exa2_6.m

matlab应用实例。如：FIR、IIR数字滤波器设计等。

% exa2-6_circle_conv.m, for example 2-6
% to test circle_conv.m

clear;
x1=[1 2 3 4 5];
x2=[1 2 3 4 5 4 3 2 1];
N=length(x1)+length(x2)-1;
n=0:N-1;
n1=0:N-2;
n2=0:N-3;
y1=circconv(x1,x2,N);
y2=circconv(x1,x2,N-1);
y3=circconv(x1,x2,N-2);
x1=[x1 zeros(1,N-length(x1))];
x2=[x2 zeros(1,N-length(x2))];
Xf1=dft(x1,N);
Xf2=dft(x2,N);
Xf=Xf1.*Xf2;
x=idft(Xf,N);
x=real(x);
subplot(231)
stem(n,x1)
title('x1(n)')
subplot(232)
stem(n,x2)
title('x2(n)')
subplot(233)
stem(n,x)
title('x(n)=IDFT(X(k))')
subplot(234)
stem(n,y1)
title('N点圆周卷积')
subplot(235)
stem(n1,y2)
title('N-1点圆周卷积')
subplot(236)
stem(n2,y3)
title('N-2点圆周卷积')