ex050600.m

来自「Matlab 6.0图形图像处理所附带的光盘」· M 代码 · 共 69 行

% Chapter 05: Example 05.06: Simple DFT Example

%

x = [1,1,1,1];

subplot(1,1,1);

%

% a) DTFT

w = [0:1:500]*2*pi/500;

[H] = freqz(x,1,w);

magH = abs(H); phaH = angle(H); phaH(126)=-47.5841*pi/180;

subplot(2,1,1); plot(w/pi,magH); grid

xlabel('frequency in pi units');

ylabel('|X|'); title('Magnitude of the DTFT')

subplot(2,1,2); plot(w/pi,phaH/pi*180); grid

xlabel('frequency in pi units');

ylabel('Degrees'); title('Angle of the DTFT')

%print -deps2 me0506a.eps

pause;subplot(1,1,1)

%

% b) 4-point DFT

N = 4; w1 = 2*pi/N; k = 0:N-1;

X = dft(x,N);

magX = abs(X), phaX = angle(X)*180/pi

subplot(2,1,1);plot(w*N/(2*pi),magH,'--'); 

axis([-0.1,4.1,-1,5]); hold on

stem(k,magX);

xlabel('k');

ylabel('|X(k)|'); title('Magnitude of the DFT: N=4')

hold off

subplot(2,1,2);plot(w*N/(2*pi),phaH*180/pi,'--');

axis([-0.1,4.1,-200,200]); hold on

stem(k,phaX);

xlabel('k');

ylabel('Degrees'); title('Angle of the DFT: N=4')

%print -deps2 me0506b.eps