margin

Syntax

margin(sys)

margin(sys, tol)

[gm, pm, Wgm, Wpm] = margin(...)

Inputs

sys

A linear time-invariant transfer function or state-space system.

Type: class

tol

The tolerance below which small values are ignored (default: sqrt(eps)).

Type: double

Dimension: scalar

Outputs

gm

The gain margin as a ratio, not in decibels.

Type: double

Dimension: scalar

p

The phase margin in degrees.

Type: double

Dimension: scalar

Wgm

The frequency at which the gain margin is assessed, also known as the phase crossover.

The units are radians/sec for continuous systems, and Hz for discrete systems.

Type: double

Dimension: scalar

Wpm

The frequency at which the phase margin is assessed, also known as the gain crossover.

The units are radians/sec for continuous systems, and Hz for discrete systems.

Type: double

Dimension: scalar

Example

Create the bode plot with the margin information for the system below.

s = tf('s');
GH = 10000 / ((s+10)*(s+20)*(s+30));
margin(GH);

Figure 1. margin Example

Comments

If the output arguments are omitted, the bode plot is displayed with the margin information.