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.
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 9.2 September 27, 2017 NetBSD 9.2
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