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 integer 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, Copyright (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.opengroup.org/unix/online.html .