in this video you will find a code on matlab about up sampling
clc
clear all
n=0:49
x=sin(2*pi*0.12*n)
y=zeros(1,3*length(x))
y([1:3:length(y)])=x
subplot(2,1,1)
stem(n,x)
title ('input sequence')
xlabel('time index n')
ylabel('Amplitude')
subplot(2,1,2)
stem(n,y(1:length(x)))
title ('output sequence')
xlabel('time index n')
ylabel('Amplitude')
