MATLAB: Control system bode plot

bode plot

how to plot this two equatio and the resutant output is shown in the figure
the alpha value should be any fractional value(eg-alpha=0.01 to 0.09).
one of the matlab community person helped me but his alpha value is 1 not fractional the code is given below
(hold off;
alpha=1;Wcr=10;
w1=logspace(-1,log10(Wcr),1000);w2=logspace(log10(Wcr),3,1000);
Mag1=20*ones(1,numel(w1));Mag2=@(w2) 20*alpha*log10(w2);
semilogx(w1,Mag1);hold on;semilogx(w2,Mag2(w2));grid on;xlabel('Frequency');ylabel('dB'))

Best Answer

Check this:
alpha=0.1; % alpha is 0.1
Wcr=10;
w1=logspace(-1,log10(Wcr),1000);
w2=logspace(log10(Wcr),3,1000); 
Mag1=20*alpha*ones(1,numel(w1)); %<---- you need to multiply alpha here too
Mag2=@(w2) 20*alpha*log10(w2);
semilogx(w1,Mag1);
hold on;
semilogx(w2,Mag2(w2));
grid on;
xlabel('Frequency');
ylabel('dB')
Also try this to plot all values from 0.1 to 0.9 on one graph
Wcr=10;
w1=logspace(-1,log10(Wcr),1000);
w2=logspace(log10(Wcr),3,1000); 
ax = axes('XScale', 'log');
hold on;
Alpha=0.1:0.1:0.9;
for i=1:numel(Alpha)
    alpha = Alpha(i);
    Mag1=20*alpha*ones(1,numel(w1));
    Mag2=@(w2) 20*alpha*log10(w2);
    semilogx(w1,Mag1);
    semilogx(w2,Mag2(w2));
end
grid on;
xlabel('Frequency');
ylabel('dB');
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