Zero-pole plot for discrete-time systems

`zplane(`

plots the zeros specified in column vector `z`

,`p`

)`z`

and the poles
specified in column vector `p`

in the current figure window.
The symbol `'o'`

represents a zero and the symbol
`'x'`

represents a pole. The plot includes the unit circle
for reference.

If `z`

and `p`

are matrices, then
`zplane`

plots the poles and zeros in the columns of
`z`

and `p`

in different
colors.

`zplane(`

finds the zeros and poles
of the transfer function represented by the digital filter,
`d`

)`d`

. Use `designfilt`

to generate
`d`

based on frequency-response specifications. The
pole-zero plot is displayed in **FVTool**.

You can override the automatic scaling of

`zplane`

usingaxis([xmin xmax ymin ymax])

after calling

`zplane`

. This scaling is useful when one or more zeros or poles have such a large magnitude that the others are grouped tightly around the origin and are hard to distinguish.