# sgrid

s-plane grid lines.

### Syntax

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

### Arguments

- zeta
array of damping factors. Only values in

`[0 1]`

are taken into account. The default value is`[0 0.16 0.34 0.5 0.64 0.76 0.86 0.94 0.985 1]`

.- wn
array of natural frequencies in Hz. only positive values are taken into account. If not given it is computed by the program to fit with the boundaries of the plot.

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

### Description

Plots selected curves of constant damping ratio (selection given
by `zeta`

) and constant natural frequency
(selection given by `wn`

).

The `colors`

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

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

).

The `sgrid`

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

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

The optional argument `'new'`

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

### Examples

//sgrid clf();sgrid(0:0.2:1,[0.2 0.6 1 1.7 2])

## Comments

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