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
[CX] 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.1-2008 defers to the ISO C standard.
These functions shall compute the smallest integral value not less than x.
RETURN VALUE
[MX] 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.
[MX] If x is NaN, a NaN shall be returned.
If x is ±0 or ±Inf, x shall be returned.
ERRORS
No errors are defined.
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(3), fetestexcept(3), floor(3), isnan(3)
XBD V1_chap04(7), <math.h>
CHANGE HISTORY
First released in Issue 1. Derived from Issue 1 of the SVID.
Issue 5
The DESCRIPTION is updated to indicate how an application should check for an error. This text was previously published in the APPLICATION USAGE section.
Issue 6
The ceilf () and ceill () functions are added for alignment with the ISO/IEC 9899:1999 (“ISO C99”) standard.
The DESCRIPTION, RETURN VALUE, ERRORS, and APPLICATION USAGE sections are revised to align with the ISO/IEC 9899:1999 (“ISO C99”) standard.
IEC 60559:1989 standard floating-point extensions over the ISO/IEC 9899:1999 (“ISO C99”) standard are marked.
Issue 7
POSIX.1-2008, Technical Corrigendum 1, XSH/TC1-2008/0046 [346] is applied.