Python 矩陣乘法

def matrixMul(A, B):    res = [[0] * len(B[0]) for i in range(len(A))]    for i in range(len(A)):        for j in range(len(B[0])):            for k in range(len(B)):                res[i][j] += A[i][k] * B[k][j]    return resdef matrixMul2(A, B):    return [[sum(a * b for a, b in zip(a, b)) for b in zip(*B)] for a in A]a = [[1,2], [3,4], [5,6], [7,8]]b = [[1,2,3,4], [5,6,7,8]]
print matrixMul(a,b)print matrixMul(b,a)print "-"*90
print matrixMul2(a,b)print matrixMul2(b,a)print "-"*90
from numpy import dotprint map(list,dot(a,b))print map(list,dot(b,a))
#Out:#[[11, 14, 17, 20], [23, 30, 37, 44], [35, 46, 57, 68], [47, 62, 77, 92]]#[[50, 60], [114, 140]]#------------------------------------------------------------------------------------------#[[11, 14, 17, 20], [23, 30, 37, 44], [35, 46, 57, 68], [47, 62, 77, 92]]#[[50, 60], [114, 140]]#------------------------------------------------------------------------------------------#[[11, 14, 17, 20], [23, 30, 37, 44], [35, 46, 57, 68], [47, 62, 77, 92]]#[[50, 60], [114, 140]]