一位向量a(n,)减去一位向量b(n,) 与 减去 c(n,1)的结果不同!
a = np.array([1,2,3,4])
b = np.ones(4)
c = b.reshape(-1,1)
print(a-b)
#[0. 1. 2. 3.]
print(a-c)
"""
[[0. 1. 2. 3.]
[0. 1. 2. 3.]
[0. 1. 2. 3.]
[0. 1. 2. 3.]]
"""
print(np.sum((a-b) ** 2))
#14.0
print(np.sum((a-c) ** 2))
#56.0