Specifications

zpkdata
16-237
16zpkdata
Purpose Quick access to zero-pole-gain data
Syntax [z,p,k] = zpkdata(sys)
[z,p,k] = zpkdata(sys,'v')
[z,p,k,Ts,Td] = zpkdata(sys)
Description [z,p,k] = zpkdata(sys) returns thezerosz,polesp,andgain(s)k ofthe zero-
pole-gain model
sys.Theoutputsz and p are cell arrays with the following
characteristics:
•
z and p have as many rows as outputs and as many columns as inputs.
• The
(i,j) entries z{i,j} and p{i,j} are the (column) vectors of zeros and
poles of the transfer function from input
j to output i.
The output
k is a matrix with as many rows as outputs and as many columns
as inputs such that
k(i,j) is the gain of the transfer function from input j to
output
i.Ifsys is a transfer function or state-space model, it is first converted
to zero-pole-gain form using
zpk. See Table 11-15, “LTI Properties,” on page
11-194 for more information on the format of state-space model data.
For SISO zero-pole-gain models, the syntax
[z,p,k] = zpkdata(sys,'v')
forces zpkdata to return the zeros and poles directly as column vectors rather
than as cell arrays (see example below).
[z,p,k,Ts,Td] = zpkdata(sys) also returns the sample time Ts and the
input delay data
Td. For continuous-time models, Td is a row vector with one
entry per input channel (
Td(j) indicates by how many secondsthe jth input is
delayed). For discrete-time models,
Td is the empty matrix [] (see d2d for
delays in discrete systems).
You can access the remaining LTI properties of
sys with get or by direct
referencing, for example,
sys.Ts
sys.inputname
Example Given a zero-pole-gain model with two outputs and one input
H = zpk({[0];[-0.5]},{[0.3];[0.1+i 0.1-i]},[1;2],-1)