I installed FeynCalc 9.0 and then learn it using The FeynCalc Book.
The output on my notebook is different from output of the book.
I do not understand whether it is correct or not.
Would you please help me?Thanks,
the FeynCalc Book is not quite up to date at the moment. Unfortunately, we don't have enough man power to update the documentation simultaneously with the code, see e.g.
The bar is fine. It just signifies that the given object (e.g. Dirac matrix or a 4-vector) lives in 4 dimensions. There was exactly the same question on the mailing list a couple of months ago
so my old answer to that still applies:
Thank you very much.