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#lang racket
(provide
make-vect
xcor-vect
ycor-vect
add-vect
sub-vect
scale-vect
test-vect
make-frame
origin-frame
edge1-frame
edge2-frame
test-frame
make-segment
start-segment
end-segment)
(require sicp-pict)
(require "lists.rkt")
(define (make-vect x y)
(cons x y))
(define (xcor-vect v)
(car v))
(define (ycor-vect v)
(cdr v))
(define (add-vect . v)
(make-vect
(fold-right + 0 (map xcor-vect v))
(fold-right + 0 (map ycor-vect v))))
(define (sub-vect . v)
(let ((xcors (map xcor-vect v))
(ycors (map ycor-vect v)))
(make-vect
(- (car xcors) (fold-right + 0 (cdr xcors)))
(- (car ycors) (fold-right + 0 (cdr ycors))))))
(define (scale-vect s v)
(make-vect (* s (xcor-vect v))
(* s (ycor-vect v))))
(define test-vect (make-vect 1 2))
(define (make-frame origin edge1 edge2)
(list origin edge1 edge2))
(define (origin-frame frame)
(car frame))
(define (edge1-frame frame)
(cadr frame))
(define (edge2-frame frame)
(caddr frame))
(define test-frame (make-frame
(make-vect 1 2)
(make-vect 2 4)
(make-vect 3 6)))
(define (make-segment start end)
(cons start end))
(define (start-segment s)
(car s))
(define (end-segment s)
(cdr s))
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