Create Index variable name for entering n variables names

I am solving highly non linear PDE system (2 variables 2 equations) (variables are Pg and Sg)

I applied finite difference--this gives variables with names like Pg(I+1), Pg(I-1), Pg(I) , Sg(I+1), Sg(I), Sg(I-1)

Now if you take 4 nodes this makes 8 variables (4 Pg and 4 Sg ) variables

Now since my equations are non linear, I have to apply newton Raphson method for system of equations

Now each Node eqn is treated as a non linear function, and evaluated at initial values

I cant write each equation; not possible using syms as : syms Sg1 Sg2 Sg3 Sg4 Pg1 Pg2 Pg3 Pg4 can help in solving 4 nodes but itss not possible when I use 100 nodes

I need an indexing way to create symbolic names syms Sg(I) AND ITERATE THEM FROM 1: 100 BUIT ITS NOT WORKING???

PLEASE HELP...SOMEONE...