%dc系數的dpcm% Differential Pulse Coded Modulationfunction r = dc_dpcm(x)%最簡單的預測a = [1];% x: 輸入列向量% a: 預測濾波器（系數）列向量% r: 取整后的差分編碼輸出% before: 過去值序列% now: 當前預測值%獲取信號長度和濾波器長度m = length(x);  p = length(a);%與濾波器長度對應的前P個值直接輸出r = round( x(1:p) );%預測序列初始值before = r;%預測濾波循環for t=p+1:m,   now(t)=a'*before(t-1:-1:t-p);   r(t)=round(x(t)-now(t));   before(t)=now(t)+r(t);end