semantic error log function

[mcgrim]

I guarantee you that the first time xx shows is when I set it to a0.
However I am trying to make a0 a list, so if you are aware of a way to do that
without using xx, please share, as I have tried before but I got a float object error
(see previous comments).

In order for you to have a better Idea of what I am trying to do,
I will write again the iteration formulas I am trying to accomplish
with this code:

the first 6 lines of my code are totally correct, and the code right after is based on it.

Now we have cc_sub(0,i)=a0
cc_sub(k,i)=( cc_sub(k-1,i)-4^(-k)*cc_sub(k-1,i-1) )/(1 - 4^(-k))

I want cc to be dependent on line 5-6 and not 3-4.
I transformed a0 into a list because the new a0 (cc) has two iteration characters (k,i)
as you can see from the formula.

we can forget about xx and not use it at all if is easier for you to explain without
this variable, but please let me know how my code should change in order to accomplish the
iteration above written.
(again, the first 6 lines should be left untouched, because they are correct)

Let me please know if there is any further clarification you want to request.