problem in applying loop

Q
Quincy · Dec 4, 2020 · 1.9K views
Question
I have emg signal (30000x4) and want to apply function on it in loop....     function waveLen = find_waveform_length(signal) sum=0; for i=2:length(signal) sum= sum + abs(signal(i)-signal(i-1)); end waveLen = sum;     %%%%%% New file %%%%%%% load ('dath001.mat'); x = dath001; % 30000x4 for i = 1:4 waveLen(i) = find_waveform_length(x(i)) end   but it give output of 0 0 0 0 instead if i run waveLen function separately it give output of 463.6428 200.0671 411.7511 372.9306 ... I want this output by simple apply loop command
Expert Answer
Profile picture of John Michell
John Michell PhD Expert
Answered Nov 20, 2025

What is the 'y' you have used in your main script loop? Its not defined anywhere. Use this line in main script:

 

waveLen(i) = find_waveform_length(x(:,i))
Since you have not shared your MAT file, I tried with a random 30000x4  matrix and it works.
Few other recommendations:
1) Put an 'end' for your function
2) Don't use variable 'i' or any other inbuilt Matlab variable as index in your 'for' loop.
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