python矩阵乘法

# 矩阵乘法
import numpy as np


# x,y是向量
def naive_vector_dot(x, y):
    sum = 0
    for i in range(x.shape[0]):
        sum += x[i] * y[i]
    return sum

# a,b是矩阵
def vector_dot(a, b):
    z = np.zeros((a.shape[0], b.shape[1]))
    for i in range(a.shape[0]):
        for j in range(b.shape[1]):
            z[i, j] = naive_vector_dot(a[i, :], b[:, j])
    return z

#a : <class 'numpy.ndarray'>
a = np.arange(1, 5).reshape(2, 2)
b = np.arange(6, 10).reshape(2, 2)
c = np.dot(a, b)
c_ = vector_dot(a, b)
print(c)
print(c_)
print(c == c_)