k=0:63;
f=sin((pi/8)*k)+2*cos((7*pi/8)*k);
F=fft(f);
plot(abs(F),'k-*');  
title('Original Power Spectrum');

keyboard

g=f+0.2*randn(size(f));
F=fft(g);
plot(abs(F),'k-*');
title('Noisy Power Spectrum');

keyboard

[vals,idx]=find(abs(F)<10);
Fnew=F;
Fnew(idx)=zeros(size(idx));
g1=ifft(Fnew);
g1=real(g1);

plot(0:63,f,0:63,g,0:63,g1);
legend('Original','Noisy','Cleaned');