fitting envelope peak points
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Ancalagon8
on 22 May 2020
Commented: Image Analyst
on 19 Jun 2020
I am facing some problems trying to create a fitting curve that will pass through maximum peaks. I tried findpeaks
findpeaks(Sig)
hold all
plot(Sig,'k')
![](https://www.mathworks.com/matlabcentral/answers/uploaded_files/297648/image.jpeg)
as well as envelope
[up, lo] = envelope(Sig,'peak');
plot(Sig, 'o-k');
hold on
plot(up,'r');
plot(lo,'b');
legend ('bb','up','down')
grid
![](https://www.mathworks.com/matlabcentral/answers/uploaded_files/297653/image.jpeg)
How can i create a fitting curve which will pass through max peak points? Will a solution be to export peaks into a new array, plot them and then create a fitting curve or there is another way?
Thanks in advance!
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Accepted Answer
Image Analyst
on 22 May 2020
Just try interp1() or spline(). Pass in your peak points and then the x values of the whole array, something like
[peakValues, indexes] = findpeaks(Sig);
yOut = spline(indexes, peakValues, 1:length(Sig));
plot(yOut, 'b-', 'LineWidth', 2);
grid on;
Let me know if it works. Attach your Sig data if it doesn't. Accept this answer if it does.
11 Comments
Image Analyst
on 18 Jun 2020
Yes. Did you try to change the model? It's not hard. See attached.
![](https://www.mathworks.com/matlabcentral/answers/uploaded_files/318537/image.png)
More Answers (1)
Ancalagon8
on 19 Jun 2020
Edited: Ancalagon8
on 19 Jun 2020
1 Comment
Image Analyst
on 19 Jun 2020
Wow, that's bizarre, but we've seen it before. See this link.
It seems to be related to the OpenGL renderer.
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