Creating Low Pass Filter and Applying

clear all;
close all;
        %frequencies
f1=100;
f2=200;
fc=150; % Low Pass Filter 3db Frequency(Cutoff Frequency)
Fs=1000;%Sampling Frequency
t=0:1/Fs:0.05;% the time domain
f=linspace(-Fs/2,Fs/2,1024);% the frequency domain.

x=2*cos(2*pi*f1.*t)+1.5*sin(2*pi.*f2*t);%our signal
%Parameters to create Low pass filter by ourselves.
i=1;
h=0;
%To create LPF whose cutt off frequency is 150 I use
% for loop and if else statement
% I create the LPF in frequency domain
% LPF is 1 between -150 and 150 and 0 otherwise.
for f3=-500:523
 
    if (f3>=-150)&(f3<=150)
   
      h(i)=1;
         i=i+1;
 
   
    else
       h(i)=0;
    i=i+1;
end
 
end
%Plotting Low Pass Filter h
plot(f,h);


%Xf is representation of signal in frequency domain
%it was defined in time domain
Xf=fft(x,1024);
Xf=fftshift(Xf)/length(x);
% Some of student make a mistake while they
% are normalizing the transferred signal by dividing
%sampling frequency rather than length of signal

% Now We are filtering our signal by Low pass filter(h)
% to do this we are multiplying our signal(Xf) with
%low pass filter.Both of them are  in frequency domain
FilteredX=Xf.*h;
figure(2);
plot(f,(abs(FilteredX)));
subplot(3,1,1);

plot(abs(Xf));
title('Original Signal in Frequency Domain Xf');
subplot(3,1,2);

plot(f,h);
title('Low Pass Filter h');
subplot(3,1,3);

plot(f,(abs(FilteredX)));
title('Filtered Signal by LPF');