close all
clear all 
clc

x = [-1,3,-5,2];
nx = -1:2;
g = [1,2,-1];
ng = 0:2;
y = conv(x,g);
ny = [nx(1)+ng(1):nx(end)+ng(end)];

figure
subplot(2,2,1)
stem(nx,x)
grid
xlabel('n')
ylabel('x(n)')
subplot(2,2,2)
stem(ng,g)
grid
xlabel('n')
ylabel('g(n)')
subplot(2,1,2)
stem(ny,y)
grid
xlabel('n')
ylabel('y(n)=x*g(n)')
sgtitle('discrete-time convolution')

% printing figure in png format
set(gcf,'PaperUnits','inches','PaperPosition',[0 0 4 3])
print -dpng exercise1.png -r100