python实现矩阵乘法的方法

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 "-"*90print matrixMul2(a,b)print matrixMul2(b,a)print "-"*90from 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]]