sicp exercise 2.46

;; Exercise 2.46.  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:

;;



(define (make-vect x y) (cons x y))
(define (xcor-vect vect) (car vect))
(define (ycor-vect vect) (cdr vect))


(define (add-vect vect1 vect2)
  (let ((x1 (xcor-vect vect1)))
       ((x2 (xcor-vect vect2)))
       ((y1 (ycor-vect vect1)))
       ((y2 (ycor-vect vect2)))
    (make-vect (+ x1 x2) (+ y1 y2))))

(define (sub-vect vect1 vect2)
  (let ((x1 (xcor-vect vect1)))
       ((x2 (xcor-vect vect2)))
       ((y1 (ycor-vect vect1)))
       ((y2 (ycor-vect vect2)))
    (make-vect (- x1 x2) (- y1 y2))))

(define (scale-vect vect s)
  (let ((x (xcor-vect vect)))
       ((y (ycor-vect vect)))
    (make-vect (* s x) (* s y))))