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Generate z-plane grid of constant damping factors and natural frequencies

`zgrid`

generates a grid of constant damping factors from 0 to 1 in
steps of 0.1 and natural frequencies from 0 to `π/T`

in steps of
`0.1*π/T`

for root locus and pole-zero maps. The default steps of
`0.1*π/T`

represent fractions of the Nyquist frequencies.
`zgrid`

then plots the grid over the current axis.
`zgrid`

creates the grid over the plot without altering the current
axis limits if the current axis contains a discrete z-plane root locus diagram or
pole-zero map. Use this syntax to plot multiple systems with different sample
times.

Alternatively, you can select **Grid** from the context
menu in the plot window to generate the same z-plane grid.

`zgrid(`

generates the z-plane grid by using
default values for damping factor and natural frequency relative to the sample time
`T`

)`T`

.

`zgrid(`

plots a
grid of constant damping factor and natural frequency lines for the damping factors and
normalized natural frequencies in the vectors `zeta`

,`wn`

)`zeta`

and
`wn`

, respectively. When the sample time is not specified, the
frequency values in `wn`

are interpreted as normalized values, that is,
`wn/T`

.

`zgrid(`

plots a grid of constant damping factor and natural frequency lines for the damping
factors and natural frequencies in the vectors `zeta`

,`wn`

,`T`

)`zeta`

and
`wn`

, relative to sample time `T`

.
`zeta`

lines are independent for `T`

but the
`wn`

lines depend on the sample time value. Use this syntax to create
the z-plane grid with specific values of `wn`

.

`zgrid(___,'new')`

clears the current axes first and
sets `hold on`

.

`zgrid(`

plots the z-plane
grid on the `AX`

,___)`Axes`

or `UIAxes`

object in the current
figure with the handle `AX`

. Use this syntax when creating apps with
`zgrid`

in the App Designer.