# Average of a each vertical section of a stepped sawtooth wave

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Raj on 24 Mar 2021
Commented: Raj on 28 Mar 2021
Hello everyone. I need a help to find the average of each vertical steps in a stepped sawtooth wave. For clarity, I have attached the figure of sawtooth wave. Just to reiterate how can I find the average of each small vertical steps in the attached stepped sawtooth wave? Thank you for the help in advance.
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### Accepted Answer

Matt J on 25 Mar 2021
I would fit a line to the steps with polyfit, then find the intersections of the line fit with the vertical edges.
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Matt J on 25 Mar 2021
Edited: Matt J on 25 Mar 2021
x=linspace(0,10,1000); %Example staircase data
y=round(x);
p=polyfit(x,y,1);
yl=polyval(p,x);
idx=diff(sign(yl-y))<0;
xs=x(idx); ys=yl(idx);
plot(x,y,xs,ys,'ro')
Raj on 28 Mar 2021
Thank you so much for your clear explanation.

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### More Answers (1)

Greg Dionne on 25 Mar 2021
If you have the Signal Processing Toolbox, FINDCHANGEPTS is worth a look (it will give you the indices of each step of which you can take the average later -- see https://www.mathworks.com/matlabcentral/answers/313651-additional-findchangepts-function-output?s_tid=srchtitle for an example on how to extract each mean).
Otherwise see if you can get ISCHANGE to work.
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Raj on 25 Mar 2021
Thank you so much for your response. I have that tool box. However, I am not sure how to start with a code for my case. Could you please give me some pseudocode type sketch. I will attach a sample data if you need for this.
Greg Dionne on 25 Mar 2021
The example in "help findchangepts" should hopefully get you started.
If you post your data though, maybe another volunteer can come up with something even better!

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