rint(3p) — Linux manual page


RINT(3P)                POSIX Programmer's Manual               RINT(3P)

PROLOG         top

       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.

NAME         top

       rint, rintf, rintl — round-to-nearest integral value

SYNOPSIS         top

       #include <math.h>

       double rint(double x);
       float rintf(float x);
       long double rintl(long double x);

DESCRIPTION         top

       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.1‐2017 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

       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         top

       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.

ERRORS         top

       No errors are defined.

       The following sections are informative.

EXAMPLES         top



       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.

RATIONALE         top




SEE ALSO         top

       abs(3p), ceil(3p), feclearexcept(3p), fetestexcept(3p),
       floor(3p), isnan(3p), nearbyint(3p)

       The Base Definitions volume of POSIX.1‐2017, Section 4.20,
       Treatment of Error Conditions for Mathematical Functions,

COPYRIGHT         top

       Portions of this text are reprinted and reproduced in electronic
       form from IEEE Std 1003.1-2017, Standard for Information
       Technology -- Portable Operating System Interface (POSIX), The
       Open Group Base Specifications Issue 7, 2018 Edition, Copyright
       (C) 2018 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 .

       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               2017                          RINT(3P)

Pages that refer to this page: math.h(0p)