clear
close all
clc


% Convolution function
function [ Y ] = convolution( h, x )
    Ny = length(x)+length(h)-1
    Y = zeros(1, Ny);
    for n = 1:Ny
        for i = 1:length(h)
            if (n-i+1 >= 1) && (n-i+1 <= length(x))
                Y(n) = Y(n) + h(i) * x(n-i+1)
            end
        end
    end
end

n = 0:49
hn = [0.25, 0.5, 0.25]
xn = cos(((2*pi)/20)*n)

% Perform convolution of xn and hn
Y = convolution(hn, xn);
Y2 = conv(xn, hn)

% Plot the results
plot(Y);
xlabel('Sample Index');
ylabel('Amplitude');
title('Convolution Result');
grid on;

% Plot Y2 on same graph
hold on;
plot(Y2, '--');
legend('Custom Convolution', 'MATLAB conv Function');
hold off;