Dear Oliver, I'll tried to run your code. Instead of Inf for the X2 values I used real values that I increased gradually to check on the influence of this parameter and it seems that beyond 10000 the results remain the same.
I used vpa to convert the symbolic values into numerical ones:
result = vpa (Z_final);
In the images you uploaded we have no information about the coil number of turns and by the way can you give us some information about the origin of the images (book ?)