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+1 vote
2 views
by (130 points)

I want to multiply these two matrices using pure python. Input (M1 is 3*3 and Mt is a 3*2)

M1 =  [[1.0016, 0.0, -16.0514],
       [0.0, 10000.0, -40000.0],
       [-16.0514, -40000.0, 160513.6437]]
Mt =  [(1.0, 1.0),
       (0.0, 0.25),
       (0.0, 0.0625)]

Mt is zip transpose of another matrix. My code is :

def mtxmultply (X, Y):
    Z = [[0 for row in range(len(X))] for col in range(len(Y[0]))]
    for i in range(len(A)):
        for j in range(len(Y[0])):
            for k in range(len(Y)):
                Z[i][j] += X[i][k]*Y[k][j]
    return Z

IndexError: list index out of range. Not getting the surety if Mt is recognised as an matrix & is still a list object. But technically this should work.

1 Answer

+2 votes
by (10.9k points)
edited by

The code should be like this for multiplication of two matrices in python-

# take a 3x3 matrix

C = [[1,1,1],

   [1,1,1], [1,1,1]]

 # take a 3x4 matrix     

D= [[2,2,2, 2],

   [2,2,2,2],

   [2,2,2,2]]

     R = [[0, 0, 0, 0],

       [0, 0, 0, 0],

       [0, 0, 0, 0]]

 # iterating by row of A

for i in range(len(C)):

  # iterating by column by D  

   for j in range(len(D[0])):

     # iterating by rows of D

       for k in range(len(D)):

           R[i][j] += C[i][k] * D[k][j]

 for s in result:

   print(s)

 output-

[[6,6,6,6],

[6,6,6,6],

[6,6,6,6]]

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