Write a program so that with help of 3 for-end loops we form a matrix C that will be equivalent to C= AB - BA

Question

Iva Budan 2022-4-29

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评论： Jan 2022-5-2

Let 2 matrices (A and B) be given in MatLab.Write a program so that with help of 3 for-end loops we form a matrix C that will be equivalent to C= A*B - B*A

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Bruno Luong 2022-4-29

@Jakub Devera matrix is 2D, and naive multipling two matrices requires 3 nested loops.

Jan 2022-4-29

编辑：Jan 2022-4-29

This is a homework question. As usual, post, what you have tried so far and ask a specific question concern the remaining Matlab problem.

The actual problem is interesting. You can avoid to calculate A*B and B*A explicitly.

@Jakub Devera: If A*B and B*A is mathematically defined, A and B must be square matrices.

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Answer 1

Srija Kethiri 2022-5-2

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在 MATLAB Online 中打开

Hi Iva,

From my understanding you want to to get a matrix C, where C = A*B - B*A. To get the matrix C it is possible only if A and B both are square matrices with same dimension.

The code for finding C is:

[c,d] = size(A); 
[e,f] = size(B); 
C = zeros(c,c); 
if(c==d && e==f && c==e)    
    for i=1:c 
        for j=1:c 
           sum1 =0; 
           sum2 =0; 
            for p = 1:c 
            sum1 = sum1 + A(i,p)*B(p,j); 
            sum2 = sum2 +B(i,p)*A(p,j);     
            C(i,j)  = sum1-sum2; 
            end 
        end 
    end 
end 

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John D'Errico 2022-5-2

Please don't answer obvious homework assignment questions, when no effort was made or shown. This does not help the student. It only teaches them to post the rest of their homework on Answers, and that hurts the site.

Jan 2022-5-2

I agree with John.

Your code overwrites C(i,j) in each iteration of the inner loop. One variable would be enough for the accumulation.

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Answer 2

Matt J 2022-5-2

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编辑：Matt J 2022-5-2

在 MATLAB Online 中打开

A=rand(4); B=rand(4); %synthetic input data
M={A,B;B,A};
mask=[1 1;1,-1];
for i=1:4
 M{i}=mask(i)*M{i};
end
for i=1:2
 M{i,1}=M{i,1}*M{i,2};
end
C=0;
for i=1:2
 C=C+M{i};
end
C-(A*B-B*A)%Check the result
ans = 4×4
     0     0     0     0
     0     0     0     0
     0     0     0     0
     0     0     0     0