HP-UX Reference (11i v1 05/09) - 3 Library Functions N-Z (vol 7)

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rint(3M) rint(3M)

NAME

rint(), nearbyint() - round to nearest int function

SYNOPSIS

#include <math.h>

double rint(double x);

double nearbyint(double x);

DESCRIPTION

rint() and nearbyint() return the integer (represented as a double precision number) nearest x

according to the current rounding direction mode. These functions meet the requirement of the IEEE-754

standard for an operation that rounds to integer in ﬂoating-point format.

The two functions are identical except that

rint() raises the inexact exception, while nearbyint()

does not.

In the default rounding direction (round to nearest),

rint(x) is the integer nearest x with the additional

stipulation that if |

rint(x) −x|=1/2, then rint(x) is even. (The same statement applies to

nearbyint( x).)

If the current rounding direction is toward negative inﬁnity, rint() and nearbyint() are identical to

floor(). If the current rounding direction is toward positive inﬁnity, rint() and nearbyint() are

identical to

ceil().

The ISO/ANSI C committee has approved the rint() and

nearbyint() functions for inclusion in the

C9X draft standard.

To use these functions, compile either with the default

-Ae option or with the -Aa

and

-D_HPUX_SOURCE options. Make sure your program includes <

math.h>. Link in the math library by

specifying

-lm on the compiler or linker command line.

RETURN VALUE

If x is ±INFINITY, the rint() and nearbyint()

functions return ±INFINITY respectively.

If x is NaN, the

rint() and nearbyint() functions return NaN.

ERRORS

No errors are deﬁned.