1ISUNORDERED(3P)            POSIX Programmer's Manual           ISUNORDERED(3P)
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PROLOG

6       This  manual  page is part of the POSIX Programmer's Manual.  The Linux
7       implementation of this interface may differ (consult the  corresponding
8       Linux  manual page for details of Linux behavior), or the interface may
9       not be implemented on Linux.
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NAME

12       isunordered - test if arguments are unordered
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SYNOPSIS

15       #include <math.h>
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17       int isunordered(real-floating x, real-floating y);
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DESCRIPTION

21       The isunordered() macro  shall  determine  whether  its  arguments  are
22       unordered.
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RETURN VALUE

25       Upon  successful  completion, the isunordered() macro shall return 1 if
26       its arguments are unordered, and 0 otherwise.
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28       If x or y is NaN, 0 shall be returned.
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ERRORS

31       No errors are defined.
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33       The following sections are informative.
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EXAMPLES

36       None.
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APPLICATION USAGE

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

52       None.
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FUTURE DIRECTIONS

55       None.
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SEE ALSO

58       isgreater(),   isgreaterequal(),   isless(),   islessequal(),   isless‐
59       greater(),   the   Base  Definitions  volume  of  IEEE Std 1003.1-2001,
60       <math.h>
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63       Portions of this text are reprinted and reproduced in  electronic  form
64       from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology
65       -- Portable Operating System Interface (POSIX),  The  Open  Group  Base
66       Specifications  Issue  6,  Copyright  (C) 2001-2003 by the Institute of
67       Electrical and Electronics Engineers, Inc and The Open  Group.  In  the
68       event of any discrepancy between this version and the original IEEE and
69       The Open Group Standard, the original IEEE and The Open Group  Standard
70       is  the  referee document. The original Standard can be obtained online
71       at http://www.opengroup.org/unix/online.html .
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75IEEE/The Open Group                  2003                      ISUNORDERED(3P)
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