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



PROLOG
       This  manual  page is part of the POSIX Programmer's Manual.  The Linux implementation of this interface may differ (con-
       sult 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
       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().

       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.

       If x is NaN, a NaN shall be returned.

       If x is +-0 or +-Inf, x shall be returned.

       If  the  correct  value would cause overflow, a range error shall occur and rint(), rintf(), and rintl() shall return the
       value of the macro +-HUGE_VAL, +-HUGE_VALF, and +-HUGE_VALL (with the same sign as x), respectively.

ERRORS
       These functions shall fail if:

       Range Error
              The result would cause an overflow.

       If the integer expression (math_errhandling & MATH_ERRNO) is non-zero, then errno shall be set to [ERANGE]. If the  inte-
       ger  expression  (math_errhandling  &  MATH_ERREXCEPT)  is  non-zero, then the overflow floating-point exception shall be
       raised.


       The following sections are informative.

EXAMPLES
       None.

APPLICATION USAGE
       On error, the expressions (math_errhandling & MATH_ERRNO) and (math_errhandling & MATH_ERREXCEPT) are independent of each
       other, but at least one of them must be non-zero.

RATIONALE
       None.

FUTURE DIRECTIONS
       None.

SEE ALSO
       abs(),   ceil(),  feclearexcept(),  fetestexcept(),  floor(),  isnan(),  nearbyint(),  the  Base  Definitions  volume  of
       IEEE Std 1003.1-2001, Section 4.18, 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, 2003  Edition,  Standard  for
       Information  Technology -- Portable Operating System Interface (POSIX), The Open Group Base Specifications Issue 6, Copy-
       right (C) 2001-2003 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.open-
       group.org/unix/online.html .



IEEE/The Open Group                                           2003                                                      RINT(3P)