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pzplot

Pole-zero map of dynamic system model with plot customization options

Syntax

h = pzplot(sys)
pzplot(sys1,sys2,...)
pzplot(AX,...)
pzplot(..., plotoptions)

Description

h = pzplot(sys) computes the poles and (transmission) zeros of the dynamic system model sys and plots them in the complex plane. The poles are plotted as x's and the zeros are plotted as o's. It also returns the plot handle h. You can use this handle to customize the plot with the getoptions and setoptions commands. Type

help pzoptions 

for a list of available plot options. For more information on the ways to change properties of your plots, see Ways to Customize Plots.

pzplot(sys1,sys2,...) shows the poles and zeros of multiple models sys1,sys2,... on a single plot. You can specify distinctive colors for each model, as in

pzplot(sys1,'r',sys2,'y',sys3,'g') 

pzplot(AX,...) plots into the axes with handle AX.

pzplot(..., plotoptions) plots the poles and zeros with the options specified in plotoptions. Type

help pzoptions 

for more detail.

The function sgrid or zgrid can be used to plot lines of constant damping ratio and natural frequency in the s- or z-plane.

For arrays sys of dynamic system models, pzmap plots the poles and zeros of each model in the array on the same diagram.

Examples

collapse all

Plot the poles and zeros of the continuous-time system represented by the following transfer function:

$$sys\left( s \right) = {{2{s^2} + 5s + 1} \over {{s^2} + 3s + 5}}.$$

sys = tf([2 5 1],[1 3 5]);
h = pzplot(sys);
grid on

Turning on the grid displays lines of constant damping ratio (zeta) and lines of constant natural frequency (wn). This system has two real zeros, marked by o on the plot. The system also has a pair of complex poles, marked by x.

Change the color of the plot title. To do so, use the plot handle, h.

p = getoptions(h);
p.Title.Color = [1,0,0];
setoptions(h,p);

Introduced in R2012a

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