Time scaled version of discrete time signals I have a confusion regarding time scaling of discrete time signals.
Let u[n] be the discrete time unit step signal(or sequence)
Now if i plot u[n/3] i know there will be two zeros added between each previous samples(samples before scaling).
But when i tried plotting the same on MATLAB i got the same plots for u[n] and u[n/3] and even for u[4n].
How could this be?
I am attaching the MATLAB code :
close all;
clear vars;
t=-4:1:20;
stepd=t&gt;=0;
subplot(2,2,1)
stem(t,stepd,'b');
xlabel('n');
ylabel('u[n]');
title('discrete unit step');
stepd1=1/3.*t&gt;=0;
subplot(2,2,2)
stem(t,stepd1,'g');
xlabel('n');
ylabel('u[n/3]');
title('time scaled discrete unit step');
stepd2=4.*t&gt;=0;
subplot(2,2,3)
stem(t,stepd2,'r');
xlabel('n');
ylabel('u[4n]');

I know this is a very silly doubt but please help me come out of this confusion.
I have also attached the plots which i am getting on MATLAB
Now if i plot u[n/3] i know there will be two zeros added between each previous samples(samples before scaling).

No.
You are confusing up-sampling with time scaling. The time scaled version of a unit step is a unit step. You would only insert 2 zeros if you up-sample by a factor of 3.