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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
I want pre and post multiply each matrix-elements in this way:
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?


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Accepted Answer

David Goodmanson
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.

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UGO mela
UGO mela on 15 May 2017
It works perfectly!

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More Answers (1)

John on 15 May 2017
% 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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