1ISNAN(3P)                  POSIX Programmer's Manual                 ISNAN(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       isnan — test for a NaN
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SYNOPSIS

16       #include <math.h>
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18       int isnan(real-floating x);
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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  isnan() macro shall determine whether its argument value is a NaN.
27       First, an argument represented in a format wider than its semantic type
28       is  converted  to its semantic type. Then determination is based on the
29       type of the argument.
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RETURN VALUE

32       The isnan() macro shall return a non-zero value  if  and  only  if  its
33       argument has a NaN value.
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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       None.
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RATIONALE

47       None.
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FUTURE DIRECTIONS

50       None.
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SEE ALSO

53       fpclassify(), isfinite(), isinf(), isnormal(), signbit()
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55       The Base Definitions volume of POSIX.1‐2008, <math.h>
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58       Portions  of  this text are reprinted and reproduced in electronic form
59       from IEEE Std 1003.1, 2013 Edition, Standard for Information Technology
60       --  Portable  Operating  System  Interface (POSIX), The Open Group Base
61       Specifications Issue 7, Copyright (C) 2013 by the Institute of Electri‐
62       cal  and  Electronics  Engineers,  Inc  and  The  Open Group.  (This is
63       POSIX.1-2008 with the 2013 Technical Corrigendum  1  applied.)  In  the
64       event of any discrepancy between this version and the original IEEE and
65       The Open Group Standard, the original IEEE and The Open Group  Standard
66       is  the  referee document. The original Standard can be obtained online
67       at http://www.unix.org/online.html .
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69       Any typographical or formatting errors that appear  in  this  page  are
70       most likely to have been introduced during the conversion of the source
71       files to man page format. To report such errors,  see  https://www.ker‐
72       nel.org/doc/man-pages/reporting_bugs.html .
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76IEEE/The Open Group                  2013                            ISNAN(3P)
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