How can I save variables from the loop?

I have a seismic data for each day from which I need to perform some calculation to recieve average amplitude for specific day. I have 240 such columns/days with 144000 amplitute datas. I am interested in the frecuency 4-14 Hz to find out the human activity seismic noise from that.

How can I make a 'for; loop to get this data calulated for the rest 240 day so that I also recieve/have it saved in matlab file an average amplitude of tyat speciefic day? I will have to plot this data against the days later on to see how the amplitude has changed with time.

The calculation for one day looks like this:

[amp,freq]=periodogram(detrend(seis(:,1)),[],[],Fs) %using periodogram I extract the amplitude and frequency of a data 
[Fr,Fc]=find(freq>=4 & freq<=14) %Get row and columns for which data between 4-14 Hz is true
plot(freq(Fr),amp(Fr)) %Plot the frequency and amplitude that fit 4-14 Hz range
av1=mean(amp(Fr)) %find the average amplitude that fits the range 47-14 Hz

%I need to have it calculated so that I get something like this for tyhe
%second day:
[amp2,freq2]=periodogram(detrend(seis(:,2)),[],[],Fs) 
loglog (freq2, amp2)
[amp2,freq2]=periodogram(detrend(seis(:,2)),[],[],Fs)
[Fr2,Fc2]=find(freq2>=4 & freq2<=14)
plot(freq2(Fr2),amp2(Fr2))
av2=mean(amp2(Fr2))
af2=mean(freq2(Fr2))

%For the third day and so on:
[amp3,freq3]=periodogram(detrend(seis(:,3)),[],[],Fs) 
loglog (freq3, amp3)
[amp3,freq3]=periodogram(detrend(seis(:,3)),[],[],Fs)
[Fr3,Fc3]=find(freq3>=4 & freq3<=14)
plot(freq3(Fr3),amp2(Fr3))
av3=mean(amp2(Fr3))
af3=mean(freq2(Fr3))

[Jan]

What is the relation between the question and the code? Over which value do you want to iterate the loop and which output should be collected?

Answer 1

[Walter Roberson]

% program before that, then

fieldname = "avg_results_" + day_number;
temp = struct(fieldname, av3);
save("YourFileOfResults.mat", "-struct", "temp", "-append");

This would create a new variable avg_results_### inside YourFileOfResults.mat

You might also want to have a look at matfile()

... But most of the time it is better to just accumulate all of the results and save them all at the end. You can probably pre-allocate the array of results, and it probably is not going to be very big.