t=0:0.02:10;
Fs=50;
x1=sin(2*pi*t*2);
x2=0.5*sin(2*pi*t*5);
x3=0.5*exp(1-(t-1.5).^2/2*0.5*0.5);
x=x1+x2+x3;
XT=fftshift(fft(x));
f=linspace(-Fs/2,Fs/2,length(t));
WA=abs(XT);
plot(f,WA);
LP=1./(1+((f.*0.5)./(f.*f-2*2)).^10);
new_x=ifft(ifftshift(XT.*LP));
subplot(211), plot(t,x);
subplot(212), plot(t,new_x);