Classifies its argument value as NaN, infinite, normal, subnormal or zero.
int fpclassify(real-floating x); (C99)
If the value of the argument is NaN, FP_NAN is returned.
If the value of the argument is infinite, FP_INFINITE is returned.
If the value of the argument is a normal number, FP_NORMAL is returned.
If the value of the argument is a subnormal number, FP_SUBNORMAL is returned.
If the value of the argument is 0, FP_ZERO is returned.
For the value returned by each macro, refer to math.h.
This macro classifies its argument value as NaN, infinite, normal, subnormal or zero.
If a type other than the floating-point type is passed to the argument, correct operation is not guaranteed.