RINT(3) Linux Programmer's Manual RINT(3)
nearbyint, nearbyintf, nearbyintl, rint, rintf, rintl - round to near-
double nearbyint(double x);
float nearbyintf(float x);
long double nearbyintl(long double x);
double rint(double x);
float rintf(float x);
long double rintl(long double x);
The nearbyint functions round their argument to an integer value in
floating point format, using the current rounding direction and without
raising the inexact exception.
The rint functions do the same, but will raise the inexact exception
when the result differs in value from the argument.
The rounded integer value. If x is integral or infinite, x itself is
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 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).)
The rint() function conforms to BSD 4.3. The other functions are from
ceil(3), floor(3), lrint(3), nearbyint(3), round(3), trunc(3)