Plotting linked double x-axis for one y-axis

I want to add a second x-axis to a plot, where the second x-axis is linked to the first x-axis with an inverse relation (eg. freq and wavelength). Thus the spacing on the second x-axis is not constant.

for example:

figure
hold on
x1 = 0:0.1:40;
x2 = 1./x1;
y = sin(x1)./(x1+2);
plot(x1,y,'Color','r')
% second x-axis for x2 here

I found a related example here https://www.mathworks.com/help/matlab/creating_plots/graph-with-multiple-x-axes-and-y-axes.html but it doesn't work for a linked double x-axis with a single y-axis. Also it only works with line.

Answer 1

[Ameer Hamza]

In MATLAB, there is no direct way to link two axes with the inverse relationship. However, a while ago, I answered a similar question: https://www.mathworks.com/matlabcentral/answers/509899-plot-with-two-related-x-axes. It changes the labels of top axes such that they appear to be linked. You can adapt that example according to your requirement. If you have any confusion, you can ask in the comment.

[Mohammadamir Ghaderi]

Thanks! Albeit I was hoping for an easier approach, but it works.

[Ameer Hamza]

I am glad to be of help.

Hopefully, they will add this feature in future releases.

[Ivan Bondarenko]

Matlab is such garbage