On the implementation of the Fibonacci seq.

We all enjoy showing off how elegant our implementation of the Fibonacci sequence is in Haskell or Scheme or whatever.  But, frankly, they suck.  Even if you're using tail recursion to avoid fucking up the stack it's still terribly inefficient.

Here is the correct way to implement the Fibonacci sequence (in Scheme):
(define (fibonacci x)
    (let  ((phi (/ (+ 1 (sqrt 5)) 2)))
    (+ (/ (+ (expt phi x) (expt (- 1 phi) (- x 2))) (+ (expt phi 2) 1)) (/ (- (expt phi (- x 1)) (* phi (expt (- 1 phi) (- x 2)))) (+ (expt phi 2) 1)))))

>>1
[1]> (defun fibonacci (x)
    (let  ((phi (/ (+ 1 (sqrt 5)) 2)))
    (+ (/ (+ (expt phi x) (expt (- 1 phi) (- x 2))) (+ (expt phi 2) 1)) (/ (- (expt phi (- x 1)) (* phi (expt (- 1 phi) (- x 2)))) (+ (expt phi 2) 1)))))
FIBONACCI
[2]> (fibonacci 1)
1.0
[3]> (fibonacci 3)
2.0
[4]> (fibonacci 4)
3.0000005
[5]> (fibonacci -1)
0.99999994
[6]> (fibonacci 183)
7.8569633E37
[7]> (fibonacci 184)

*** - floating point underflow
The following restarts are available:
ABORT          :R1      ABORT
Break 1 [8]>
Oh, my. Here's how I would implement a function with identical output and range in C:
float fibonacci(int n) {
        return fibonacci_table[n];
}