Circular Convolution Method 2

Matlab program to find Circular Convolution by matrix multiplication using circshift command.

Two another methods of Circular Convolution:  Using fft and ifft predefined function and By using for loop function.

Matlab code

clc;close all; clear all;

x1=input('Enter the 1st sequence x[n] = ');
h1=input('Enter the 2nd sequence h[n] = ');
N1=length(x1);

N2=length(h1);

N=max(N1,N2);%Length of Circular convolved output sequence

if(N1>N2)

h1=[h1,zeros(1,N1-N2)]; %Modified second sequence if N1>N2

else

x1=[x1,zeros(1,N2-N1)]; %Modified first sequence if N1

end;

x=transpose(x1); h=transpose(h1); temp=h;

for i=1:N-1;
  temp=circshift(temp,1);
  h=horzcat(h,temp);

end;

h
x

y=h*x ;

disp('Circular convolved output y[n] = ');y %To view output in command window

%To display and plot circular convolution

subplot(3,1,1);

stem(x1); xlabel('N-->');

ylabel('Amplitude-->'); title('1st input sequence x[n] ');

subplot(3,1,2);

stem(h1); xlabel('N-->');

ylabel('Amplitude-->'); title('2nd input sequence h[n]');

subplot(3,1,3);

stem(y); xlabel('N-->');

ylabel('Amplitude-->');

title('Circular convolved output y[n]');

Command window

Enter the 1st sequence x[n] = [1 2 3 4]

Enter the 2nd sequence h[n] = [3 5 2 1]

h =

     3     1     2     5

     5     3     1     2

     2     5     3     1

     1     2     5     3

x =

     1

     2

     3

     4

Circular convolved output y[n] = 

y =

    31

    22

    25

    32

Figure window