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ISNAN(3)                 BSD 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").

BSD                              March 5, 2004                             BSD
NAME | LIBRARY | SYNOPSIS | DESCRIPTION | RETURN VALUES | SEE ALSO | STANDARDS