Thanks a lot I read about locals and individual dictionaries, but I didn't realize that it would affect "already defined" Symbols. It is a little bit confusing that 'a' and 'a' can be not the same thing.
But now everything works as expected, thanks again. -- You received this message because you are subscribed to the Google Groups "sympy" group. To unsubscribe from this group and stop receiving emails from it, send an email to sympy+unsubscr...@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/sympy/5d9325aa-6eb4-4340-af0d-5e0f3a93c419%40googlegroups.com.