code: def new_get_angle_diff(v1,v2):
      
      v1 = numpy.array(v1)
      v2 = numpy.array(v2)
      angle = numpy.arctan2(numpy.linalg.norm(numpy.cross(v1, v2)), numpy.dot(v1, v2))
      return math.degrees(angle)
docs: returns angular difference in degrees between two vectors.  may be more precise in certain cases.  see SPD