View source for Errata: In computation of error dynamics, u ff argument is missing

{{errata page
| chapter = Output Feedback
| page = 220
| line = 12
| contributor = E. Tuna
| date = 13 Feb 08
| rev = 2.9d
| version = First printing
| text = 
In the derivation of the error dynamics, the underlined term is missing:
<center><amsmath>
  \aligned 
    \dot z &= \dot x - \dot x_d = f(x, u) - f(x_d, u_\text{ff}) \\
           &= f(z + x_d, v + u_\text{ff}) - f(x_d, \underline{u_\text{ff}}) 
           =: F (z, v, x_d(t), u_\text{ff}(t)).
  \endaligned
</amsmath></center>
}}