Why does LTIVIEW treat an input array of systems as a single system in Control System Toolbox (R2013a)?

Consider the code below:

sys1 = rss(3,2,2);

sys2 = rss(4,2,2);

sys = [sys1 sys2];

ltiview(sys);

There will be as many panes in one viewer as there are elements in the vector. The customer would like to have only one pane used for all the systems so that the curves are all superimposed in the same pane.

Answer 1

[MathWorks Support Team]

A concatenation of two systems results in a new system altogether whose number of inputs and output is the sum of the inputs and outputs of the two original systems, rather than producing an array of two systems. Due to this, the LTI Viewer treats the input as a single system and generates as many panes as there are inputs and outputs.

The only way to super-impose plots for multiple systems is to input them in a comma separated manner as shown in the Documentation:

ltiview(sys1, sys2,...,sysN);

In case we need to view an already stacked system as multiple systems in the LTI Viewer, we have to manually concatenate a string containing each system's representation by indexing the array, to obtain a final string of the form (where N is variable):

ltiview(sys1, sys2,...,sysN)

and then perform an EVAL on the final string.