两个数组 a 和 b 形状相同，即满足 a.shape == b.shape，那么 a*b 的结果就是 a 与 b 数组对应位相乘，相加，
当维度不同时，广播机制
import numpy as np
a = np.array([[0,1,2,3],
[1,1,2,3],
[2,1,2,3],
[3,1,2,3]])
b = np.array([0,1,2,3])
c = np.array([[0,1,2,3]])
print(a+ b)
print(a+c)
结果
[[0 2 4 6]
[1 2 4 6]
[2 2 4 6]
[3 2 4 6]]
[[0 2 4 6]
[1 2 4 6]
[2 2 4 6]
[3 2 4 6]]
