Plotting horizontal line with semilogx graph

I have encountered a problem with graph plotting in Octave.

So the situation looks like that:
I have to graph a relationship where x axis is in logarythmic scale , so i used semilogx and it worked fine.
Then I need add a straight horizonalt line at certain value that crosses the main graph.
How can i plot that line with the main graphs?

I tried to look it up online but im still not sure how to do it.

It also seems like the second figure is also in log scale.

Thanks in advance for the answers,
Ben11V.m (288 Bytes)

What about immediately following the code by this line ?
semilogx (freq ([1,end]), [z,z]);

1 Like

Thank You for the solution.