# Code is not working, can someone help me?

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Michael Vaughan on 24 Sep 2020
Commented: Rik on 24 Sep 2020
So I have successfully written scripts for three different functions of 3 variables, Sum1(x,y,z) Sum2(x,y,z) and Sum3(x,y,z)
I have 2 other scripts for functions of just two of these variables: QuantumDimension(x,y) and Twist(x,y)
I'm trying to relate these functions as so:
function c = CJ(x,y,z)
c = (Twist(x,y)^(-2*z)/QuantumDimension(x,y))*(Sum1(x,y,z)+Sum2(x,y,z)-Sum3(x,y,z))
end
So Twist^(-2z) divided by the QuantumDimension, multipled by the sum of the three summations, (Sum1 + Sum2 + Sum3)
This is the output I get when I try to run the code:
Error in CJ (line 2)
c = (Twist(x,y)^(-2*z)/QuantumDimension(x,y))*(Sum1(x,y,z)+Sum2(x,y,z)-Sum3(x,y,z))
I do not see anything wrong with this line!! Insights appreciate, thanks for being patient.

Rik on 24 Sep 2020
How did you define the Sum1 function?
Also note that using sum as a variable name is generally not a good idea, as it will then shadow the built-in function.
Michael Vaughan on 24 Sep 2020
Here is the code for Sum1
function sum = Sum1(x,y,z)
s = 0;
for i=0:min(x,y)
for k=0:x-i
s = s + (-1)^k * QuantumDimension(2*x-2*k-2*i, 2*y+k-2*i) * Twist(2*x-2*k-2*i, 2*y+k-2*i)^(z/2);
end
end
s
The minus sign is indeed intentional
Thanks for the tips! I really appreciate them
Michael Vaughan on 24 Sep 2020
I renamed sum to be s1 and now I get this error message:
Output argument "s1" (and maybe others) not assigned during call to "Sum1".
Error in CJ (line 2)
c = (Twist(x,y)^(-2*z)/QuantumDimension(x,y))*(Sum1(x,y,z)+Sum2(x,y,z)-Sum3(x,y,z))

Rik on 24 Sep 2020
This should fix it:
function s = Sum1(x,y,z)
s = 0;
for i=0:min(x,y)
for k=0:x-i
s = s + (-1)^k * QuantumDimension(2*x-2*k-2*i, 2*y+k-2*i) * Twist(2*x-2*k-2*i, 2*y+k-2*i)^(z/2);
end
end
end

Michael Vaughan on 24 Sep 2020
Thanks man!! Much Appreciated!!
Another question: If I wanted to change CJ(x,y,z) to be a function of two variables whilst keeping z as an indeterminant, how would I have to alter my scripts?? I went through the scripts on Sum1, Sum2, Sum3, QuantumDimension and Twist and added syms z and turned them all into functions of two variables, but that didn't seem to work.
Rik on 24 Sep 2020
What do you mean by that? Do you want to provide z at a later time than x and y? Like a lambda? You can probably get most of the way there with an anonymous function.
Note that I didn't make an attempt to simplify or speed up your code, so the current shape of your functions may not allow you to do what you want.