RINT(P) POSIX Programmer's Manual RINT(P)NAME
rint, rintf, rintl - round-to-nearest integral value
SYNOPSIS
#include <math.h>
double rint(double x);
float rintf(float x);
long double rintl(long double x);
DESCRIPTION
These functions shall return the integral value (represented as a dou‐
ble) nearest x in the direction of the current rounding mode. The cur‐
rent rounding mode is implementation-defined.
If the current rounding mode rounds toward negative infinity, then
rint() shall be equivalent to floor() . If the current rounding mode
rounds toward positive infinity, then rint() shall be equivalent to
ceil() .
These functions differ from the nearbyint(), nearbyintf(), and nearby‐
intl() functions only in that they may raise the inexact floating-point
exception if the result differs in value from the argument.
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.
RETURN VALUE
Upon successful completion, these functions shall return the integer
(represented as a double precision number) nearest x in the direction
of the current rounding mode.
If x is NaN, a NaN shall be returned.
If x is ±0 or ±Inf, x shall be returned.
If the correct value would cause overflow, a range error shall occur
and rint(), rintf(), and rintl() shall return the value of the macro
±HUGE_VAL, ±HUGE_VALF, and ±HUGE_VALL (with the same sign as x),
respectively.
ERRORS
These functions shall fail if:
Range Error
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.
The following sections are informative.
EXAMPLES
None.
APPLICATION USAGE
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.
RATIONALE
None.
FUTURE DIRECTIONS
None.
SEE ALSOabs() , ceil() , feclearexcept() , fetestexcept() , floor() , isnan() ,
nearbyint() , the Base Definitions volume of IEEE Std 1003.1-2001, Sec‐
tion 4.18, Treatment of Error Conditions for Mathematical Functions,
<math.h>
COPYRIGHT
Portions of this text are reprinted and reproduced in electronic form
from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology
-- Portable Operating System Interface (POSIX), The Open Group Base
Specifications Issue 6, Copyright (C) 2001-2003 by the Institute of
Electrical and Electronics Engineers, Inc and The Open Group. In the
event of any discrepancy between this version and the original IEEE and
The Open Group Standard, the original IEEE and The Open Group Standard
is the referee document. The original Standard can be obtained online
at http://www.opengroup.org/unix/online.html .
IEEE/The Open Group 2003 RINT(P)
