1 ;; The first three lines of this file were inserted by DrScheme. They record metadata
2 ;; about the language level of this file in a form that our tools can easily process.
3 #reader(lib "htdp-advanced-reader.ss" "lang")((modname |29.3|) (read-case-sensitive #t) (teachpacks ((lib "draw.ss" "teachpack" "htdp") (lib "arrow.ss" "teachpack" "htdp") (lib "gui.ss" "teachpack" "htdp"))) (htdp-settings #(#t constructor repeating-decimal #t #t none #f ((lib "draw.ss" "teachpack" "htdp") (lib "arrow.ss" "teachpack" "htdp") (lib "gui.ss" "teachpack" "htdp")))))
4 ;norm : vector -> number
5 ;Produces the square root of the sum of the numbers in avector.
6 
7 (define (norm avector)
8   (sqrt (sum-of-squares avector 0)))
9 
10 ;sum-of-squares : vector N -> number
11 ;Given avector and i, square the element in avector from [i,vector-length) and then sum them 
12 
13 (define (sum-of-squares avector i)
14   (cond
15     [(= (vector-length avector) i) 0]
16     [else (+ (sqr (vector-ref avector i))
17              (sum-of-squares avector (add1 i)))]))
18 
19 ;vector-contains-doll? : (vectorof symbols) -> boolean
20 ;Given avector, determine if it contains 'doll.
21 
22 (define (vector-contains-doll? avector)
23   (vector-contains-doll?-aux avector 0))
24 
25 ;vector-contains-doll?-aux : (vectorof symbols) N -> boolean
26 ;Given avector and i, determine if avector contains 'doll.
27 
28 (define (vector-contains-doll?-aux avector i)
29   (cond
30     [(= (vector-length avector) i) false]
31     [else (or (symbol=? (vector-ref avector i) 'doll)
32               (vector-contains-doll?-aux avector (add1 i)))]))
33 (define vector2 (vector 'robot
34                         'car
35                         'eraser
36                         'pen
37                         'motorcycle
38                         'bicycle
39                         'helmet
40                         'monitor
41                         'dolly
42                         'policeman
43                         'diamond))
44 (vector-contains-doll? vector2)