ROUND

NAME

round, roundf, roundl - round to nearest integer, away from zero

SYNOPSIS

#include <math.h>

double round(double x);


float roundf(float x);


long double roundl(long double x);

DESCRIPTION

These functions round fIxfP to the nearest integer, but round halfway cases away from zero (regardless of the current rounding direction), instead of to the nearest even integer like rint().

RETURN VALUE

The rounded integer value. If fIxfP is integral or infinite, fIxfP itself is returned.

ERRORS

No errors other than EDOM and ERANGE can occur. If fIxfP is NaN, then NaN is returned and errno may be set to EDOM.

NOTES

POSIX 1003.1-2001 contains 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

C99.