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 .