MATLAB: How to plot this

plotting

How do I plot the magnitude of a transfer function H?

Best Answer

It depends on the Toolbox you’re using.

For a filter using the Signal Processing Toolbox, use the freqz (link) or freqs (link on the freqz page) functions.

For a control system using the Control System Toolbox, use the bode (link) function. Note that it is essentially impossible to change any of the plot characteristics using bode, so if you want to customise the plot, get the outputs from bode and plot them using the subplot function.

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MATLAB: How can i plot the magnitude and phase response for given output

First, code the function you posted an image of. It would be best to create it as a transfer function object, using the tf function. See the relevant documentation for details.

Then, use the bode (link) or lsim (link) functions, depending on what you want to do.

Note that for a SISO system, you will have to use squeeze to plot the result, if you want to plot the outputs of bode and the others.

Example —

[mag,phase,wout] = bode(tfobj);
figure(3)
subplot(2,1,1)
semilogx(wout, 20*log10(squeeze(mag)), '-b', 'LineWidth',1)     % Bode Plot: Magnitude
ylabel('H(f) (dB)')
grid
subplot(2,1,2)
semilogx(wout, squeeze(phase), '-b', 'LineWidth',1)             % Bode Plot: Phase
xlabel('Frequency (rad/sec)')
ylabel('Phase (°)')
grid

MATLAB: How to change the default x-axis unit in a Bode diagram to Hertz

Use bodeplot (link) instead of bode.

It gives you that option, and the documentation specifically mentions that.

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Related Solutions

MATLAB: How can i plot the magnitude and phase response for given output

MATLAB: How to change the default x-axis unit in a Bode diagram to Hertz

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