CEIL(3) Linux Programmer s Manual CEIL(3)
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);
Link with -lm.
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.1-2001 contain text about overflow (which might set errno to ERANGE, or raise an exception). In practice, the result can- not overflow on any current machine, so this error-handling stuff is just nonsense. (More precisely, overflow can happen only when the max- imum 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 SVr4, POSIX.1-2001, 4.3BSD, C89, C99. The other functions are from C99.
SEE ALSO floor(3), lrint(3), nearbyint(3), rint(3), round(3), trunc(3)