## ZPLANE Zero-pole plot

Section: Handle-Based Graphics

### Usage

This function makes a zero-pole plot of a discrete-time system defined by its zeros and poles. The various syntaxes arezplane(z,p)

where `z`

and `p`

are the zeros and the poles of the system
stored as column vectors, or

zplane(b,a)

where `a`

and `b`

are the polynomial coefficients of the
numerator and denominator stored as line vectors (`roots`

is
used to find the zeros and poles). The symbol `'o'`

represents
a zero and the symbol `'x'`

represents a pole. The plot includes
the unit circle for reference.
Contributed by Paulo Xavier Candeias under GPL