freqDomainAmp :: [Double]
freqDomainAmp = let (h : t) = freqDomain
                    (m, l) = splitAt (length t - 1) t in
  (magnitude h / 2) : (map magnitude m) ++ (map ((/2) . magnitude) l)
freqDomainAmp :: [Double]
freqDomainAmp = let (h : t) = freqDomain
                    (m, l) = splitAt (length t - 1) t in
  (magnitude h / 2) : (map magnitude m) ++ (map ((/2) . magnitude) l)
freqDomainAmp = let (h : t) = freqDomain
                    (m, l) = splitAt (length t - 1) t in
  (magnitude h / 2) : (map magnitude m) ++ (map ((/2) . magnitude) l)