# SICP Exercise 1.35

Code

```
#lang racket
(require math/base)
;; Fixed points
(define tolerance 0.00001)
(define (fixed-point f first-guess)
(define (close-enough? v1 v2)
(< (abs (- v1 v2)) tolerance))
(define (try guess)
(let ((next (f guess)))
(if (close-enough? guess next)
next
(try next))))
(try first-guess))
; tests
(display "calculated")
(newline)
(fixed-point (lambda (x) (+ 1 (/ 1.0 x))) 1)
(display "exact")
(newline)
phi.0 ; exact
```

Output

```
calculated
1.6180327868852458
exact
1.618033988749895
```