Specifications

size
16-202
16size
Purpose Provide the output/input/array dimensions of LTI models, the model order of
TF, SS, and ZPK models, and the number of frequencies of FRD models
Syntax size(sys)
d = size(sys)
Ny = size(sys,1)
Nu = size(sys,2)
Sk = size(sys,2+k)
Ns = size(sys,'order')
Nf = size(sys,'frequency')
Description When invoked without output arguments, size(sys) returns a vector of the
number of outputs and inputs for a single LTI model. The lengths of the array
dimensionsare also included in theresponse to
size when sys is an LTI array.
size is the overloaded version of the MATLAB function size for LTI objects.
d = size(sys) returns:
• The row vector
d = [Ny Nu] for a single LTI model sys with Ny outputs and
Nu inputs
• The row vector
d = [Ny Nu S1 S2 ... Sp] for an S1-by-S2-by-...-by-Sp array
of LTI models with
Ny outputs and Nu inputs
Ny = size(sys,1) returns the number of outputs of sys.
Nu = size(sys,2) returns the number of inputs of sys.
Sk = size(sys,2+k) returns the length of the k-th array dimension when sys
is an LTI array.
Ns = size(sys,'order') returns the model order of a TF, SS, or ZPK model. This
is the same as the number of states for state-space models. When
sys is an LTI
array, ns is the maximum order of all of the models in the LTI array.
Nf = size(sys,'frequency') returns the number of frequencies when sys is
an FRD. This is the same as the length of
sys.frequency.
Example Consider the random LTI array of state-space models
sys = rss(5,3,2,3);
Its dimensions are obtained by typing