# Hello I'm getting this warning "Variable 'x1' might be set by a nonscaler operator".

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AlireaA Mirrabie on 20 Sep 2022
Commented: AlireaA Mirrabie on 22 Sep 2022
This is a exercise to write a piece of code which would determine and plot the odd and even parts of a discontinuous time signal. It's not my code I just copied it from youtube. I would like to know why this code works just fine with continuous time signals and how can I rewrite the code to avoid this issue.
close; clear; clc;
n = -5:5;
A = 0.8;
x1 = A.^n;
x2 = A.^(-n);
if (x1 == x2)
disp('"The given signal is even!"')
elseif (x1 == (-x2))
disp('"the given signal is odd!"')
else
disp('"The given signal in nither odd nor even!"')
end
"The given signal in nither odd nor even!"
xe = ( x1 + x2 )/2;
xo = ( x1 - x2 )/2;
tiledlayout(2,2); nexttile;
stem(n,x1);
xlabel("n");
ylabel("x1(n)");
title("signal x(n)")
nexttile;
stem(n,x2);
xlabel("n");
ylabel("x2(n)");
title("signal x(-n)")
nexttile;
stem(n,xe);
xlabel("n");
ylabel("xe(n)");
title("Even Part of x(n)")
nexttile;
stem(n,xo);
xlabel("n");
ylabel("xo(n)");
title("Odd Part of x(n)")

Chunru on 20 Sep 2022
close; clear; clc;
n = -5:5;
A = 0.8;
x1 = A.^n;
x2 = A.^(-n);
if all(x1 == x2) % use all here to ensure all elements of x1 and x2 are same
disp('"The given signal is even!"')
elseif all(x1 == (-x2))
disp('"the given signal is odd!"')
else
disp('"The given signal in nither odd nor even!"')
end
"The given signal in nither odd nor even!"
xe = ( x1 + x2 )/2;
xo = ( x1 - x2 )/2;
tiledlayout(2,2); nexttile;
stem(n,x1);
xlabel("n");
ylabel("x1(n)");
title("signal x(n)")
nexttile;
stem(n,x2);
xlabel("n");
ylabel("x2(n)");
title("signal x(-n)")
nexttile;
stem(n,xe);
xlabel("n");
ylabel("xe(n)");
title("Even Part of x(n)")
nexttile;
stem(n,xo);
xlabel("n");
ylabel("xo(n)");
title("Odd Part of x(n)")
AlireaA Mirrabie on 22 Sep 2022

KSSV on 20 Sep 2022
You case x1, x2 are vectors and you cannot use the condition like that.
You have to use like shown below.
n = -5:5;
A = 0.8;
x1 = A.^n;
x2 = A.^(-n);
idx = x1 == x2 ;
[x1(idx)' x2(idx)']
[x1(~idx)' x2(~idx)']