NAME

       isunordered - test if arguments are unordered

SYNOPSIS

       #include <math.h>

       int isunordered(real-floating x, real-floating y);

DESCRIPTION

       The isunordered() macro shall determine whether its arguments are unordered.

RETURN VALUE

       Upon  successful  completion,  the isunordered() macro shall return 1 if its arguments are
       unordered, and 0 otherwise.

       If x or y is NaN, 0 shall be returned.

ERRORS

       No errors are defined.

       The following sections are informative.

EXAMPLES

       None.

APPLICATION USAGE

       The relational and equality operators support the usual mathematical relationships between
       numeric  values.  For any ordered pair of numeric values, exactly one of the relationships
       (less, greater, and equal) is true. Relational operators may raise the  invalid  floating-
       point  exception  when argument values are NaNs. For a NaN and a numeric value, or for two
       NaNs, just the unordered relationship is true. This macro is a  quiet  (non-floating-point
       exception raising) version of a relational operator. It facilitates writing efficient code
       that accounts for NaNs without suffering the  invalid  floating-point  exception.  In  the
       SYNOPSIS  section,  real-floating  indicates  that  the argument shall be an expression of
       real-floating type.

RATIONALE

       None.

FUTURE DIRECTIONS

       None.

SEE ALSO

       isgreater() , isgreaterequal() , isless() , islessequal() ,  islessgreater()  ,  the  Base
       Definitions volume of IEEE Std 1003.1-2001, <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 .