# lncf

## Description

computes
the left normalized coprime factorization of the dynamic system model
`fact`

= lncf(`sys`

)`sys`

. The factorization is given by:

$$sys={M}_{l}^{-1}{N}_{l},\text{\hspace{1em}}{M}_{l}{M}_{l}^{*}+{N}_{l}{N}_{l}^{*}=I.$$

Here, $${M}_{l}^{*}$$ denotes the conjugate of *M _{l}* (see

`ctranspose`

). .
The returned model `fact`

is a minimal state-space realization of the
stable system
[*M*,

_{l}*N*]. This factorization is used in other normalized coprime factor computations such as model reduction (

_{l}`reducespec`

)
and controller synthesis (`ncfsyn`

).## Examples

## Input Arguments

## Output Arguments

## Tips

`fact`

is a minimal realization of`[Ml,Nl]`

. If you need to use`[Ml,Nl]`

or`[Ml,Nl]'`

in a computation, it is better to use`fact`

than to concatenate the factors yourself. Such manual concatenation results in extra (nonminimal) states, which can lead to decreased numerical accuracy.

## Version History

**Introduced in R2019a**

## See Also

`rncf`

| `reducespec`

| `ncfsyn`