vertical line in plot

but i receive an error message, any help?

Also, how do i label the line?

[Jambo]

this is the error: Undefined function 'vline' for input arguments of type 'double'.

Answer 1

[Fangjun Jiang]

I don't think vline() is a MATLAB built-in function. You can use line() though.

x=100*(1:10);
y=1000*(1:10);
semilogx(x, y);
line([300 300],[2000,6000]);

[Jambo]

thanks, how do i label the line?

[Fangjun Jiang]

You can use text(). FYI, you may get the vertical line you wanted by adding "grid on". You may also consider xlabel()

Answer 2

[Star Strider]

You did not post your complete code.

The bode function generally allows you to make only a small number of modifications, all of which are listed in the documentation for it.

The easiest way to do what you want is to get the outputs from bode, then plot them as normal subplots. To label the vertical line, use the text function.

Example —

H = tf([1 0.1 7.5],[1 0.12 9 0 0]);

[mag,phase,wout] = bode(H);

figure(2)
subplot(2,1,1)
semilogx(wout, squeeze(mag))
hold on
plot([1 1]*5, ylim, '--r')
hold off
text(5, mean(ylim), '\leftarrow \omega = 5')
grid
subplot(2,1,2)
semilogx(wout, squeeze(phase))
hold on
plot([1 1]*5, ylim, '--r')
hold off
text(5, mean(ylim), '\leftarrow \omega = 5')
grid

EDIT — Added text calls to label the line.