Explorations with spreadsheets

                                          By Na Young

        

                 4.Generate a Fibonnaci sequence in the first column using

                                   f(0)=1, f(1)=1,

                                   f(n)=f(n-1)+f(n-2)

 

a.     Construct the ratio of each pair of adjacent terms in the Fibonnaci sequence.

What happens as n increase?  

Using excel we construct the Fibonnaci sequence and found some interesting points.

 As n increases, the ratio of each pair of adjacent terms became approached one number.

 The spreadsheet expressed it to 0.618933 We can say this convergence to one number.

           What about the ratio of every second term?

I could find the ratio of every second term also became approached one number 1.

 In the ratio of the second term is faster converged than the one of the each pair of adjacent terms.  

                                        

                  Excel file for Fibonnaci sequence

 

b.    Explore sequences where f(0) and f(1) are some arbitrary    integers other than 1.

 If f(0)=1 and f(1)=3, then your sequence is a Lucas Sequence. All such sequences,

however, have the same limit of the ration of successive terms.                  

 

                     Excel file for Lucas Sequence

 

 I constructed a Lucas Sequence and investigate the result. Like the Fibonnaci sequence,

the ratio of each pair of adjacent terms in it converged the same number in the Fibonnaci sequence.

 I investigated the ratio of every second term and found that it had the same limit

of  the second terms ratio of the Fibonnaci sequence. Moreover, in the Lucas Sequence,

second terms ratio converge to 1 faster than the Fibonnaci sequence.

 

 I had great interest that the convergence speed was faster as initial number was increased.

 So I tried to make a another sequence: f(0)=1 and f(1)=4. For my expectation

a result was similar to other sequences.  The ratio of successive terms had the same limit

of the Fibonnaci and Lucas sequence, and the ratio of second term also converged to 1.

 However, in the last experiment, the speed of convergence was not faster than a Lucas sequence.  

 

                       Excel file for other sequence    

 

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