National Instruments NI MATRIXx Xmath - Manual (Page 115)

Chapter 6 Tutorial
Xmath Model Reduction Module 6-20 ni.com
fracred
fracred , the next command examined, has four options— "right
stab" , "left stab" , "right perf" , and "left perf" .
The options "left stab" , "right perf" , and "left perf" all
produce instability. Given the relative magnitudes of the Hankel singular
values, this is perhaps not surprising. Figures 6-16, 6-17, and 6-18
illustrate the results using
"right stab" .
Generate Figure 6-16:
svalsrol = svplot(sys*syscr,w,{radians})
plot(svalsol, {keep})
f16=plot(wc,constr,{keep,!grid,
legend=["reduced","original","constrained"],
title="Open-Loop Gain Using fracred()"})
Figure 6-16. Open-Loop Gain Using fracred