master Yann Esposito (Yogsototh) 11 years ago
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2.47.scm

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 @ -0,0 +1,43 @@ (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)) (define one-one (make-vect 1 1)) (define xunit (make-vect 1 0)) (define yunit (make-vect 0 1)) (define half-half (make-vect 0.5 0.5)) ; ------------------------ (define (make-frame origin edge1 edge2) (list origin edge1 edge2)) (define (origin-frame f) (car f)) (define (edge1-frame f) (cadr f)) (define (edge1-frame f) (caddr f)) (print (make-frame origin xunit yunit)) (define (make-frame-cons origin edge1 edge2) (cons origin (cons edge1 edge2))) (define (origin-frame-cons f) (car f)) (define (edge1-frame-cons f) (car (cdr f)) (define (edge1-frame-cons f) (cdr (cdr f))