Creating and Manipulating Models

Accessing Particular Models in an LTI Array

To access any given model in an LTI array:

• Use colon arguments (:,:) for the first two indices to select all I/O channels.
• The remaining indices specify the model coordinates within the array.

For example, if sys is a 5-by-2 array of state-space models defined by

• sys = rss(4,3,2,5,2);
  

you can access (and display) the model located in the (3,2) position of the array sys by typing

• sys(:,:,3,2)
  

If sys is a 5-by-2 array of 3-output, 2-input FRD models, with frequency vector [1,2,3,4,5], then you can access the response data corresponding to the middle frequency (3 rad/s), of the model in the (3,1) position by typing

• sys(:,:,3,1,'frequency',3.0)
  

To access all frequencies of this model in the array, you can simply type

• sys(:,:,3,1)
  

Single Index Referencing of Array Dimensions

You can also access models using single index referencing of the array dimensions.

For example, in the 5-by-2 LTI array sys above, you can also access the model located in the (3,2) position by typing

• sys(:,:,8)
  

since this model is in the eighth position if you were to list the 10 models in the array by successively scanning through its entries along each of its columns.

For more information on single index referencing, see Advanced Indexing under "M-File Programming" in the MATLAB online documentation.

Indexing Into LTI Arrays

Extracting LTI Arrays of Subsystems