ISNAN(3P)                                           POSIX Programmer's Manual                                          ISNAN(3P)



PROLOG
       This  manual  page is part of the POSIX Programmer's Manual.  The Linux implementation of this interface may differ (con-
       sult the corresponding Linux manual page for details of Linux behavior), or the  interface  may  not  be  implemented  on
       Linux.

NAME
       isnan - test for a NaN

SYNOPSIS
       #include <math.h>

       int isnan(real-floating x);


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

RETURN VALUE
       The isnan() macro shall return a non-zero value if and only if its argument has a NaN value.

ERRORS
       No errors are defined.

       The following sections are informative.

EXAMPLES
       None.

APPLICATION USAGE
       None.

RATIONALE
       None.

FUTURE DIRECTIONS
       None.

SEE ALSO
       fpclassify(), isfinite(), isinf(), isnormal(), signbit(), the Base Definitions volume of IEEE Std 1003.1-2001, <math.h>

COPYRIGHT
       Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1, 2003  Edition,  Standard  for
       Information  Technology -- Portable Operating System Interface (POSIX), The Open Group Base Specifications Issue 6, Copy-
       right (C) 2001-2003 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.open-
       group.org/unix/online.html .



IEEE/The Open Group                                           2003                                                     ISNAN(3P)