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.1‐2017 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().
       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.1‐2017, Section 4.20, Treatment of Error Conditions for Mathematical
       Functions, <math.h>

COPYRIGHT

       Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1-2017, 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(3POSIX)