shift to left sequence

hi. i want to shift my sequence to left but there is a problem.

clc;
clear all;
close all;

% our domain in 11
n  = 0:10;
x  = cos (n*pi/12);

% shift x to left 2 unit 
x2 = [x 0 0];
y  = 2*x;
y2 = 2*x2;

d  = y - y(-2:11-2);
% do should be = 0
stem (n,y2)

the problem is i can't enter a negative value to y(-2:9);

how can i change that line?

-------------------------------------------------------

errore:

Array indices must be positive integers or logical values.

Error in Untitled (line 14)

d = y - y(-2:11-2);

[David Hill]

I have no idea what you want to do. Please provide and example. [1 2 3 4] goes to what?

Answer 1

[Ameer Hamza]

Read about circshift(): https://www.mathworks.com/help/matlab/ref/circshift.html

n  = 0:10;
x  = cos (n*pi/12);

y = circshift(x, 2)

[Stephen23]

HADIMARGO's "Answer" moved here:

thank you Mr. Ameer. But i don't want to use this function.

i want to shift with this structure :

x2 = [ x 0 0];

[HADIMARGO]

also this is not my main problem.

my main problem is how to use y(-2:11-2); with that error.

[Ameer Hamza]

Negative indexes are not supported in MATLAB like they do in python. MATLAB supports something like the following if that helps

n  = 0:10;
x  = cos (n*pi/12);
y = x([end-1:end 1:end-2])