#lang racket
(require rackunit
plot
"filter.rkt"
"filter-typed.rkt")
(provide (except-out (all-defined-out)
twopi i))
(define i (sqrt -1))
(define twopi (* 2 pi))
(define (response-plot poly min-freq max-freq)
(plot (line (lambda (x) ((response/mag poly) x)))
#:x-min min-freq
#:x-max max-freq
#:width 600))
(define (lpf-response scale min-freq max-freq)
(define fun
(response/mag
(coefficients->poly
(cons 1.0 (map (lambda (x) (* x -1.0))
(lpf-coefficients 1.0))))))
(plot (line (lambda (x) (fun x)))
#:x-min min-freq
#:x-max max-freq
#:width 600))