How can I improve my plots including a dashed line

Hello, I am developing a code where I need to create a plot that incorporates fitted values on a semi-logarithmic scale on the x-axis, but I also need to insert a dashed line in the center of the plot (when y = 0). I am attaching an example of how I am doing it, but the line is not being displayed in the figure.

figure
semilogx(data_resi_inter.PGA1100,delta_ij_inter,'^r');
hold on
plot([0 0.6],[0 0],'k--','LineWidth',1.0) % dashed line
title('Delta term vs PGA1100');
subtitle('for Interface EQs & T = PGA');
ylabel('Delta_{ij}');
xlabel('PGA1100 [g]');
grid on

On the other hand, I would like to know if there is a way to make all the figures (which in my case are 6 of the same type) appear on the screen at the same time, without having to close one to see the next.

I have already used the 'subplot' function, but I also need to use the 'print' command, and the figures are not saved with sufficient quality for proper viewing.

Answer 1

[Walter Roberson]

semilogx(data_resi_inter.PGA1100,delta_ij_inter,'^r');

The x axis is being set to log.

plot([0 0.6],[0 0],'k--','LineWidth',1.0) % dashed line

You ask to plot starting from 0 on a log x axis. That is an implicit request to plot from -infinity (log(0) == -infinity). No line will be drawn when a coordinate is nan or inf.

You need to start your plot from a positive real coordinate.

[Ivan]

Thank you very much Walter, i didn't think about that..

any idea with the other problem?

[Voss]

An alternative way to plot a horizontal line is to use the yline function, which works on log or linear scale without having to specify x-coordinates at all.

figure
semilogx(1:100,-40:59)
yline(0,'k--')

[Walter Roberson]

I have already used the 'subplot' function

You could try instead using tiledlayout and exportgraphics

[Sam Chak]

Ivan, do you need to create the six tiled plots in a sequential order, with a running number that also needs to be printed in the title of each plot?

Also, do you wish to print a symbolic Delta character on the y axis label?

One last thing — Is there any relationship between each tiled plot that would warrant drawing a connecting line between two adjacent plots to highlight specific features, such as intersection points? Would you like to label these intersection points?

[Sam Chak]

Ah, I forgot to ask: Would you also like to plot the individual points to highlight the aesthetic appeal of how the thicc curve fits the data points?

[Ivan]

Hello Sam, thanks for asking.

In the first place, i would like to create six plots and save those in a good quality image and proper viewing.

The 6 plots can be stored in a single image, as long as they are clearly visible.

In another case, I would at least like the plots to be displayed simultaneously in MATLAB when generating the images, so I don't have to close one image to view another.

I have 3 plots for one type of scenario and 3 plots for another, and each of the 3 plots corresponds to the term 'delta_ij,' but compared with different variables.

And yes! if you can help me with including delta character on the Ylabel it would be great!

[Ivan]

And if you know anything about the error bars shown in the image, that would also be very helpful.

[Sam Chak]

Hi @Ivan

You can learn more in the documentation of ylabel():

https://www.mathworks.com/help/matlab/ref/ylabel.html#buiyzbx-1_sep_shared-Interpreter

However, plotting error bars is uncommon in my field, as most phenomena can be modeled with deterministic mathematical equations, provided they align with the governing equations of physics. Therefore, insignificant errors are often neglected, as they typically do not pose a threat to human safety or asset value. Moreover, there are predictive and corrective algorithms available as backups.

Have you not found any information about error bars on mathworks.com?