Question

I’m trying to expand a simple fibonacci function, and I need to use the values for each term more than once. So, I figured I’d use let to hold onto the values. But, I’m not getting what I think I should out of the function.

Here is the original fib function:

(define (fib n)
  (if (< n 2)
      n
      (+ (fib (- n 1)) (fib (- n 2)))))

Here is my attempt at doing the same thing, but with let:

(define (fib-with-let n)
  (if (< n 2)
      0
      (let ((f1 (fib-with-let (- n 1)))
            (f2 (fib-with-let (- n 2))))
        (+ f1 f2))))

Results:

> (fib 10)
55
> (fib-with-let 10)
0

Thanks!

Answer 1

You made a typo:

(if (< n 2)
    0
    ...)

You mean n.