python matrix multiplication

1# input two matrices of size n x m 
2matrix1 = [[12,7,3], 
3        [4 ,5,6], 
4        [7 ,8,9]] 
5matrix2 = [[5,8,1], 
6        [6,7,3], 
7        [4,5,9]] 
8  
9res = [[0 for x in range(3)] for y in range(3)]  
10  
11# explicit for loops 
12for i in range(len(matrix1)): 
13    for j in range(len(matrix2[0])): 
14        for k in range(len(matrix2)): 
15  
16            # resulted matrix 
17            res[i][j] += matrix1[i][k] * matrix2[k][j] 
18  
19print (res) 
20

1>>> a = np.array([[ 5, 1 ,3], 
2                  [ 1, 1 ,1], 
3                  [ 1, 2 ,1]])
4>>> b = np.array([1, 2, 3])
5>>> print a.dot(b)
6array([16, 6, 8])