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recovery at low frequencies; there is consequently a faster roll-off of the 
loop gain at high frequencies than for 

, and this is desired. 

Figure 6-2 displays the (magnitudes of the) plant transfer function, the 
compensator transfer function and the loop gain, as well as the constraints; 
evidently the compensated plant meets the constraints.

You can enter the following commands to create a plot equivalent to 
Figure 6-2:

sysol=sys*sysc;

svals=svplot(sys,w,{radians});

svalsc=svplot(sysc,w,{radians});

svalsol=svplot(sysol,w,{radians});

plot(svals,{x_log,!grid,!ylab,

line_width=2,hold})

plot(svalsc,{keep})

plot(svalsol,{keep})

f2=plot(wc,constr,{keep,

legend=["plant","compensator",

"compensated plant","constraint"]})

plot({!hold})

Figure 6-2.  Frequency Response for Plant, Compensator, and Compensated Plant

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