signum
Determines the sign of the given double value. Returns -1.0 if the value is negative, 1.0 if the value is positive, and the value itself if it is either 0.0 or NaN.
Return
-1.0 if d is negative, 1.0 if d is positive, or d itself if it is 0.0 or NaN
Parameters
d
the double value whose sign is to be determined