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

13       isunordered — test if arguments are unordered
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SYNOPSIS

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

21       The functionality described on this reference page is aligned with  the
22       ISO C  standard.  Any  conflict between the requirements described here
23       and the ISO C standard is unintentional. This  volume  of  POSIX.1‐2008
24       defers to the ISO C standard.
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26       The  isunordered()  macro  shall  determine  whether  its arguments are
27       unordered.
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RETURN VALUE

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

36       No errors are defined.
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38       The following sections are informative.
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EXAMPLES

41       None.
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APPLICATION USAGE

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

57       None.
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FUTURE DIRECTIONS

60       None.
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SEE ALSO

63       isgreater(), isgreaterequal(), isless(), islessequal(), islessgreater()
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65       The Base Definitions volume of POSIX.1‐2008, <math.h>
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68       Portions  of  this text are reprinted and reproduced in electronic form
69       from IEEE Std 1003.1, 2013 Edition, Standard for Information Technology
70       --  Portable  Operating  System  Interface (POSIX), The Open Group Base
71       Specifications Issue 7, Copyright (C) 2013 by the Institute of Electri‐
72       cal  and  Electronics  Engineers,  Inc  and  The  Open Group.  (This is
73       POSIX.1-2008 with the 2013 Technical Corrigendum  1  applied.)  In  the
74       event of any discrepancy between this version and the original IEEE and
75       The Open Group Standard, the original IEEE and The Open Group  Standard
76       is  the  referee document. The original Standard can be obtained online
77       at http://www.unix.org/online.html .
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79       Any typographical or formatting errors that appear  in  this  page  are
80       most likely to have been introduced during the conversion of the source
81       files to man page format. To report such errors,  see  https://www.ker‐
82       nel.org/doc/man-pages/reporting_bugs.html .
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86IEEE/The Open Group                  2013                      ISUNORDERED(3P)
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