why this line gives error?

I have a code in which there is an error:

%% 
212    % Range
213    Range_hat(1) = Ranges(snapstart(1));
214    Rangebin_hat(1) = RangeBins(Ranges == Range_hat(1));
215    % DOA
216    [betapks,DOAidx] = findpeaks(beta(snapstart(1),80:end)); % a possible DOA range is applied  1 ~ 101 degrees
217    
218    [betapks,id_temp] = sort(betapks,'descend');
219    DOAidx = DOAidx(id_temp)+79;
220    beta_pks(1) = betapks(1);
221    DOA_hat(1) = theta(DOAidx(1));
    

After running , the above section gives the following error:

Index exceeds the number of array elements (0).

Error in DataA_main1 (line 220)

beta_pks(1) = betapks(1);

Answer 1

[Yazan]

It seems that the findpeaks function could not find a peak, so it returned an empty vector. Check your signal, or specify some parameters for findpeaks.

[Sadiq Akbar]

Thanks alot for your response. But how?

[Yazan]

How what?

[Sadiq Akbar]

I mean I have already supplied the arguments beta(snapstart(1),80:end) which is a 1 x 101 array having all values of -200. So what should I change?

[Image Analyst]

@Sadiq Akbar, here is another chance to read the posting guidelines:

TUTORIAL: How to ask a question (on Answers) and get a fast answer

or you can click the Community Guidelines link on this page.

When you do you'll notice that one thing it says to do is to attach your data so people can help you -- something you have not done yet (so that's how I know you didn't read the guidelines). After you do, people will see your signal (if you also post a screenshot of it plotted) and will be able to help you more and better.

save('answers.mat', 'Ranges', 'theta', 'snapstart');

[Sadiq Akbar]

Thank you for your response. Yes you are right, but since my file is in GBs, so cannot upload it.

Answer 2

[Image Analyst]

Can't you crop out a portion of it that demonstrates the error and upload that?

What are these values? Put in this code after findpeaks()

sizeOfBeta = size(beta) % Don't use a semicolon
fprintf('snapstart(1) = %f.\n', snapstart(1));
if isempty(betapks)
    fprintf('There were no peaks found!\n');
    uiwait(warndlg('There were no peaks found!'));
end

What do you see?