EEG frequence and noise estemation

Hello

I have noised EEG signal stored in this txt file.

I need to get the estimated frequency for the signal and the noise frequency

I am trying this code bellow

x=load('5.txt'); 
y = fft(x); 
PS = abs(y).^2; 
N = length(x); 
fs = 500;
freq = (1:N/2)*fs/N;
plot(freq,PS);

but I got error:

Error using plot
Vectors must be the same length.
Error in untitled (line 7)
plot(freq,PS); 

Thanks

Answer 1

[chicken vector]

Look at fft documentation:

x=load('5.txt'); 
y = fft(x); 
PS = abs(y).^2; 
N = length(x); 
fs = 500;

% From documentation:
L = length(x);
P2 = abs(Y/L);
freq = P2(1:L/2+1);
freq(2:end-1) = 2*freq(2:end-1);

plot(freq,PS);