@atpfm I basically agree that the system settings are so poorly designed that you really have to use search. Unfortunately...
Very funny to me, for some reason, that Wikipedia is using <bra|ket> notation to prove the spectral theorem (which I’m passing through in the context of Linear and ML applications).
It probably makes sense historically, I was just introduced to <bra|ket> as “we use this in quantum but it’s not really what anyone else does.”
(I suppose in retrospect it starts using one-form and tensor rules without having to formally introduce tensors which is probably nice)