Inverse Z Transform recursion code not working?

So I was working on this code that basically uses the power series to use recursion to do an inverse Z transform from a given function. ~

syms a b i n x z % Create symbolic variables

prompt = 'What is the value of n? ';
x_n = input(prompt)
x_n = (a*n - symsum(x*(n-i))*b*i/b);
x_n=simplify(x_n)       
g=iztrans(x_n,z,n);   %Inverse Z-transform for xn[z]
g=simplify(g)       
Fs = 100;           % Sampling frequency
T = (1 / Fs)*pi;    % Sampling period (time interval between samples)
L = 10*pi;          % Length of signal duration in seconds
t= (0:T:(L-T));     % Time interval set
g=subs(g,n,t);          %Substitute the values of t into the double value h
figure(1);                         % Open a new figure
stem(t,g)             % Plot the transfer function 
                                                    
hold on 
h2=sin(pi.*t/3);    
stem(t,(h2))
hold off
xlabel('t / s');                
ylabel('h(t)');

However, when running the code, it outputted this:

Answer 1

[Shadaab Siddiqie]

From my understanding you are getting an error for the above code. This is because you are substituting the n with t, in line

g=subs(g,n,t);          %Substitute the values of t into the double value h

but still g here has another variable x which is not assigned to any value before your plot it in line

stem(t,g)             % Plot the transfer function 

therefore, you are getting an error. Please refer syms and subs for more information.