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Hi,

I have a cell array of 4*4 size, each cell has a vector of 10 elements.

{0×0 double} {10×1 double} {10×1 double} {10×1 double}

{0×0 double} {0×0 double} {10×1 double} {10×1 double}

{0×0 double} {0×0 double} {0×0 double} {10×1 double}

{0×0 double} {0×0 double} {0×0 double} {0×0 double}

I want to extract individual elements of the cell sequentially and form a matrix like in the following. How can I form the matrix, A_1? Can you help me?

A_1 is a matrix consist of first element of each cell (as follows)=

0 x1 x2 x3

0 0 y1 y2

0 0 0 z3

0 0 0 0 ]; then the 2nd element of of every cell will form another 4*4 matrix=A_2,

3rd element of every cell will form 4*4 matrix=A_3,.....and so on up to A_10. With these A_1, A_2,...,A_10 matrices, I want to add its transpose+ Identity matrix(i.e. eye(4)). Finally, it should be like this

FullMatrix(1) = A_1+A_1(transpose)+eye(4)=

1 x1 x2 x3

x1 1 y1 y2

x2 y1 1 z3

x3 y2 z3 1;

FullMatrix(2), FullMatrix(3),......,FullMatrix(10). I've tried but failed to do it. Your support is highly appriciate. Thanks & Regards, sa

DGM
on 13 May 2021

Edited: DGM
on 13 May 2021

This is what I did:

% build test array

a = [1 2 3 4].';

b = [2 3 4 5].';

c = [5 4 4 5].';

d = [7 3 4 5].';

e = [1 3 4 5].';

f = [9 7 6 5].';

CC = {0 a b c;

0 0 d e;

0 0 0 f;

0 0 0 0};

% these are the indices of triu for 4x4

idx = [5 9 10 13 14 15];

% make sure vectors share the same orientation

% this may or may not be necessary depending on how CC is made

CC = cellfun(@(x) x(:),CC,'UniformOutput',false);

% extract just the nonzero part of CC

C = [CC{idx}];

% build the outputs

A1 = zeros(4,4);

A1(idx) = C(1,:)

A2 = zeros(4,4);

A2(idx) = C(2,:)

% ... and so on

At that point, you can do whatever you want with A1, A2, etc.

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