clc
close all
clear all

%Ejercicio 1
n = -10:20;
x = heaviside(n-5)-heaviside(n+6);
X = fft(x);
stem(n,x), axis([-10 20 -2 2])
figure, plot(abs(X))

%Ejercicio 2
a = 1;    % a > 0
xa = exp(-a*n).*heaviside(n);
subplot(1,2,1), stem(n,xa)
Xa = fft(xa);
subplot(1,2,2), plot(abs(Xa)), title('exp(-a*n)*u[n]')
%%%%%%%%%%%%%%%%%%%%%%%%%
xb = (0.5).^(n-1).*heaviside(n-1);
figure,subplot(1,2,1), stem(n,xb)
Xb = fft(xb);
subplot(1,2,2), plot(abs(Xb)), title('0,5^(n-1)*u[n-1]')

%Ejercicio 3
figure, subplot(3,2,1), plot(real(X))
subplot(3,2,2), plot(imag(X))
subplot(3,2,3), plot(real(Xa))
subplot(3,2,4), plot(imag(Xa))
subplot(3,2,5), plot(real(Xb))
subplot(3,2,6), plot(imag(Xb))

figure, subplot(3,2,1), plot(abs(X))
subplot(3,2,2), plot(angle(X))
subplot(3,2,3), plot(abs(Xa))
subplot(3,2,4), plot(angle(Xa))
subplot(3,2,5), plot(abs(Xb))
subplot(3,2,6), plot(angle(Xb))