nearbyint, nearbyintf, nearbyintl - floating-point rounding functions
double nearbyint(double x);
float nearbyintf(float x);
long double nearbyintl(long double x);
[CX] 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 POSIX.1-2008 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 feclearexcept(FE_ALL_EXCEPT) before calling these functions. On return, if errno is non-zero or fetestexcept(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.
[MX] 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.
[XSI] If the correct value would cause overflow, a range error shall occur and nearbyint(), nearbyintf(), and nearbyintl() 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:
- Range Error
- [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.
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.
feclearexcept , fetestexcept
XBD Treatment of Error Conditions for Mathematical Functions , <math.h>
First released in Issue 6. Derived from the ISO/IEC 9899:1999 standard.
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