Creating and Manipulating Models

Arrays of LTI Models

In many applications, it is useful to consider collections of linear, time invariant (LTI) models. For example, you may want to consider a model with a single parameter that varies, such as

• sys1 = tf(1, [1 1 1]);
  sys2 = tf(1, [1 1 2]);
  sys3 = tf(1, [1 1 3]);
  

and so on. A convenient way to store and analyze a collection like this is to use LTI arrays. Continuing this example, you can create this LTI array and store all three transfer functions in one variable.

• sys_ltia = (sys1, sys2, sys3);
  

You can use the LTI array sys_ltia just like you would use, for example, sys1.

You can use LTI arrays to collect a set of LTI models into a single MATLAB variable. You then use this variable to manipulate or analyze the entire collection of models in a vectorized fashion. You access the individual models in the collection through indexing rather than by individual model names.

LTI arrays extend the concept of single LTI models in a similar way to how multidimensional arrays extend two-dimensional matrices in MATLAB (see Multidimensional Arrays in the MATLAB documentation).

State-Space Realizations

When to Collect a Set of Models in an LTI Array