Help with my fibonacci sequence code

0, 1, 1, 2, 3, 5, 8, 13, 21, 34, ... (add previous two numbers together for the next in the sequence)

1. Use a for-end statement to find the 100th number in the sequence.

2. Update this script using a while statement to find the first number in the sequence that has six digits.

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This is my code until now.

% fibonacci

a=0; b=1; n=input('Enter no, of terms: ');

for i=1:n fprintf('%d',a); fprintf('\t') c=a+b; a=b; b=c;

end

I'm not sure if is correct. But the assignment require to find the 100th number with a for-end and the other part is to find the sequence that has six digits.

[Abhishek]

it is correct

[John D'Errico]

@Abhishek - actually, it is not correct. It does not solve the assignment. And while it does appear to compute Fibonacci numbers, the code does not do what was required.

Answer 1

[Jim Riggs]

This is how I did it. This function will give the nth number in the Fibonacci sequence:

function f=fib(n)
  s=[1, 1];
  if n>2
      for i=3:n
         s(i) = s(i-1)+s(i-2)
      end
   end
f = s(n)
end

The number of digits in a number, n, is

floor(log10(n))+1

so you can write a loop:

n=1;
nd=1;
while nd < 6
    n=n+1
    fn = fib(n)
    nd = floor(log10(fn))+1;
end

When this loop ends, fn is the first Fibonacci number with 6 digits, and it is the nth in the sequence.