Taylor Polynomials: generate them in Racket

taylor.rkt

(require plot)

(define (factorial n)
  (if (< n 2) 1 (* n (factorial (- n 1)))))

(define (taylor-poly func n c)
  (define (calc-coeff dfn level)
    (/ (dfn c) (factorial level)))
  (define (find-coeff fn level coeffs)
    (if (= level (+ n 1))
        coeffs
        (find-coeff (derivative fn) (+ level 1)
                    (append coeffs (list (calc-coeff fn level))))))
  (find-coeff func 0 '()))

(taylor-poly sin 4 0)
; '(0 1.0 0.0 -0.5551115123125783 0.0)