Originální popis anglicky:
ceil, ceilf, ceill - ceiling function: smallest integral value not less than
argument
Návod, kniha: Linux Programmer's Manual
#include <math.h>
double ceil(double x);
float ceilf(float x);
long double ceill(long double x);
Link with -lm.
These functions round
x up to the nearest integer.
The rounded integer value. If
x is integral or infinite,
x itself
is returned.
No errors other than EDOM and ERANGE can occur. If
x is NaN, then NaN is
returned and
errno may be set to EDOM.
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).)
The
ceil() function conforms to SVID 3, POSIX, BSD 4.3, ISO 9899. The
other functions are from C99.
floor(3),
lrint(3),
nearbyint(3),
rint(3),
round(3),
trunc(3)
