How do I sum specific values of one matrix to another one?
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If I have a square matrix A, how can I add specific values from another matrix B
A=zeros(3)
B=[1 2;3 4]
If I want to sum such us B(1,1) in A(2,2) and B(2,2) in A(3,3) how can I do it so I can get:
A=[0 0 0;
0 2 0;
0 0 4]
I've tried using indexing but it turns out to be annoying for a square matrix of 10x10
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Image Analyst
2021년 11월 16일
편집: Image Analyst
2021년 11월 16일
A=zeros(3);
B=[1 2;3 4];
A(2,2) = B(1,2);
A(3,3) = B(2,2)
Not sure what you want to sum with a 10x10 A and/or B. Please explain with a matrix of that size.
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Image Analyst
2021년 11월 16일
편집: Image Analyst
2021년 11월 16일
What exactly do you mean by "sum" and "to" in "sum specific values of one matrix to another one"? Do you mean you want to add column 2 of B to A at positions where B is shifted one row and column into A. So if A is N rows and B is (N-1) rows then you'd add the values of column 2 of B to the diagonal of A, like this:
rows = 3;
A = zeros(rows); % Any rows-by-rows square array - could be any values.
B = reshape(1:(rows-1)^2, rows-1, rows-1)' % E.g. [1 2;3 4]
% Add column 2 of B, at one row more diagonally, to A.
for row = 2 : rows
A(row, row) = A(row, row) + B(row - 1, 2);
end
A % Show the final A in command window.
Essentially this is a for loop version of Star's vectorized version.
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