%例程4－22   Ⅰ、Ⅱ型理想帶阻濾波器的單位沖激響應 計算

function hd=ideal_bs(Wcl,Wch,N)
%compute the ideal bandstop fiter unit pulse respondence hd(n)
%wcl: low cutoff frequency
%wch: high cutoff frequency
%N: window length
%hd: unit pulse respondence

alpha= (N-1)/2;
n=0:1:N-1;
m=n-alpha+eps;
hd=[sin(Wcl*m)+sin(pi*m)-sin(Wch*m)]./(pi*m);