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ISNAN(3)                   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.

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").

CAVEATS
     On VAX the isnan() function always returns 0, as the architecture doesn't
     support NaN.

NetBSD 10.99                  September 27, 2017                  NetBSD 10.99