I continue to think this is at least one bug. There is an easy fix via change_ring():
sage: M=F.adjacency_matrix();f=M.characteristic_polynomial();f=f.change_ring(AA) ....: ;ro=f.roots();sum(e for _,e in ro) 90 -- You received this message because you are subscribed to the Google Groups "sage-devel" group. To unsubscribe from this group and stop receiving emails from it, send an email to sage-devel+unsubscr...@googlegroups.com. To view this discussion visit https://groups.google.com/d/msgid/sage-devel/CAGUWgD8PyrLa%2BKe5rryTzs-htn9gPJbKCFaFUpaS%2B7k%3DJiZqAw%40mail.gmail.com.
