PROLOG

       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

       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

       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().  If the current rounding mode rounds toward positive infinity, then
       rint()  shall  be equivalent to ceil().  If the current rounding mode rounds towards zero,
       then rint() shall be equivalent to trunc().  If the current rounding mode  rounds  towards
       nearest, then rint() differs from round() 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.

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.   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

       No errors are defined.

       The following sections are informative.

EXAMPLES

       None.

APPLICATION USAGE

       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

       None.

FUTURE DIRECTIONS

       None.

SEE ALSO

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

       The  Base  Definitions volume of POSIX.1‐2008, Section 4.19, 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,  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 .