- x1 should be indexed with i1 and x0 with i0
- you first need to update j before you can use it as an index into x2
- the condition states that you should enter if i2 is not equal to i1
- i'm guessing that the matrix A you provided does not have the correct dimensions, i assume it should be a 7x7 matrix?
- also min( median( ) ) is not the same as the low median, since x2 is a vector the median will return a scalar

# Write matlab code for the following algorithm

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I have this algorithm

I write this code for my example

A = [10 -10; 1 0; -1 0; 0 -1 ; 0 1; 11 -10; -1 -1];

C = cov(A).^(-1/2).*A;

M = size(A,1);

omega = C*C';

x0=[];x1=[];x2=[];PS=[];

for i0=1:M

for i1=1:M

for i2=1:M

j = 0;

if isequal(i2,i1)

x2(j) = abs(omega(i1,i0)+omega(i2,i0));

j = j+1;

end

end

x1(j) = min(median(x2,'all')); % lower median

end

x0(j) = 1.1 .* min(median(x1,'all')); % lower median

end

for i3=1:M

PS(i3) = max(omega(i3)/x0);

end

but the above-mentioned code has many problems. I do not know how to fix it.

the result should be

PS = [16.77;0.839;0.839;0.839;0.839;17.609;1.677];

##### 0 Comments

### Accepted Answer

Karim
on 11 Aug 2022

Edited: Karim
on 11 Aug 2022

I'm not familiar with the algoritm, so it could still have some mistakes left...

However, i was able to identify a couple of mistakes:

Below i used an random A matrix, hence the 'PS' result is not the same as the one you expect. Where did you obtain the matrix A and the expected result?

A = [10 -10; 1 0; -1 0; 0 -1 ; 0 1; 11 -10; -1 -1];

% use a random A matrix...

A = rand(7) * 100;

C = cov(A)^(-1/2) * A;

M = size(A,1);

omega = C*C';

x0 = zeros(M ,1);

x1 = zeros(M ,1);

x2 = zeros(M-1,1); % 1 element less since we neglect the case where i2 == i1

PS = zeros(M ,1);

for i0 = 1:M

for i1 = 1:M

j = 0;

for i2 = 1:M

if i2 ~= i1

j = j + 1;

x2( j ) = abs( omega(i1,i0) + omega(i2,i0) );

end

end

x1( i1 ) = median(x2,'all');

end

x0( i0 ) = 1.1 * median(x1,'all');

end

for i3 = 1:M

PS(i3) = max( omega(i3)/x0 );

end

PS

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