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

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
       lround, lroundf, lroundl - round to nearest integer value
SYNOPSIS
       #include <math.h>
       long lround(double x);
       long lroundf(float x);
       long lroundl(long double x);

DESCRIPTION
       These functions shall round  their  argument  to  the  nearest  integer
       value, 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 domain error shall occur and an unspecified value is
       returned.
       If x is +Inf, a domain error shall occur and an  unspecified  value  is
       returned.
       If  x  is  -Inf, a domain error shall occur and an unspecified value is
       returned.
       If the correct value is positive and too large to represent as a  long,
       a domain error shall occur and an unspecified value is returned.
       If  the correct value is negative and too large to represent as a long,
       a domain error shall occur and an unspecified value is returned.
ERRORS
       These functions shall fail if:
       Domain Error
              The x argument is NaN or +-Inf, or the correct value is not rep-
              resentable as an integer.
       If  the integer expression (math_errhandling & MATH_ERRNO) is non-zero,
       then  errno  shall  be  set  to  [EDOM].  If  the  integer   expression
       (math_errhandling  &  MATH_ERREXCEPT)  is  non-zero,  then  the invalid
       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
       These functions differ from the lrint() functions in the default round-
       ing  direction, with the lround() functions rounding halfway cases away
       from zero and needing not to raise the inexact floating-point exception
       for  non-integer arguments that round to within the range of the return
       type.
FUTURE DIRECTIONS
       None.
SEE ALSO
       feclearexcept(), fetestexcept(), llround(), 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 .

IEEE/The Open Group                  2003                           LROUND(3P)