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

12       isnan - test for a NaN
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SYNOPSIS

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

21       The isnan() macro shall determine whether its argument value is a  NaN.
22       First, an argument represented in a format wider than its semantic type
23       is converted to its semantic type. Then determination is based  on  the
24       type of the argument.
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RETURN VALUE

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

42       None.
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FUTURE DIRECTIONS

45       None.
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SEE ALSO

48       fpclassify(), isfinite(), isinf(), isnormal(), signbit(), the Base Def‐
49       initions volume of IEEE Std 1003.1-2001, <math.h>
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52       Portions  of  this text are reprinted and reproduced in electronic form
53       from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology
54       --  Portable  Operating  System  Interface (POSIX), The Open Group Base
55       Specifications Issue 6, Copyright (C) 2001-2003  by  the  Institute  of
56       Electrical  and  Electronics  Engineers, Inc and The Open Group. In the
57       event of any discrepancy between this version and the original IEEE and
58       The  Open Group Standard, the original IEEE and The Open Group Standard
59       is the referee document. The original Standard can be  obtained  online
60       at http://www.opengroup.org/unix/online.html .
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64IEEE/The Open Group                  2003                            ISNAN(3P)
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