<1번 코드> 


t = data(:,1);
x = data(:,2);

Maxnumber=max(size(t));
dt=0.002;
N=fix(log10(Maxnumber)/log10(2));
xfft=fft(x(1:2^N));
xfft=abs(xfft(1:2^N/2))*dt;
Af=(1/dt)/2;
df=Af/(2^N/2);
A=0:df:Af-df;
plot(A,xfft)
xlabel(\'frequency\')
ylabel(\'Magnitude\')
grid on




<2번 코드>


Fs = 500;                  
T = 1/Fs;                    
L = 2000;                     
t = (0:L-1)*T;                
x = data(:,2); 
y = x;    
plot(Fs*t,y)
title(\'Signal Corrupted with Zero-Mean Random Noise\')
xlabel(\'time (milliseconds)\')

NFFT = 2^nextpow2(L); % Next power of 2 from length of y
Y = fft(y,NFFT)/L;
f = Fs/2*linspace(0,1,NFFT/2+1);

plot(f,2*abs(Y(1:NFFT/2+1))) 
title(\'FFT\')
xlabel(\'Frequency (Hz)\')
ylabel(\'Magnitude\')

grid on




<3번 코드> 



x=data(:,2);
N = 2000; 
Fs= 500; 
xdft = fft(x-mean(x))/N;
xdft = xdft(1:length(x)/2+1);

freq = linspace(0,Fs/2,length(x)/2+1);
plot(freq,2*abs(xdft));
xlabel(\'Hz\'); ylabel(\'Magnitude\');
grid on




----------------------------------



로드함수는 다 되있다생각하고 

뭐가 맞는거죠 1번이 젤 다르긴한데

From 영원정 ✨