Man Linux: Main Page and Category List

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 .