没有 Numpy 的广义矩阵乘法

Question

I want to make a system that allows me to input 2 matrixes, and it output a correct answer. I've gotten it to work with specifically a 1 x 3 * 3 x 2. But I want to make it more open ended. How could I do this?

# 1 x 3 by 3 x 2
def matmul(matA, matB):

    p1 = matA[0][0] * matB[0][0]
    p2 = matA[1][0] * matB[2][0]
    p3 = matA[2][0] * matB[4][0]
    
    num1 = p1 + p2 + p3
    
    p1 = matA[0][0] * matB[1][0]
    p2 = matA[1][0] * matB[3][0]
    p3 = matA[2][0] * matB[5][0]
    
    num2 = p1 + p2 + p3

    # Output is a 1 x 2 Matrix
    result = [num1, num2]
    print(result)

# ----------------------------------- #

# 1 x 3 Matrix
A = (
 [5],
 [-5],
 [10]
)

# 3 x 2 Matrix
B = (
 [-10], [13],
 [57], [-37],
 [-96], [15]
)

# Outputs a 1 x 2 Matrix
MatMult(A, B)

Answer 1

I expect that you will find many example of this, but here is working code. In particular, you will use nested for loops or nested list comprehension to generate the final matrix.

# Program to multiply two matrices using nested loops

# 3x3 matrix
X = [[12,7,3],
    [4 ,5,6],
    [7 ,8,9]]
# 3x4 matrix
Y = [[5,8,1,2],
    [6,7,3,0],
    [4,5,9,1]]
# result is 3x4
result = [[0,0,0,0],
         [0,0,0,0],
         [0,0,0,0]]

# iterate through rows of X
for i in range(len(X)):
   # iterate through columns of Y
   for j in range(len(Y[0])):
       # iterate through rows of Y
       for k in range(len(Y)):
           result[i][j] += X[i][k] * Y[k][j]

for r in result:
   print(r)

And here is an example of the same: https://www.programiz.com/python-programming/examples/multiply-matrix

Answer 2

# 1 x 3 Matrix
A = [ [5, -5, 10]]

# 3 x 2 Matrix
B = [
 [-10, 13],
 [57, -37],
 [-96, 15]
]

def mult_matx(A, B):
    
    rowsA = len(A)
    colsB = len(B[0])
    result = [[0] * colsB for i in range(rowsA)]
    
    for i in range(rowsA):
        
        # iterating by column by B
        for j in range(colsB):
            
            
            # iterating by rows of B
            for k in range(len(B)):
                
                result[i][j] += A[i][k] * B[k][j]
 
    for r in result:
        print(r)