Equation on the top of page 49 is incorrect

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)
