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Name
ceil, ceilf, ceill - ceiling function: smallest
integral value not less than argument
Synopsis
#include <math.h>
double ceil(double x);
float ceilf(float x);
long double ceill(long double x);
Description
These functions round x up
to the nearest integer.
Return Value
The rounded integer value. If x is integral
or infinite, x itself is returned.
Errors
No errors other than EDOM and ERANGE
can occur. If x is NaN, then NaN is returned and errno may be set to EDOM.
Notes
SUSv2 and POSIX 1003.1-2001 contain text about overflow (which might
set errno to ERANGE, or raise an 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 (resp. 1024), and the number of mantissa bits is 24 (resp. 53).)
Conforming
to
The ceil() function conforms to SVID 3, POSIX, BSD 4.3, ISO 9899. The other
functions are from C99.
See Also
floor(3)
, lrint(3)
, nearbyint(3)
, rint(3)
,
round(3)
, trunc(3)
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