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 `(load "displaylib.scm")` `(title "Exercise 2.46")` `(doc "A two-dimensional vector v running from the origin to a point can be represented as a pair consisting of an x-coordinate and a y-coordinate. Implement a data abstraction for vectors by giving a constructor make-vect and corresponding selectors xcor-vect and ycor-vect. In terms of your selectors and constructor, implement procedures add-vect, sub-vect, and scale-vect that perform the operations vector addition, vector subtraction, and multiplying a vector by a scalar:` ` ` ` (x1,y1) + (x2,y2) = (x1+x2 , y1+y2)` ` (x1,y1) - (x2,y2) = (x1-x2 , y1-y2)` ` s . (x,y) = (sx, sy)` ` ")` ``` ``` `(define (make-vect x y) (list x y))` `(define (xcor-vect v) (car v))` `(define (ycor-vect v) (cadr v))` `(define (add-vect v w) (make-vect ` ` (+ (xcor-vect v) (xcor-vect w)) ` ` (+ (ycor-vect v) (ycor-vect w))))` `(define (sub-vect v w) (make-vect ` ` (- (xcor-vect v) (xcor-vect w)) ` ` (- (ycor-vect v) (ycor-vect w))))` `(define (scale-vect s v) (make-vect ` ` (* s (xcor-vect v)) ` ` (* s (ycor-vect v))))` ``` ``` `(define origin (make-vect 0 0))` `(display origin)(newline)` ``` ``` `(define one-one (make-vect 1 1))` `(define half-half (make-vect 0.5 0.5))` ``` ``` `(print "(add-vect one-one half-half)")` `(display (add-vect one-one half-half))(newline)` `(print "(sub-vect one-one half-half)")` `(display (sub-vect one-one half-half))(newline)` ``` ``` `(display "(scale-vect .75 one-one)")(newline)` `(display (scale-vect .75 one-one))(newline)` ``` ``` ``` ``` ``` ```