for loop for signal with changing conditions?

Hello, i need to create a for loop for the following orange signal with the first 2 negative peaks then 2 positive and so on

the problem is the for loop should only process the negative ones and not the positive peaks, and i really need a loop here with an if statement and cannot work with diff, find functions etc. because i want to extract specific values only in the negative peaks

my code so far, but i still get the values for the whole signal

for i=length(MomentRechts)%orange signal

if MomentRechts(i)<0;

MomR = find(diff(MomentRechts)>1000);

..

..

..

end

end

Thanks for everykind of help :)

Answer 1

[Jan]

Do you mean:

for i = 1:length(MomentRechts)
% Instead of:
for i´= length(MomentRechts)    

This command processes the complete signal:

MomR = find(diff(MomentRechts)>1000);

Maybe you want:

if MomentRechts(i) < 0
    index = find(MomentRechts(i:end) >= 0, 1);
    MomR  = find(diff(MomentRechts(i:index)) > 1000);    

But then you process this for each negative element again. This does not look useful.

Find the negative parts at first. Then process them block by block, not element by element.