I'm getting "Index exceeds array bounds." and I'm not sure how to fix it.

Here's the problem.

One interesting property of a Fibonacci sequence is that the ratio of the values of adjacent members of the sequence approaches a number called “the golden ratio” or Φ (phi). Create a program that accepts the first two numbers of a Fibonacci sequence as user input, then calculates additional values in the sequence until the ratio of adjacent values converges to within 0.001. You can do this in a while loop by comparing the ratio of element k to element k – 1, and the ratio of element k – 1 to element k – 2. If you call your sequence x, then the code for the while statement is

 whileabs(x(k)/x(k−1) − x(k−1)/x(k−2))+0.001

This is my code.

%9.8

first_input = input('Enter the first number ');

second_input = input('Enter the second number ');

x(1)=first_input;

x(2)=second_input;

k=3;

while abs((x(k)/x(k-1)) - (x(k-1)/x(k-2)))>0.001

      x(k)=x(k-2)+x(k-1);
      k=k+1;
  end
  disp(x)

Answer 1

[Walter Roberson]

You need to calculate x(3) from x(1) and x(2) before you start the while loop.

[Benjamin Scott]

I still get the same error. Even when I say x(3)=2. Maybe I don't understand what you mean?

first_input = input('Enter the first number ');

second_input = input('Enter the second number ');

x(1)=first_input;

x(2)=second_input;

k=3;

   x(3)=x(k-2)+x(k-1);
  while abs((x(k)/x(k-1)) - (x(k-1)/x(k-2)))>0.001

      x(k)=x(k-2)+x(k-1);
      k=k+1;
  end

[Walter Roberson]

When k = 3, you assign to x(k) which is x(3), which already has a value. Then you increment k to 4 and try to access x(k) which is x(4) which has not been defined.

Hint: move the increment of k to before the assignment.

[Benjamin Scott]

gotcha. Thank you that worked.