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<html xmlns:mwsh="http://www.mathworks.com/namespace/mcode/v1/syntaxhighlight.dtd"> <head> <meta http-equiv="Content-Type" content="text/html; charset=utf-8"> <!--This HTML is auto-generated from an M-file.To make changes, update the M-file and republish this document. --> <title>sy3_fft_lp</title> <meta name="generator" content="MATLAB 7.0"> <meta name="date" content="2008-12-25"> <meta name="m-file" content="sy3_fft_lp"><style>body { background-color: white; margin:10px;}h1 { color: #990000; font-size: x-large;}h2 { color: #990000; font-size: medium;}p.footer { text-align: right; font-size: xx-small; font-weight: lighter; font-style: italic; color: gray;}pre.codeinput { margin-left: 30px;}span.keyword {color: #0000FF}span.comment {color: #228B22}span.string {color: #A020F0}span.untermstring {color: #B20000}span.syscmd {color: #B28C00}pre.showbuttons { margin-left: 30px; border: solid black 2px; padding: 4px; background: #EBEFF3;}pre.codeoutput { color: gray; font-style: italic;}pre.error { color: red;}/* Make the text shrink to fit narrow windows, but not stretch too far in wide windows. On Gecko-based browsers, the shrink-to-fit doesn't work. */ p,h1,h2,div { /* for MATLAB's browser */ width: 600px; /* for Mozilla, but the "width" tag overrides it anyway */ max-width: 600px; /* for IE */ width:expression(document.body.clientWidth > 620 ? "600px": "auto" );} </style></head> <body><pre class="codeinput"><span class="comment">%Â˳ýcos(2*pi/3*n)</span>omegap=pi/4;Apmax=3;omegar=2/3*pi;Armin=50;T=5*pi*10^(-6);wp=[omegap/pi];wr=[omegar/pi];[N,wc]=buttord(wp,wr,Apmax,Armin,<span class="string">'s'</span>);[b,a]=butter(N,wc,<span class="string">'low'</span>);sysl=tf(b,a)w=linspace(0,2*pi,500);h=freqz(b,a,w);length(h)mag=fftshift(20*log10(abs(h)));n=0:23;x=1+cos(pi/4*n)+cos(2*pi/3*n);X=fft(x,500);X1=fftshift(X);omega=2*pi/500*([0:499]);Y=fftshift(X.*h);title(<span class="string">'Ô­ÐźÅ'</span>);ylabel(<span class="string">'·ù¶È'</span>);xlabel(<span class="string">'ƵÂÊ'</span>);subplot(3,1,1);plot(omega,abs(X1));axis([0,2*pi,0,35]);title(<span class="string">'Â˲¨Æ÷·ùƵÏìÓ¦'</span>);ylabel(<span class="string">'Gain(dB)'</span>);xlabel(<span class="string">'Frequency(rad)'</span>);subplot(3,1,2);plot(w,mag);axis([0,2*pi,-100,5]);subplot(3,1,3);plot(omega,abs(Y));axis([0,2*pi,0,25]);</pre><pre class="codeoutput"> Transfer function: 0.00117 s^6 + 0.00702 s^5 + 0.01755 s^4 + 0.0234 s^3 + 0.01755 s^2 + 0.00702 s + 0.00117 -------------------------------------------------------------------------------- s^6 - 2.914 s^5 + 3.989 s^4 - 3.108 s^3 + 1.433 s^2 - 0.3663 s + 0.04031 ans = 500</pre><img vspace="5" hspace="5" src="sy3_fft_lp_01.png"> <p class="footer"><br> Published with MATLAB® 7.0<br></p> <!--##### SOURCE BEGIN #####%cos(2*pi/3*n)
omegap=pi/4;Apmax=3;
omegar=2/3*pi;Armin=50;
T=5*pi*10^(-6);
wp=[omegap/pi];wr=[omegar/pi];
[N,wc]=buttord(wp,wr,Apmax,Armin,'s');
[b,a]=butter(N,wc,'low');
sysl=tf(b,a)
w=linspace(0,2*pi,500);
h=freqz(b,a,w);
length(h)
mag=fftshift(20*log10(abs(h)));
n=0:23;
x=1+cos(pi/4*n)+cos(2*pi/3*n);
X=fft(x,500);
X1=fftshift(X);
omega=2*pi/500*([0:499]);
Y=fftshift(X.*h);
title('');
ylabel('路霉');xlabel('');
subplot(3,1,1);plot(omega,abs(X1));axis([0,2*pi,0,35]);
title('篓梅路霉矛');
ylabel('Gain(dB)');xlabel('Frequency(rad)');
subplot(3,1,2);plot(w,mag);axis([0,2*pi,-100,5]);
subplot(3,1,3);
plot(omega,abs(Y));axis([0,2*pi,0,25]);
##### SOURCE END #####--> </body></html>⌨️ 快捷键说明
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