The sign of $(GAMMA)(x).
Returns -1 if $(GAMMA)(x) < 0, +1 if $(GAMMA)(x) > 0, NaN if sign is indeterminate.
See Implementation
The sign of $(GAMMA)(x).
Returns -1 if $(GAMMA)(x) < 0, +1 if $(GAMMA)(x) > 0, NaN if sign is indeterminate.