sgrid

(Not recommended) Generate s-plane grid of constant damping factors and natural frequencies

sgrid is not recommended. To add an s-plane grid of constant damping factors and natural frequencies to a pole-zero plot of a continuous-time system, enable the AxesStyle.GridVisible property of the corresponding chart object instead. For more information, see Not recommended.

Syntax

sgrid

sgrid(zeta,wn)

sgrid(___,'new')

sgrid(AX,___)

Description

sgrid generates a grid of constant damping factors from 0 to 1 in steps of 0.1 and natural frequencies from 0 to 10 rad/sec in steps of one rad/sec for pole-zero and root locus plots. sgrid then plots the grid over the current axis. sgrid creates the grid over the plot if the current axis contains a continuous s-plane root locus diagram or pole-zero map.

sgrid(zeta,wn) plots a grid of constant damping factor and natural frequency lines for the damping factors and natural frequencies in the vectors zeta and wn, respectively. sgrid(zeta,wn) creates the grid over the plot if the current axis contains a continuous s-plane root locus diagram or pole-zero map.

Alternatively, you can select Grid from the context menu to generate the same s-plane grid.

sgrid(___,'new') clears the current axes first and sets hold on.

sgrid(AX,___) plots the s-plane grid on the Axes or UIAxes object in the current figure with the handle AX. Use this syntax when creating apps with sgrid in the App Designer.

Examples

Generate S-Plane Grid on Root Locus Plot

Create a continuous-time transfer function.

H = tf([2 5 1],[1 2 3]);

Plot the root locus of the transfer function.

rlocus(H)

Plot s-plane grid lines on the root locus.

sgrid

Input Arguments

zeta — Damping ratio

vector

Damping ratio, specified as a vector in the same order as wn.

wn — Normalized natural frequency

vector

Normalized natural frequency, specified as a vector.

AX — Object handle

Axes object | UIAxes object

Object handle, specified as an Axes or UIAxes object. Use AX to create apps with sgrid in the App Designer.

Version History

Introduced before R2006a

R2025a: Not recommended

sgrid is not recommended. To add an s-plane grid of constant damping factors and natural frequencies to a pole-zero plot of a continuous-time system, enable the AxesStyle.GridVisible property of the corresponding chart object instead. To configure the damping ratios and natural frequencies for the grid, use the AxesStyle.GridDampingSpec and AxesStyle.GridFrequencySpec properties, respectively.

You can also enable the default grid using the grid command.

This table shows some typical usages of sgrid and how to update your code to use chart object properties instead.

If your code has this form:	Use this code instead:
rlocus(sys); sgrid	rlocus(sys); grid
rlocusplot(sys); sgrid	rp = rlocusplot(sys); rp.AxesStyle.GridVisible = "on";
pzp = pzplot(sys); zeta = [0.2 0.4 0.6 0.8]; wn = [2 4]; sgrid(zeta,wn)	pzp = pzplot(sys); zeta = [0.2 0.4 0.6 0.8]; wn = [2 4]; pzp.AxesStyle.GridVisible = "on"; pzp.AxesStyle.GridDampingSpec = zeta; pzp.AxesStyle.GridFrequencySpec = wn;