Problem in plotting using semilogx() function

PVR
2014 10 19
1 个回答
回答已采纳
更新时间：2014 10 19
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I need to plot a graph between w(frequency) and Mdb(Magnitude in db) using semilogx() function for different values of w. The output of graph is null. It shows nothing and there are no errors displayed. Where did I go wrong.
R=zeros(1,10000);
I=zeros(1,10000);
Mag=zeros(1,10000);
Z=zeros(1,10000);
Y=zeros(1,10000);
Mdb=zeros(1,10000);
for *w* = 0.1:0.01:10
R=(256-(16*w^2))/((16-(w^2))^2+(10*w)^2);
I=-160*w/((16-w^2)^2+(10*w)^2);
Mag=sqrt(R^2+I^2);
Z=atan2(I,R);
Y=Z*180/pi;
*Mdb* =20*log10(Mag); *bold*
plot(w,Mdb,'g');
semilogx(w,Mdb);
end

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 采纳的回答

Rick Rosson
Rick Rosson 2014-10-19
编辑：Rick Rosson 2014-10-19

1 个投票

Vectorized code, no for-loop necessary:
w = 0.1:0.01:10;
R = (256-(16*w.^2))./((16-(w.^2)).^2+(10*w).^2);
I = -160*w./((16-w.^2).^2+(10*w).^2);
X = complex(R,I);
Mag = abs(X);
Mdb = 20*log10(Mag);
phi = angle(X)*180/pi;
figure;
ax(1) = subplot(2,1,1);
semilogx(w,Mdb);
grid on;
xlabel('Frequency');
ylabel('Magnitude in dB');
ax(2) = subplot(2,1,2);
semilogx(w,phi);
grid on;
xlabel('Frequency');
ylabel('Phase angle in degrees');
linkaxes(ax,'x');

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