ISNAN(3) BSD Programmer's Manual ISNAN(3)
isnan - test for not-a-number
#include <math.h> int isnan(real-floating x);
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.
It is determined whether the value of x is a NaN.
NaNs are not supported.
The isnan() macro returns a non-zero value if the value of x is a NaN. Otherwise 0 is returned.
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.
The isnan() macro conforms to ISO/IEC 9899:1999 ("ISO C99"). MirOS BSD #10-current March 5, 2004 1
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