Matrices in a matrix
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I have this matrix in which there are 9 different matrices each one is composed by 6 * 6 elements
![](https://www.mathworks.com/matlabcentral/answers/uploaded_files/164111/image.png)
I want pre and post multiply each matrix-elements in this way:
![](https://www.mathworks.com/matlabcentral/answers/uploaded_files/164113/image.png)
A is a matrix with the same size of R
P.S. : I have store R and A as a sparse matrices
How can I do?
Thanks
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Accepted Answer
David Goodmanson
on 15 May 2017
Edited: David Goodmanson
on 15 May 2017
Hi UGO, should your top row read R11, R12, R13? at any rate, try
z = zeros(size(A));
C = [A z z;z A z;z z A];
B = C.'*R*C
where C is a block diagonal matrix.
More Answers (1)
John
on 15 May 2017
try
% if A is 6x6
A = rand(6);
A = repmat(A,3);
% if R is 18x18, constructed from multiple 6x6 sub Rij matrices
B = A'*R*A
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