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NAME

       round,  roundf,  roundl  -  round  to  the  nearest  integer value in a
       floating-point format

SYNOPSIS

       #include <math.h>

       double round(double x);
       float roundf(float x);
       long double roundl(long double x);

DESCRIPTION

       These functions shall round their argument to the nearest integer value
       in  floating-point  format,  rounding  halfway  cases  away  from zero,
       regardless of the current rounding direction.

       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  rounded
       integer value.

       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 round(), roundf(), and roundl() shall return the value of the macro
       ±HUGE_VAL,  ±HUGE_VALF,  and  ±HUGE_VALL  (with  the  same  sign as x),
       respectively.

ERRORS

       These functions may fail if:

       Range Error
              The result overflows.

       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

       feclearexcept()  ,  fetestexcept()  ,  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 .