Why is it that so many times, even among good programmers, the Fibonacci function is misimplemented?<p>Here it is from the OCaml tutorial:<p><<#let rec fib n =
# if n < 2 then 1 else fib(n-1) + fib(n-2);;
val fib : int -> int = <fun><p><pre><code> #fib 10;;
- : int = 89</code></pre>
>><p>Finonacci 0 is 0, not 1.
Thus: Fibonacci 10 is 55.<p>Corrected:<p># let rec fibo n =
# if n < 2 then if n ==1 then 1 else 0 else fibo(n-1) + fibo(n-2);;
val fibo : int -> int = <fun>
# fibo 12;;
- : int = 144
# fibo 10;;
- : int = 55
#<p>(And yes it is a superslow exponential implementation but that is not the point here.)
I think that's the case because the Fibonacci sequence isn't interesting as a sequence itself to most developers, but as an example of basic recursion. And as an example of basic recursion, you can have a base case be slightly off without misrepresenting what the essence is.
Perhaps because in the <i>original</i> (Sanskrit) implementation, Fib(10) = 89?<p><a href="http://en.wikipedia.org/wiki/Fibonacci_number" rel="nofollow">http://en.wikipedia.org/wiki/Fibonacci_number</a>