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I want to know how to multiply array elements one by one.

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용준 권
용준 권 2022-3-15
评论： 용준 권 2022-3-15
Hello, I have some problems with making matlab code.
If I have 2x2 matrix. I want to calculate (1,1)x(1,1), (1,1)x(1,2) (1,1)x(2,1), (1,1)x(2,2)
(1,2)x(1,2), (1,2)x(2,1), (1,2)x(2,2) -> (1,2)x(1,1) is already exists in the first row.
(2,1)x(2,1), (2,1)x(2,2) -> (2,1)x(1,1), (2,1)x(1,2) are already existed in the previous rows.
(2,2) values.
(1,1) is the element of matrix value. for example) if matrix [1,2,3;4,5,6;7,8,9], then (1,1) means 1.
So, what I want to say is (1,1)x(1,2) = 1x2=2.
I want to expand this to m x m matrix.
how I make the code or which function should I use?
Until now I have used just ' for '.
I made the code with 4 parameter (ex) i,j,k,l)
However, this operation has duplicate values, and as the matrix becomes large, the operation speed becomes significantly longer.
plz help me....
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용준 권
용준 권 2022-3-15
1st column is for the distance between two matrix elements.
2nd column is for the product of two elements.
if I calculate (1,2)x(2,2), then the distance is the sqrt((2-1)^2+(2-2)^2).
the second column is the calculated value. That means if I calculate (1,2)x(2,2), then the value is 12.

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回答（1 个）

Arif Hoq
Arif Hoq 2022-3-15
Ran in:
A=[1 2; 3 4];
B1=A(1,1)*A(:);
B2=A(1,2)*A(:);
B3=A(2,1)*A(:);
B4=A(2,2)*A(:);
matrix=[B1 B2 B3 B4];
out=reshape(matrix,1,[]);
out2=unique(out)
out2 = 1×9
1 2 3 4 6 8 9 12 16
And I will save this result to the n x 2 matrix. In the above case, n=10.
no, its 9 element row vector. so you can not reshaped into n X 2 arrray.
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용준 권
용준 권 2022-3-15
B2's A(1,2)*A(2,1) and B3's A(2,1)*A(1,2) are duplicate values. I don't need this operation.
But, A(1,1)xA(2,2) = 1x4=4, A(1,2)xA(1,2) = 2x2 = 4 is different from the above.
The redundancy of the multiplication is unnecessary, but the redundancy of the result is important.
용준 권
용준 권 2022-3-15
So, what i want to say is I want to avoid redundancy in multiplication.

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