Here is the code i have written .
Number of samples= 50000 samples.
fs=50000000; %Sampling frequency
nfft=length(m);
%nfft=2^nextpow2(nfft);
X=fft(m,nfft); %FFT of the signal
X=X(1:nfft/2);
%take magniutde
mx=abs(X);
f=(0:(nfft/2)-1)*fs/nfft; %Frequency range
figure(1);
n=50000;
t=0:1:(n-1);
plot(t,m);
title('Multisine')
xlabel('Samples')
ylabel('Amplitude');
figure(2)
plot(f,mx);
title('FFT of signal')
xlabel('Frequency')
ylabel('Amplitude');
