why I'm getting error with symsum?

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geometry geometry
geometry geometry on 19 Mar 2018
Commented: Walter Roberson on 19 Mar 2018
I have tried this code to calculate energy and power of discrete time functions. but I get errors. how can I fix it?
syms n f z N;
f=input('enter function: ','s');
f = symfun(eval(f), n);
f=f*conj(f);
f = matlabFunction(f);
y(N)=symsum(f, -N , N);
energy=limit(y(N),N,inf);
z(N)=y(N)/(2*N+1);
pow=limit(z(N),N,inf);
  9 Comments
Walter Roberson
Walter Roberson on 19 Mar 2018
You did not use the 'file' option of matlabFunction .
You have
for i=-N:N
but you have not defined N .
Your later line E=limit(E(N),N,inf); would expect N to be sym, but it is not permitted to have a for loop over symbolic range.
Note: you should probably be replacing your heaviside with piecewise, as heaviside has ambiguous meaning at 0.

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