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ISUNORDERED(3P)            POSIX Programmer's Manual           ISUNORDERED(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
       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 excep-
       tion 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 expres-
       sion of real-floating type.
RATIONALE
       None.
FUTURE DIRECTIONS
       None.
SEE ALSO
       isgreater(),   isgreaterequal(),   isless(),   islessequal(),   isless-
       greater(),   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 .

IEEE/The Open Group                  2003                      ISUNORDERED(3P)