fpclassify - macro to classify floating-point numbers

Syntax	#include <math.h> C11 int fpclassify (x); (End)
Description	x must be an expression of type float, double oder long double. The macro returns a constant for classifying of x.
Return val.	FP_ZERO	x has the value 0
	FP_SUBNORMAL	x is an unnormalized floating-point number !=  0 (the leading heh-digit of x is 0)
	FP_NORMAL	x is a normalized floating-point number !=  0
	FP_INFINITE	the value of x is +/-Infinity
	FP_NAN	the value of x is +/-NaN
Notes	In this implementation only the values FP_ZERO, FP_SUBNORMAL and FP_NORMAL are returned.
See also	isfinite, isinf, isnan, isnormal, math.h.