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

20       The functionality described on this reference page is aligned with  the
21       ISO C  standard.  Any  conflict between the requirements described here
22       and the ISO C standard is unintentional. This  volume  of  POSIX.1‐2017
23       defers to the ISO C standard.
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25       The  isunordered()  macro  shall  determine  whether  its arguments are
26       unordered.
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RETURN VALUE

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

35       No errors are defined.
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37       The following sections are informative.
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EXAMPLES

40       None.
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APPLICATION USAGE

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

56       None.
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FUTURE DIRECTIONS

59       None.
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SEE ALSO

62       isgreater(), isgreaterequal(), isless(), islessequal(), islessgreater()
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64       The Base Definitions volume of POSIX.1‐2017, <math.h>
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67       Portions  of  this text are reprinted and reproduced in electronic form
68       from IEEE Std 1003.1-2017, Standard for Information Technology --  Por‐
69       table  Operating System Interface (POSIX), The Open Group Base Specifi‐
70       cations Issue 7, 2018 Edition, Copyright (C) 2018 by the  Institute  of
71       Electrical  and  Electronics Engineers, Inc and The Open Group.  In the
72       event of any discrepancy between this version and the original IEEE and
73       The  Open Group Standard, the original IEEE and The Open Group Standard
74       is the referee document. The original Standard can be  obtained  online
75       at http://www.opengroup.org/unix/online.html .
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77       Any  typographical  or  formatting  errors that appear in this page are
78       most likely to have been introduced during the conversion of the source
79       files  to  man page format. To report such errors, see https://www.ker‐
80       nel.org/doc/man-pages/reporting_bugs.html .
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84IEEE/The Open Group                  2017                      ISUNORDERED(3P)
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