#lang racket
 
(require plot (only-in srfi/41 stream-map))
(plot-new-window? #t)
 
(define-values (*m* *k* *dt*) (values 1 10 0.01))
 
(define *v*
  (stream-cons 0
               (stream-map (lambda (v x)
                             (- v (* (/ *k* *m*) x *dt*))) *v* *x*)))
 
(define *x*
  (stream-cons 1
               (stream-map (lambda (x v)
                             (+ x (* v *dt*))) *x* (stream-rest *v*))))
 
(define *xs* (stream->list (stream-take *x* 500)))
(define *ts* (map (lambda (x) (* x *dt*)) (range 500)))
(plot (lines (map vector *ts* *xs*))
      #:x-label "t" #:y-label "x" #:title "t-x")

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