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 functionality described on this reference page is aligned with the ISO C standard. Any
       conflict between the requirements described here and the ISO C standard is  unintentional.
       This volume of POSIX.1‐2017 defers to the ISO C standard.

       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, 1 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 POSIX.1‐2017, <math.h>

COPYRIGHT

       Portions of this text are reprinted and  reproduced  in  electronic  form  from  IEEE  Std
       1003.1-2017,  Standard  for  Information Technology -- Portable Operating System Interface
       (POSIX), The Open Group Base Specifications Issue 7, 2018 Edition, Copyright (C)  2018  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 .

       Any typographical or formatting errors that appear in this page are most  likely  to  have
       been  introduced  during  the conversion of the source files to man page format. To report
       such errors, see https://www.kernel.org/doc/man-pages/reporting_bugs.html .