10-7.py 文件源码

def angle(self, n):
        # ?? n???? ???????????
        r = math.sqrt(sum(x * x for x in self[n:]))
        a = math.atan2(r, self[n - 1])
        if (n == len(self)) and (self[-1] < 0):
            return math.pi * 2 - a
        else:
            return a