User`s guide

3 Operations on LTI Models
3-6
Note:
•
sys, the LTI model that has had a portion reassigned, retains its original
model type (TF, ZPK, SS, or FRD) regardless of the model type of
NewSubSys.
• If
NewSubSys is an FRD model, then sys must also be an FRD model.
Furthermore, their frequencies must match.
• Subsystem assignment does not reassign any I/O names or I/O group names
of
NewSubSys that are already assigned to NewSubSys.
• Reassig n ing parts of a MIMO state-space model general ly increases its
order.
Other sta ndard matrix subindexing extends to LTI objects as well. For
exampl e,
sys(3,1:2)
extracts the subsystem mapping the first two inputs to the third output.
sys(:,1)
selects the first input and all outputs, a nd
sys([1 3],:)
extractsa subsystemwith the sameinputs, but only thefirst and third outputs.
For example, consider the two-input/two-output transfer function
.Ts()
1
s 0.1+
-----------------
0
s 1–
s
2
2 s 2++
----------------------------
1
s
---
=