Plot pole-zero map for I/O pairs with additional plot customization options
iopzplot lets you plot pole-zero maps for input/output pairs
with a broader range of plot customization options than
iopzmap. You can
iopzplot to obtain the plot handle and use it to customize the plot,
such as modify the axes labels, limits and units. You can also use
to draw a pole-zero plot on an existing set of axes represented by an axes handle. To
customize an existing plot using the plot handle:
Obtain the plot handle
getoptionsto obtain the option set
Update the plot using
setoptionsto modify the required options
Change I/O Grouping on Pole/Zero Map
Create a pole/zero map of a two-input, two-output dynamic system.
sys = rss(3,2,2); h = iopzplot(sys);
By default, the plot displays the poles and zeros of each I/O pair on its own axis. Use the plot handle to view all I/Os on a single axis.
Use Pole-Zero Map to Examine Identified Model
View the poles and zeros of a sixth-order state-space model estimated from input-output data. Use the plot handle to display the confidence intervals of the identified model's pole and zero locations.
load iddata1 sys = ssest(z1,6,ssestOptions('focus','simulation')); h = iopzplot(sys); showConfidence(h)
There is at least one pair of complex-conjugate poles whose locations overlap with those of a complex zero, within the 1-σ confidence region. This suggests their redundancy. Hence, a lower (4th) order model might be more robust for the given data.
sys2 = ssest(z1,4,ssestOptions('focus','simulation')); h = iopzplot(sys,sys2); showConfidence(h) legend('6th-order','4th-order') axis([-20, 10 -30 30])
The fourth-order model
sys2 shows less variability in the pole-zero locations.
sys — Dynamic system
dynamic system model | model array
Dynamic system, specified as a SISO or MIMO dynamic system model, or an array of
SISO or MIMO dynamic system models. Dynamic systems that you can use include
continuous-time or discrete-time numeric LTI models such as
tf (Control System Toolbox),
zpk (Control System Toolbox), or
ss (Control System Toolbox) models.
sys is a generalized state-space model
genss or an uncertain state-space model
pzplot returns the poles and transmission zeros of the current or
nominal value of
sys is an array of
pzplot plots the poles and zeros of each model in the array
on the same diagram.
LineSpec — Line style, marker, and color
character vector | string
Line style, marker, and color, specified as a character vector or string containing symbols. The symbols can appear in any order. You do not need to specify all three characteristics (line style, marker, and color). For example, if you omit the line style and specify the marker, then the plot shows only the marker and no line.
'--or' is a red dashed line with circle markers
ax — Axes handle
Axes handle, specified as an axes object. If you do not specify the axes object,
pzplot uses the current axes
gca to plot the
poles and zeros of the system.
h — Pole-zero plot options handle
Pole-zero plot options handle, returned as a scalar. Use
query and modify properties of your pole-zero plot. You can use this handle to customize
the plot with the
Introduced in R2012a