exa4_1.m

来自「<Matlab 7辅助信号处理技术与应用》的源码」· M 代码 · 共 29 行

% exa4-1_Butterworth for example4-1
% Buterworth analog lowpass filter prototype

clear all;
n=0:0.01:2;
for i=1:4
    switch i
        case 1
            N=2;
        case 2
            N=5;
        case 3
            N=10;
        case 4
            N=20;
    end
    [z,p,k]=buttap(N);
    [b,a]=zp2tf(z,p,k);
    [H,w]=freqs(b,a,n);
    magH2=(abs(H)).^2;
    hold on
    plot(w,magH2)
    axis([0 2 0 1]);
end
xlabel('w/wc');
ylabel('|H(jw)|^2');
title('Buterworth模拟原型滤波器');
grid on