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I have 2 matrices with size (4,4) and (4,5) respectively. I want the element (2,1) in the second matrix to try all values in the first column in the first matrix and at each value, produce new matrix

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Mahmoud Ahmed
Mahmoud Ahmed 2017-5-8
关闭： MATLAB Answer Bot 2021-8-20
I have 2 matrices with size (4,4) and (4,5) respectively. I want the element located at (2,1) in the second matrix to take all the values in the first column in the first matrix. How can I do this?
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Mahmoud Ahmed
Mahmoud Ahmed 2017-5-8
编辑：Mahmoud Ahmed 2017-5-8
A = [1:4 ; 5:8 ; 9:12 ; 13:16] B = zeros(4,5) B(2,1) = 0 now. I want B(2,1) to try all the values from the 1st column in A matrix B(2,1) = A(:,1) B(2,1) equals at the 1st time 1 at 2nd time 4 at 3rd time 9 at 4th time 13 and at each time I want to see the new B matrix

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KSSV
KSSV 2017-5-8
A = [1:4 ; 5:8 ; 9:12 ; 13:16] ;
B = zeros(4,5) ;
for i = 1:4
B(:,i) = A(:,i)
end
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Mahmoud Ahmed
Mahmoud Ahmed 2017-5-8
with this code, the output is B =
1 0 0 0 0
5 0 0 0 0
9 0 0 0 0
13 0 0 0 0
and I want B(2,1) only to be assigned with each value from the 1st column of A at different times
Guillaume
Guillaume 2017-5-8
Probably the easiest is to replicate your B in the 3rd dimension and copy the column of A along that dimension.
A = [1:4 ; 5:8 ; 9:12 ; 13:16]
B = rand(4, 5);
newB = repmat(B, [1, 1, size(A, 1)]); %replicate B in the 3rd dimensions as many times as there are rows in A
newB(2, 1, :) = A(:, 1); %and copy 1st column of A, overwrite whatever was in B(2, 1)
You can then iterate over the pages (3rd dimension) of that newB to do whatever it is you want to do.
for page = 1 :size(newB, 3)
%do something with B(:, :, page)
end

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