# Elements of Array Should not be the Same

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Gözde Üstün on 25 Jun 2020
Commented: Gözde Üstün on 28 Jun 2020
Hello,
I have this value for element of my list: And I have this code:
function [A,B] = CHSHmeasurement(d)
A=zeros(d,d,2,d);
B=A;
projectors_of_sigma_x = [1/sqrt(2)*[1;1],1/sqrt(2)*[1;-1]];
for k = 1:d
for l =1:length(projectors_of_sigma_x)
%A(k,k,1,k)=projectors_of_sigma_x(l);
A(:,:,1,k)=projectors_of_sigma_x(l);
end
end
end
However I have the same element for A although I have the different elements in the projectors_of_sigma_x  madhan ravi on 25 Jun 2020
Please provide the full error message. And d?
Gözde Üstün on 25 Jun 2020
There is no error message but as you can see I have different value for projectors_of_sigma_x = [1/sqrt(2)*[1;1],1/sqrt(2)*[1;-1]]; (v1 and v2 you can see from the images clearly) but for the A(:,:1,1) and A(:,:,1,2) I have the same matrix and d is = 2

madhan ravi on 25 Jun 2020
Edited: madhan ravi on 25 Jun 2020
for k = 1:d
for l =1:d
A(:,:,1,k) = repmat(projectors_of_sigma_x(:,k), 1, d);
end
end
I suggest you to read https://www.mathworks.com/company/newsletters/articles/matrix-indexing-in-matlab.html , first deal with 2D matrices before dealing with higher dimension matrices.

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Gözde Üstün on 27 Jun 2020
Then we dont need to second for loop right?? or should I change k as l in this line repmat(projectors_of_sigma_x(:,k), 1, d); ?? @madhan ravi
I have a problem for d>2 (and d should be even) For d >2 the result should be block diagonal like that:
0.7071 0.7071 0 0
0.7071 0.7071 0 0
0 0 0.7071 0.7071
0 0 0.7071 0.7071
And I tried almost all combinations with blkdiag but I can't cope with it
for k = 1:d
for l =1:d
A(:,:,1,k) = repmat(projectors_of_sigma_x(:,k), 1, d);
if k > 2
A(:,:,1,k) = repmat({A(:,:,1,k)}, 1, d/2); %This line and the following line I am trying to create a matrix which is a blog diagonal of the previous result for even d and of course d>2
A(:,:,1,k) = blkdiag(A{:,:,1,k});
end
end
end
madhan ravi on 28 Jun 2020
When do you need ? I don't have time to analyse that sorry :( . I see that you have asked the same question already!
Gözde Üstün on 28 Jun 2020
Ahh no worries! I can wait (till the tuesday) Yeah I asked and each question includes different version of my combination because I have tried too many combiations

R2020a

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