Chapter 1, Building Abstractions with Procedures

Section - Formulating Abstractions with Higher-Order Procedures

Exercise 1.35


From sec-1.2.2, we know that:

${ \phi }^2 = 1 + \phi$
Dividing both sides by $\phi$, we get: $\phi = { \frac 1 \phi } + 1$.

This is the same equation given in the problem. Thus golden ration $\phi$ is indeed the fixed point of the transformation $x \mapsto 1 + { \frac 1 x }$.

1
2
> (fixed-point (lambda (x) (+ 1 (/ 1 x))) 1.0)
1.6180327868852458