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 res
def 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 = [[1,2,3,6,7,8]]
print matrixMul(a,b)
print matrixMul(b,a)
print "-"*90
print matrixMul2(a,b)
print matrixMul2(b,a)
print "-"*90
from numpy import dot
print 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]]
#------------------------------------------------------------------------
#[[11,140]]