# wcsigmaplot

Plot worst-case gain of uncertain system

## Description

`wcsigmaplot(`

plots the nominal and
worst-case gains of the uncertain system `usys`

)`usys`

as a function of
frequency. For multi-input, multi-output (MIMO) systems, gain refers to the largest singular
value of the frequency response matrix. (See `sigma`

for more information about singular values.) The plot includes:

Nominal — Nominal gain of

`usys`

.Worst perturbation — The response falling within the uncertainty of

`usys`

that has the highest peak gain. This curve corresponds to the`wcu`

output argument of`wcgain`

.Worst-case gain (lower bound) — The lowest possible worst-case gain at each frequency.

Worst-case gain (upper bound) — The highest possible gain within the uncertainty at each frequency. This curve represents the envelope produced by finding the highest possible gain at each frequency.

Sampled Uncertainty — Responses randomly sampled from

`usys`

.

## Examples

## Input Arguments

## Algorithms

`wcsigmaplot`

uses `wcgain`

to compute the worst-case gains. Use the `opts`

argument to set options for the `wcgain`

algorithm.

`wcsigmaplot`

uses `usample`

to compute the `Sampled Uncertainty`

curves.

## Version History

**Introduced in R2016b**