How to insert two X axis in a Matlab a plot

Question

I would like create a Matlab figure with a double X axis (m/s and km/h) with the same plot.

I have found plotyy and - in Matlab reposity - plotyyy, but I am looking

Answer 1

As a very simple alternative you could also create a 2nd axis (transparent) and put it below the first one so that you only see the x axis.

Example:

clear
clc
close all

x = 1:10;

x2 = x/3.6;

y = rand(size(x));

hP1 = plot(x,y);

a1Pos = get(gca,'Position');

%// Place axis 2 below the 1st.
ax2 = axes('Position',[a1Pos(1) a1Pos(2)-.05 a1Pos(3) a1Pos(4)],'Color','none','YTick',[],'YTickLabel',[]);

%// Adjust limits
xlim([min(x2(:)) max(x2(:))])

text(2.85,0 ,'m/s','FontSize',14,'Color','r')
text(2.85,.05 ,'km/h','FontSize',14,'Color','r')

Output:

Then you can manually add the x labels for each unit, in different color for example.