[hz,hp,ht] = zplane(z,p)
This function displays the poles and zeros of discrete-time systems.
zplane(z,p) plots the zeros
specified in column vector
z and the poles specified
in column vector
p in the current figure window.
'o' represents a zero and the symbol
a pole. The plot includes the unit circle for reference. If
zplane plots the poles and zeros in the
p in different
row vectors, first uses
find the zeros and poles of the transfer function represented by numerator
b and denominator coefficients
The transfer function is defined in terms of z–1:
zplane(d) finds the zeros
and poles of the transfer function represented by the digital filter,
designfilt to generate
on frequency-response specifications. The pole-zero plot is displayed
[hz,hp,ht] = zplane(z,p) returns
vectors of handles to the zero lines,
hz, and the
ht is a vector
of handles to the axes/unit circle line and to text objects, which
are present when there are multiple zeros or poles. If there are no
zeros or no poles,
the empty matrix
For data sampled at 1000 Hz, plot the poles and zeros of a 4th-order elliptic lowpass digital filter with cutoff frequency 200 Hz, 3 dB of ripple in the passband, and 30 dB of attenuation in the stopband.
[z,p,k] = ellip(4,3,30,200/500); zplane(z,p) grid title('4th-Order Elliptic Lowpass Digital Filter')
Create the same filter using
fvtool to plot its poles and zeros.
d = designfilt('lowpassiir','FilterOrder',4,'PassbandFrequency',200, ... 'PassbandRipple',3,'StopbandAttenuation',30, ... 'DesignMethod','ellip','SampleRate',1000); zplane(d)