MATLAB: HELP : Subscript indices must either be real positive integers or logicals – AGAIN

indexingintegerlogical?MATLAB

I need your help to solve the problem of subscript index that must either be positive integer or logical. Can any one help to correct this ?
A = magic(5);
  M1 = size(A,1);
  M2 = size(A,2);
  E = [5 8 20];
  for x = 1:M1
    for y = 1:M2
    if A(A(x,y) == E)
        A(x-1,y) = 5
      end
    end
    end
Thank you!

Best Answer

By including 'again' in the title I hope that you are learning from previous solutions and that this is a different type of cause to your previous such problems.
The line
A(x-1,y) = 5
fails first time round the loop because x is 1 so x-1 is 0 which is not a valid array index (this is what the error message tells you - it must be a real positive integer or a logical - 0 is neither of those).
How to fix it depends on your intent. Starting your for loop indexed from 2 instead of 1 would remove the error but may not be the solution you want.
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