User`s guide

pade
11-166
Example Compute a third-order Padé approximation of a 0.1 second I/O delay and
compare the time and frequency responses of the true delay and its
approximation. To do this, type
pade(0.1,3)
Limitations High-order Padé approximations produce transfer functions with clustered
poles.Becausesuchpoleconfigurationstendtobeverysensitiveto
perturbations, Padé approximations with order
N>10 should be avoided.
See Also c2d Discretization of continuous system
delay2z Changestransferfunctionsof discrete-timeLTImodels
with delays torationalfunctionsorabsorbsFRDdelays
into the frequency response phase information
0 0.02 0.04 0.06 0.08 0.1 0.12 0.14 0.16 0.18 0.2
−1
−0.5
0
0.5
1
1.5
Time (secs)
Amplitude
Step response of 3rd−order Pade approximation
10
1
10
2
10
3
−1000
−800
−600
−400
−200
0
Frequency (rad/s)
Phase (deg.)
Phase response