MATLAB: Plot discrete time function x(n)=y(n-2). it shows error (Attempted to access y(-1); index must be a positive integer or logical.)

dt plot

clc;
clear all;
x=-5:1:5;
for n=1:11
    if x(n)>=-3&&x(n)<=3
        y(n-2)=2*x(n);
    else
        y(n-2)=0;
    end
end
stem(x,y)
xlabel('n')% x-axis label
ylabel('x(n)')% y-axis label

Best Answer

This error is expected. You are trying to access an index (n-2) even when n is 1 or 2... which MATLAB does not know how to interpret, as vector indices start at 1.
You could add some sort of protection around the edge cases n=1 and n=2 which would cause issues:
if n > 2
  y(n-2) = 2*x(n);
end
This would make y be 2 elements shorter than x, which may or may not be what you want.
- Sebastian
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