Equation on page 51 seems incorrect

For simplicity, let me refer to

``` tex
\frac{\partial h_{t}}{\partial \underline{h}_{t}}
```

as `D`.

Then, an equation on page 51 says

``` tex
DU = Q (\diag(D) \odot S) Q^{-1}
```

but the LHS is `D Q S Q^{-1}` and the RHS is `Q D S Q^{-1}`, which are not the same.
