Let Amn be a matrix representation of some operator A in the basis |φn> and let Unj be a unitary operator that changes the basis |φn> to a new basis |ψj>. I am asked to write down the matrix representation of A in the new basis.
The Attempt at a Solution
Should I try to evaluate <m|UnjA|n>? Is that how this should be approached?
I know that Unj|φn>=|ψj>.