NEARBYINT(3) Library Functions Manual NEARBYINT(3)

nearbyint nearbyintf nearbyintl — floating-point rounding functions

#include <math.h>

double nearbyint(double x);
float nearbyintf(float x);
long double nearbyintl(long double x);

The functionality described on this reference page is aligned with the ISO C standard. Any conflict between the requirements described here and the ISO C standard is unintentional. This volume of IEEE Std 1003.1-2001 (“POSIX.1”) defers to the ISO C standard.

These functions shall round their argument to an integer value in floating-point format, using the current rounding direction and without raising the inexact floating-point exception.

An application wishing to check for error situations should set errno to zero and call (FE_ALL_EXCEPT) before calling these functions. On return, if errno is non-zero or (FE_INVALID | FE_DIVBYZERO | FE_OVERFLOW | FE_UNDERFLOW) is non-zero, an error has occurred.

Upon successful completion, these functions shall return the rounded integer value.

If x is NaN, a NaN shall be returned.

If x is ±0, ±0 shall be returned.

If x is ±Inf, x shall be returned.

If the correct value would cause overflow, a range error shall occur and nearbyint (), (), and () shall return the value of the macro ±HUGE_VAL, ±HUGE_VALF, and ±HUGE_VALL (with the same sign as x), respectively.

These functions shall fail if:

[XSI] The result would cause an overflow.

If the integer expression (math_errhandling & MATH_ERRNO) is non-zero, then errno shall be set to [ERANGE]. If the integer expression (math_errhandling & MATH_ERREXCEPT) is non-zero, then the overflow floating-point exception shall be raised.

None.

On error, the expressions (math_errhandling & MATH_ERRNO) and (math_errhandling & MATH_ERREXCEPT) are independent of each other, but at least one of them must be non-zero.

None.

None.

feclearexcept(3) , fetestexcept(3) , the Base Definitions volume of IEEE Std 1003.1-2001 (“POSIX.1”), xbd_chap04(7), <math.h>

First released in Issue 6. Derived from the ISO/IEC 9899:1999 (“ISO C99”) standard.

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December 6, 2001 posix.fail