Specifications

2 LTI Models
2-52
sys.iodelay
get(sys,'inputdelay')
•Use the helper function hasdelay to determine if sys has any delay at all.
The syntax is
hasdelay(sys)
which returns 1 (true) if sys has any delay, and 0 (false) otherwise
•Usethefunction
totaldelay todeterminethetotaldelaybetweeneachinput
and each output (cumulative contribution of the
ioDelay, InputDelay,and
OutputDelay properties). Type help totaldelay or see the Reference pages
for details.
Padé Approximation of Time Delays
The function pade computes rational approximations of time delays in
continuous-time LTI models. The syntax is
sysx = pade(sys,n)
where sys is a continuous-time model with delays, and the integer n specifies
the Padé approximation order. The resulting LTI model
sysx is of the same
type as
sys, but is delay free.
For models with multiple delays or a mix of input, output, and I/O delays, you
can use the syntax
sysx = pade(sys,ni,no,nio)
where the vectors ni and no,andthematrixnio specify independent
approximation orders for each input, output, and I/O delay, respectively. Set
ni=[] if there are no input delays, and similarly for no and nio.
For example, consider the “Distillation Column Example” on page 2-45. The
two-input, two-output transfer function in this example is
Hs()
12.8e
1s–
16.7e 1+
------------------------
18.9e
3s–
–
21.0s 1+
-------------------------
6.6e
7s–
10.9s 1+
------------------------
19.4e
3s–
–
14.4s 1+
-------------------------
=