Fibonacci Sequence and Golden Ratio issue

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Mitul Dattani 2018-5-10

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https://ww2.mathworks.cn/matlabcentral/answers/400029-fibonacci-sequence-and-golden-ratio-issue

评论： Guillaume 2018-5-10

I was revising for an exam coming up and had to a fibonacci sequence and golden ratio

%delta = precision to 'm' sig figs
m = 3;
delta = 0.5*10^-m;
%Start from the calculation of n=2
n=2;
%only store two f numbers at a time
F1 = 1;
F2 = 2;
phi = F2/F1;
fprintf('At n = 2: F(n-1) = %d, F(n) = %d, phi = %.*f. \n',F1, F2, m, phi);
for n = 3:100
   Ftemp = F2;
   F2 = F1 + F2;
   F1 = Ftemp;
     phiold = phi;
     phi = F2/F1;
     fprintf('At n = %d: F(n-1) = %d, F(n) = %d, phi = %.*f.\n',n,F1,F2,m,phi);
      if abs(phiold-phi) < delta
          phi = round(phi,m);
          fprintf('Phi = %.*f is now precide to %d d.p. \n',m,phi,m);
          break
      end
  end

with the above code if I use F = ones(1,2) instead of declaring F1 and F2 as 1 and 1, I get 12 iterations where declaring f1 and f2 as i did in the code above I get 11 iterations.

The answer im supposed to get should give 12 iterations but I cant see why it wouldnt give the same answer.