# zgrid

zgrid plot

### Syntax

zgrid() zgrid(zeta,wn [,colors]) zgrid(['new',] zeta,wn [,colors]) zgrid(zeta,wn [,'new'] [,colors])

### Arguments

- zeta
array of damping factors. Only values in

`[0 1]`

are taken into account. The default value is`0:0.1:1`

.- wn
array of normalized natural frequencies (factors of π/dt). Only values in

`[0 1]`

are taken into account. The default value is`0:0.1:1`

.- colors
a scalar or an 2 element array with integer values (color index).

### Description

plots z-plane grid lines: lines of constant damping factor
(selection given by `zeta`

) and natural frequency
(selection given by `wn`

) are drawn in within the
unit Z-plane circle.

Iso-frequency curves are shown in on the interval [0,%pi/dt].

The `colors`

argument may be used to assign a
color for constant damping ratio curves
(`colors(2)`

) and for frequency curves
(`colors(1)`

).

The `zgrid`

function is often used to draw a grid
for evens root locus of continuous time linear systems. In such a
case the `zgrid`

function should be called after
the call to evans. For continuous time linear
systems one should use sgrid function instead.

The optional argument `'new'`

can be used to
erase the graphic window before plotting the grid.

### Examples

//zgrid clf();zgrid(0:0.2:1,[0.2 0.6 0.8 1])

## Comments

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