Why is my code not working?

Question

Michael Vaughan 2020-9-26

回答： Jim Riggs 2020-9-26

I want the following script to calculate:

$$J_{(2,k)}(N)=\frac{1}{s-s^{-1}}{\sum_{j=\frac{-(N-1)}{2}}^{\frac{(N-1)}{2}}(s^{4j^2k+2jk}s^{4j+1}-s^{4r^2k-2jk}s^{4j-1})}$$

function f = CJ(N,k)

syms t

% compute the running sum

running_sum = 0;

for j = -(N-1)/2:(N-1)/2

running_sum = running_sum + t^(4*j^2*k+2*j*k)*t^(4*j+1)-t^(4*j^2*k-2*j*k)*t^(4*j-1);

end

% final value

f = (1/(t-t^(-1))*running_sum

end

Here is what happens when I try to run the program:

>> CJ(3,2)

Error: File: CJ.m Line: 10 Column: 34

Invalid expression. When calling a function or indexing a variable, use parentheses. Otherwise, check for mismatched

delimiters.

thanks for your help

Answer 1

Jim Riggs 2020-9-26

Not entirely sure if this is the reference in the error message, but this line has unballanced parentheses:

f = (1/(t-t^(-1))*running_sum