Please post your solutions to the Nov 10 In-Class Exercise Thread.

Best,

Chris

<nowiki> #lang scheme (define (ip x y) (helper x y 0))

(define (helper x y n) (if (or (null? x) (null? y)) n (helper (cdr x) (cdr y) (+ n (* (if (number? (car x)) (car x) 0) (if (number? (car y)) (car y) 0)))))) </nowiki>

1 ]=> (define (iner-prod-aux l1 l2 list-so-far) (cond ((null? l1) list-so-far) (else (+ (* (car l1) (car l2)) (iner-prod-aux (cdr l1) (cdr l2) list-so-far))))) (define (iner-prod l1 l2) (iner-prod-aux l1 l2 0)) ;Value: iner-prod-aux

1 ]=> (iner-prod '(1 2 3) '(4 5 6))

;Value: iner-prod

1 ]=> ;Value: 32

<pre> (define (ipaux l1 l2 sum) (if (or (null? l1) (null? l2)) sum ;one or both of the lists is empty, so rest of numbers are treated as 0 (if (and (number? (car l1)) (number? (car l2))) (ipaux (cdr l1) (cdr l2) (+ sum (* (car l1) (car l2)))) ;both heads are numbers (ipaux (cdr l1) (cdr l2) sum) ;one or the other is not a number ) ) )

(define (ip l1 l2) (ipaux l1 l2 0)) </pre>

<nowiki>(define (ip L1 L2) (ip-aux L1 L2 0))

(define (ip-aux L1 L2 sum-so-far) (if (and (null? L1) (null? L2)) sum-so-far (ip-aux (cdr L1) (cdr L2) (add sum-so-far (product (car L1) (car L2))) )))

(define (product item-1 item-2) (cond ((eqv? #f (and (number? item-1) (number? item-2))) 0) ((eqv? #t (or (null? item-1) (null? item-2))) 0) (else (* item-1 item-2))))</nowiki>

(define (ip-acc L1 L2 innerProduct) (if (or (null? L1) (null? L2)) innerProduct (if (and (number? (car L1)) (number? (car L2))) (ip-acc (cdr L1) (cdr L2) (+ innerProduct (* (car L1) (car L2)) )); ) (define (ip L1 L2) (ip-acc L1 L2 0))

(define (ip L1 L2) (define result 0) (print (inner-product-helper L1 L2 result)))

(define inner-product-helper L1 L2 result (if (or(null? L1) (null? L2))) result (define a 0) (define b 0) (if (number? a) (let a (car L1)) (if (number? b) (let b L2)) (+ result (* a b)) (inner-product (cdr L1) (cdr L2) result)

(define (ip a b) (iphelp a b 0))

(define (iphelp a b c) (if (null? a) c (if (null? b) c (iphelp (cdr a) (cdr b) (+ c (* (car a) (car b)))))))

<nowiki>(define (ip-helper L1 L2 total) (if (null? L1) total (if (null? L2) total helper (cdr L1) (cdr L2) (+ total (* (car L1) (car L2))))))

(define (ip L1 L2) (ip-helper L1 L2 0))</nowiki>

(define (ipaux l1 l2 sum) (if (or (null? l1) (null? l2))

    (if (and (number? (car l1)) (number? (car l2)))
        (ipaux (cdr l1) (cdr l2) (+ sum (* (car l1) (car l2)))) 
        (ipaux (cdr l1) (cdr l2) sum) 
    )
)

)

(define (ip l1 l2) (ipaux l1 l2 0))