MATLAB: How to fix the “Subscript indices must either be real positive integers or logicals.” I am getting the errors the j(k) and l(k). the program works when I change the range but i only get ending term, any point in the right direction would be helpfu

subscript indices

z(1) = 1.5;
for k = 1:6
    fprintf('%d                 %5.8f                  %5.8f                             %5.8f\n',n , z(k), e(k), p(k));
  z(k+1) = (.5)*z(k) + sqrt(2)/2*z(k);
  x(k) = z(k+1);
  e(k) = z(k+1) - sqrt(2);
  j(k)= log((e(k))/log(e(k-1)));
  l(k)= log(e(k-1))/log(e(k-2));
  p(k) = j(k)/l(k);
end

Best Answer

Hi Janvier Solaris,
the main problem despite of posting non-executable code is the reference to e(k-2) for l(k) calculation. Since indices have to a positive integers or logicals it will not work for k <= 2. That code snippet does:
 z(1) = 1.5;
 for k = 1:6
    z(k+1) = (.5)*z(k) + sqrt(2)/2*z(k);
    x(k) = z(k+1);
    e(k) = z(k+1) - sqrt(2);
    if k > 2
       j(k)= log((e(k))/log(e(k-1)));
       l(k)= log(e(k-1))/log(e(k-2));
       p(k) = j(k)/l(k);
       fprintf('%d                 %5.8f                  %5.8f                             %5.8f\n',k , z(k), e(k), p(k));
    end
 end
Kind regards,
Robert
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