an
intmax_t.
The return value should be tested before assigning it to an integer
type to avoid the undefined results of an integer overflow.
These functions may raise the inexact floating-point exception if the
result differs in value from the argument.
RATIONALE
None.
FUTURE DIRECTIONS
None.
SEE ALSO
feclearexcept(),
fetestexcept(),
floor(),
isnan()
The Base Definitions volume of POSIX.1-2017,
Section 4.20, Treatment of Error Conditions for Mathematical Functions,
<math.h>
COPYRIGHT
Portions of this text are reprinted and reproduced in electronic form
from IEEE Std 1003.1-2017, Standard for Information Technology
-- Portable Operating System Interface (POSIX), The Open Group Base
Specifications Issue 7, 2018 Edition,
Copyright (C) 2018 by the Institute of
Electrical and Electronics Engineers, Inc and The Open Group.
In the event of any discrepancy between this version and the original IEEE and
The Open Group Standard, the original IEEE and The Open Group Standard
is the referee document. The original Standard can be obtained online at
http://www.opengroup.org/unix/online.html .
Any typographical or formatting errors that appear
in this page are most likely
to have been introduced during the conversion of the source files to
man page format. To report such errors, see
https://www.kernel.org/doc/man-pages/reporting_bugs.html .