Finding abrupt changes in the data

I'm trying to use the ischange function to find abrupt changes in my data however the function seems to be missing a prominent change. The data at x= 115 (in the plot) drops off sharply and I want to capture this value for other steps in the processing. Basically, I want to find the distance between the peak at X=15 and the sharp drop at X=115. I have tried the various parameters and can not get the code to recognize this region as an abrupt change in the data. Do you have any suggestion? My version is 2022b.
my code from Live Editor:
DFe=DF(1,75:200);
[TF3,S13] = ischange(DFe(1,:),'linear','MaxNumChanges',3);
JX = find(TF3);
JY = DFe(TF3);
figure; plot(DFe(1,:)); hold on
plot(JX,JY,'*')

2 Comments

From the screen shot, it looks like it found the drop at index 115.
If anyone should investigate, they'll need your data. Please upload your data (e.g., variables(s) saved to a mat-file) using the paperclip button.
finding the first peak could also be easily achieved with max
finding the drop can probably be found by finding the point of maximum negative slope

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R2022b

Asked:

on 8 Mar 2024

Commented:

on 11 Mar 2024

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