isnan(3) - NetBSD Manual Pages

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ISNAN(3)                NetBSD Library Functions Manual               ISNAN(3)


NAME

     isnan -- test for not-a-number


LIBRARY

     Standard C Library (libc, -lc)


SYNOPSIS

     #include <math.h>

     int
     isnan(real-floating x);


DESCRIPTION

     The isnan() macro determines whether its argument x is not-a-number
     (``NaN'').  An argument represented in a format wider than its semantic
     type is converted to its semantic type first.  The determination is then
     based on the type of the argument.

   IEEE 754
     It is determined whether the value of x is a NaN.

   VAX
     NaNs are not supported.


RETURN VALUES

     The isnan() macro returns a non-zero value if the value of x is a NaN.
     Otherwise 0 is returned.


SEE ALSO

     fpclassify(3), isfinite(3), isinf(3), isinff(3), isnanf(3), isnormal(3),
     math(3), signbit(3)

     IEEE Standard for Binary Floating-Point Arithmetic, Std 754-1985, ANSI.


STANDARDS

     The isnan() macro conforms to ISO/IEC 9899:1999 (``ISO C99'').

NetBSD 6.0                       March 5, 2004                      NetBSD 6.0