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mxn and nxn matrix element-wise multiplication without for loop

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ebon T
ebon T on 26 Oct 2020 at 14:49
Commented: ebon T on 26 Oct 2020 at 16:45
I have 2 2D matrices. First one, A, is mxn where m=n*k and second one, B, is nxn. How do I do element-wise multiplication of every nxn square sub matrix of A with B without for loop? and sum all elements of every multiplied nxn matrix and get a nx1 vector? Below is what I did with for loop. I need to perform the for loop in one row.
n = 10;
k = 5;
A = rand(k*n,n);
B = rand(n,n);
results = zeros(k,1);
for i=1:k
results(i) = sum(B.*A(1+n*(i-1):i*n,:),'all');


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ebon T
ebon T on 26 Oct 2020 at 15:37
Actually as long as it creates the nx1 vector in one line it is fine.
Cris LaPierre
Cris LaPierre on 26 Oct 2020 at 15:41
What about the requirement to use elementwise multiplication and not use for loops? What about achieving this all in a single row?
ebon T
ebon T on 26 Oct 2020 at 15:48
If the solution can provide all of these then it is perfect! If it is not possible to vectorize then one line of solution also acceptable.

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