各位大神好！我在學習的一個線代基礎課中，需要用到Python來計算向量，其中有一段代碼是這樣的from?math?import?sqrt,?acos,?pi?#導入sqrt,?acos,?pi from?decimal?import?Decimal,?getcontext getcontext().prec?=?30 class?Vector(): CANNOT_NORMALIZE_ZERO_VECTOR_MSG?=?'Cannot?normalize?the?zero?vector' def?__init__(self,?coordinates):? ????try: ????????if?not?coordinates: ????????????raise?ValueError ????????self.coordinates?=?tuple([Decimal(x)?for?x?in?coordinates])? ????????self.dimension?=?len(self.coordinates)? ????except?ValueError: ????????raise?ValueError('The?coordinates?must?be?nonempty') ????except?TypeError: ????????raise?TypeError('The?coordinates?must?be?an?iterable')? def?plus(self,?v):??#?向量加法 ????????new_coordinates?=?[x?+?y?for?x,?y?in?zip(self.coordinates,?v.coordinates)] ????????return?Vector(new_coordinates) def?dot(self,?v):?#?計算向量點積 ????return?sum([x?*?y?for?x,?y?in?zip(self.coordinates,?v.coordinates)]) def?angle_with(self,?v,?in_degrees?=?False):?#?計算向量夾角 ????try: ????????u1?=?self.normalized() ????????u2?=?v.normalized() ????????angle_in_radians?=?acos(u1.dot(u2)) ????????if?in_degrees: ????????????degrees_per_radian?=?180.?/?pi ????????????return?angle_in_radians?*?degrees_per_radian ????????else: ????????????return?angle_in_radians ????except?Exception?as?e: ????????if?str(e)?==?self.CANNOT_NORMALIZE_ZERO_VECTOR_MSG: ????????????raise?Exception('Cannot?compute?an?angle?with?the?zero?vector') ????????else: ????????????raise?e print('\n向量加法') v?=?Vector([8.218,?-9.341]) w?=?Vector([-1.129,?2.111]) print(v.plus(w)) print('\n計算向量夾角') v?=?Vector(['3.183',?'-7.627']) w?=?Vector(['-2.668',?'5.319']) print(v.angle_with(w)) v?=?Vector(['7.35',?'0.221',?'5.188']) w?=?Vector(['2.751',?'8.259',?'3.985']) print(v.angle_with(w,?in_degrees=True))在向量加法的代碼中，這個self.coordinates是v = Vector([8.218, -9.341])傳入的值，v.coordinates是w = Vector([-1.129, 2.111])傳入的值，我有個問題就是，為什么v后面要加上coordinates呢？這個v是類似self那樣作為引用，用于訪問這個屬性coordinates嗎？為什么不可以直接使用v呢？另外在“計算夾角向量”的代碼中，angle_in_radians = acos(u1.dot(u2))中的(u1.dot(u2))該怎么理解好呢？請大神賜教，謝謝！