FP_NAN

From Cppreference

Defined in header `<cmath>`

#define FP_NAN /implementation defined/		(C++11 feature)

The FP_NAN macro expands to an integer constant expression. It represents a type of floating point values and indicates that the value is not-a-number (NaN).

[edit] See also

fpclassify (C++11)

categorizes the given floating point value
(function)

FP_INFINITE (C++11)

indicates infinite floating point value
(macro constant)

FP_NORMAL (C++11)

indicates normal number
(macro constant)

FP_SUBNORMAL (C++11)

indicates subnormal number
(macro constant)

FP_ZERO (C++11)

indicates zero
(macro constant)