The RHS ``` tex \diag(S^{l-t'}) \odot (Q Q^{-1} W\phi(x_{t'})) ``` is equivalent to ``` tex S^{l-t'} Q Q^{-1} W\phi(x_{t'}) ``` which is not the same thing as ``` tex Q S^{l-t'} Q^{-1} W\phi(x_{t'}) ``` (which is the LHS)
The RHS
is equivalent to
S^{l-t'} Q Q^{-1} W\phi(x_{t'})which is not the same thing as
Q S^{l-t'} Q^{-1} W\phi(x_{t'})(which is the LHS)