计算三维空间某点距离原点的欧式距离o-dis(a,b)

a,b表示两个坐标点，分别为(x1,y1,z1)和(x2,y2'z2)

def distance(a, b):
    return ((a[0]-b[0])**2+(a[1]-b[1])**2+(a[2]-b[2])**2)**0.5

a = (1,2,3)
b = (4,5,6)
print(distance(a,b))