How to get a period of cosinus function ?
5 visualizzazioni (ultimi 30 giorni)
Mostra commenti meno recenti
Hi,
I have to find the period of the cosinus function using only the vector time and the vector data of the function.



2 Commenti
Rik
il 25 Mag 2020
This looks like the sum of two cosines, not just one. Do you want the cosine with the largest magnitude? Are you allowed to use a Fourrier transform?
Risposta accettata
Rik
il 25 Mag 2020
Modificato: Rik
il 25 Mag 2020
Because this is homework, I won't provide a copy-paste ready solution.
If you follow the example from the documentation for fft, you get the code below.
%recreate data
delta_t=0.1;Tlim=5;f=[1;2];
t=0:delta_t:Tlim;
x=sum(cos(2*pi*t.*f));
%figure(1),clf(1)
%plot(t,x)
Fs=1/mean(diff(t));%sampling frequency
L=numel(x);
Y = fft(x);
P2 = abs(Y/L);
P1 = P2(1:floor(L/2)+1);
f = Fs*(0:(L/2))/L;
figure(1),clf(1)
plot(f,P1,'-*')
title('Fourrier transform'),xlabel('frequency'),ylabel('magnitude')
Now you can clearly see there are two frequencies that have a high magnitude.
3 Commenti
Più risposte (0)
Vedere anche
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!