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RINT(3P) POSIX Programmer's Manual RINT(3P)
This manual page is part of the POSIX Programmer's Manual. The Linux
implementation of this interface may differ (consult the
corresponding Linux manual page for details of Linux behavior), or
the interface may not be implemented on Linux.
rint, rintf, rintl — round-to-nearest integral value
#include <math.h>
double rint(double x);
float rintf(float x);
long double rintl(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
POSIX.1‐2008 defers to the ISO C standard.
These functions shall return the integral value (represented as a
double) nearest x in the direction of the current rounding mode. The
current rounding mode is implementation-defined.
If the current rounding mode rounds toward negative infinity, then
rint() shall be equivalent to floor(3p). If the current rounding
mode rounds toward positive infinity, then rint() shall be equivalent
to ceil(3p). If the current rounding mode rounds towards zero, then
rint() shall be equivalent to trunc(3p). If the current rounding
mode rounds towards nearest, then rint() differs from round(3p) in
that halfway cases are rounded to even rather than away from zero.
These functions differ from the nearbyint(), nearbyintf(), and
nearbyintl() 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.
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. The result shall have the same sign as
x.
If x is NaN, a NaN shall be returned.
If x is ±0 or ±Inf, x shall be returned.
No errors are defined.
The following sections are informative.
None.
The integral value returned by these functions need not be
expressible as an intmax_t. The return value should be tested before
assigning it to an integer type to avoid the undefined results of an
integer overflow.
None.
None.
abs(3p), ceil(3p), feclearexcept(3p), fetestexcept(3p), floor(3p),
isnan(3p), nearbyint(3p)
The Base Definitions volume of POSIX.1‐2008, Section 4.19, Treatment
of Error Conditions for Mathematical Functions, math.h(0p)
Portions of this text are reprinted and reproduced in electronic form
from IEEE Std 1003.1, 2013 Edition, Standard for Information
Technology -- Portable Operating System Interface (POSIX), The Open
Group Base Specifications Issue 7, Copyright (C) 2013 by the
Institute of Electrical and Electronics Engineers, Inc and The Open
Group. (This is POSIX.1-2008 with the 2013 Technical Corrigendum 1
applied.) 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.unix.org/online.html .
Any typographical or formatting errors that appear in this page are
most likely to have been introduced during the conversion of the
source files to man page format. To report such errors, see
https://www.kernel.org/doc/man-pages/reporting_bugs.html .
IEEE/The Open Group 2013 RINT(3P)
Pages that refer to this page: math.h(0p)