Norm of linear model

`n = norm(sys)`

```
n =
norm(sys,2)
```

`n = norm(sys,Inf)`

```
[n,fpeak]
= norm(sys,Inf)
```

`[n,fpeak] = norm(sys,Inf,tol)`

or
`n`

= norm(`sys`

)

returns the root-mean-squares of the impulse response of the linear dynamic
system model `n`

=
norm(`sys`

,2)`sys`

. This value is equivalent to the *H*_{2} norm of
`sys`

.

returns the `n`

= norm(`sys`

,Inf)*L _{∞}* norm of

`sys`

, which is the peak gain of the frequency response
of `sys`

across frequencies. For MIMO systems, this quantity
is the peak gain over all frequencies and all input directions, which
corresponds to the peak value of the largest singular value of
`sys`

. For stable systems, the
`hinfnorm`

. After converting `sys`

to a state space model,
`norm`

uses the same algorithm as `covar`

for the *H*_{2} norm. For the
*L*_{∞} norm, `norm`

uses the algorithm of [1]. `norm`

computes the peak gain using the SLICOT library. For more
information about the SLICOT library, see http://slicot.org.

[1] Bruisma, N.A. and M. Steinbuch, "A Fast Algorithm to Compute
the H_{∞}-Norm of a Transfer Function Matrix,"
*System Control Letters*, 14 (1990), pp. 287-293.

`freqresp`

| `getPeakGain`

| `hinfnorm`

| `sigma`