Hi everyone! I need your help.

I have a 3D matrix, X which is 83x92x80. What I need to do is the following:

I tried

    % code
% 
for n=1:size(X, 3);
    for j=3:n;
          ss=sum((X (j-1)) .*( X (j-2)) ./ ((n-1) .* (n-2))) ./ 80;
    end
end

The result I expect is matrix.

Thank you Chane

[Image Analyst]

I'm not sure why you're using n as a loop iterator. I see nothing that says n should be a loop iterator. It looks like n should be a constant as far as I can see. It looks like the looping is only over the j variable, not n.

I also don't know what "x sub j" means. Is that the jth element of a vector x? Do you have multiple variables with different names, like x3, x4, x5, x6, ... xn?

And I don't know what the square brackets mean. Do they enclose indexes? Like xj[(j-1)*(j-2)] would be the row of xj that [(j-1)*(j-2)] evaluates to? Or are you taking the array xj (say x3 or x4 or whatever) and multiplying by the scalar [(j-1)*(j-2)] and dividing by the scalar [(n-1)*(n-2)]? It's tough to tell when you're not using standard MATLAB syntax.

So let's say j is 3 and n is 20. Is the sum x20 * [(3-1)*(3-2)] / [(20-1)*(20-2)], which equals x20 * [2*1] / [19*18] which equals x20 * 2/342?

Answer 1

[KALYAN ACHARJYA]

%There is no error, 
%X=input Matrix
for n=1:size(X, 3);
  for j=3:n;
        ss=sum((X (j-1)).*( X (j-2))./ ((n-1) .* (n-2)))./ 80;
  end
end

[Engdaw Chane]

KALYAN, Thank you. I want the result in a matrix. but here the result is just an element.