# How to plot 3 y axis?

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SOMNATH MAHATO on 13 Nov 2021
Edited: TADA on 13 Nov 2021
x = [1 6 10 15 22];
y1 = [2 6 8 10 15];
y2 = [99 97 94 92 89];
y3= [1 3 6 8 11];
Do you mean three lines, or three axes with different units?

Cris LaPierre on 13 Nov 2021
I would probably plot this way.
x = [1 6 10 15 22];
y1 = [2 6 8 10 15];
y2 = [99 97 94 92 89];
y3= [1 3 6 8 11];
plot(x,[y1;y2;y3]')
Given the different scale of y2, I might also do it using yyaxis
figure
yyaxis left
plot(x,[y1;y3]')
yyaxis right
plot(x,y2)
The apostrophe transposes the row vectors into column vectors. MATLAB treats columns as data series, so if I have one x vector and multiple y variables, it's a way to plot them all in a single command.
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I would prefer to keep everything on a single axis, unless these are actually different measures (like mass and height, or whatever). If you keep everything on a single axis, you can more easily compare values, slopes, etc.
The different sizes can then be managed by either a logarithmic scale (not the best option here) or a broken axis ( https://www.mathworks.com/matlabcentral/fileexchange/21864-breakplot ), which is the best option for displaying these data in my opinion.