View source for Errata: The signal u ff should be u fr in the caption for Figure 11.3 and associated text

{{errata page
| chapter = Frequency Domain Design
| page = 319
| line = 4, -2
| contributor = R. M. Murray
| date = 30 Nov 08
| version = First printing
| text = 
Figure 11.3 uses the notation <amsmath>u_\text{fr}</amsmath> for the output from the feedforward block <math>F_u(s)</math>.  In the caption (line 4) and in the text describing the figure (line -2), the symbol <amsmath>u_\text{ff}</amsmath> should be replaced with <amsmath>u_\text{fr}</amsmath>.
}}