clear
close all
clc

% x1[n], -5 <= n <= 10
n1 = -5:10;
x1 = -4*(n1 == -3) + 4*(n1 == 0) - (n1 == 3) + 2*(n1 == 7);

% x2[n], -5 <= n <= 10
n2 = -5:10;
x2 = exp(-0.31*n2);

% x3[n], 0 <= n <= 256
n3 = 0:256;
x3 = 3*sin(2*pi*(3.5/64)*n3);

% x4[n], 0 <= n <= 256
n4 = 0:256;
x4 = -cos((9/64)*n4);


% Visualization
figure;
subplot(121); hold on; grid on;
stem(n1, x1);
stem(n2, x2);
xlabel('n');
ylabel('x[n]');
legend('x_1[n]', 'x_2[n]');

subplot(122); hold on; grid on;
plot(n3, x3);
plot(n4, x4);
xlabel('n');
ylabel('x[n]');
legend('x_3[n]', 'x_4[n]');

% Custom power function
function [ P ] = custom_power( x )
    P = (1/length(x)) * sum(abs(x).^2);
end

% Calculate and display the power
P3 = custom_power(x3);
% Display the calculated powers
disp(['Power of x_3[n]: ', num2str(P3)]);

% Energy function
function [ W ] = energy( x )
    W = sum(abs(x).^2);
end

% Calculate and display the energy of each signal
P1 = energy(x1);
P2 = energy(x2);
P3 = energy(x3);
P4 = energy(x4);
% Display the calculated powers
disp(['Energy of x_1[n]: ', num2str(P1)]);
disp(['Energy of x_2[n]: ', num2str(P2)]);
disp(['Energy of x_3[n]: ', num2str(P3)]);
disp(['Energy of x_4[n]: ', num2str(P4)]);