78 CHAPTER 3. FUNCTIONAL DESCRIPTION OF Xµ
# Select columns 1, 3,4&5androws 2 & 7 from the
# pdm: bigpdm.
subpdm = bigpdm([1,3:5],[2,7])
This referencing formatcan also be usedto assign data to parts of a larger pdm. This is
shown in the following example.
# Replace the 3,2 block of a pdm with its absolute value
pdm1(3,2) = abs(pdm1(3,2))
When selecting subblocks of a Dynamic System or pdm, the appropriate original labels
(input, output and state; row, column and domain) are appended to the subblock.
3.2.4 Basic Functions
In all Xµfunctions which operator on Dynamic Systems a matrix input is interpreted
as a system with constant gain: the equivalent of system([],[],[],mat). This
interpretation also applies to binary operations between Dynamic Systemsand
matrices in both Xmath and Xµ. For example, +,*,daug,....
In binary operations between pdms and matrices, the matrix is assumed to have a
constant value at each elemento f the domain of the pdm. Again, this is consistent with
the interpretation of a matrix as a system with no dynamics.
Note that this interpretation works for Xµand the basic Xmath operations; it will not
necessarily apply to other Xmath modules or more sophisticated Xmath functions.
Augmentation
Augmentation is the building of matrices from component pieces. Dynamic Systems
and pdms can be augmented with the same syntax as matrices. Data objects can be
augmented, side by side, with the command [A, B]. Similarly,[A; B], places Aabove B.
In Dynamic Systems[A, B] is analogous to summing the outputs of the systems A
and B.[A; B] is analogous to creating a larger system where the input goes to both A