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.1‐2008 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

       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

       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.1‐2008, Section 4.19, Treatment
       of Error Conditions for Mathematical Functions, math.h(0p)

COPYRIGHT         top

       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 .

       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 .

IEEE/The Open Group                 2013                            RINT(3P)