coff resolvent (cofactor method)

## Syntax

    [N,d]=coff(M [,var])

## Arguments

M

  square real matrix

var

  character string

N

  polynomial matrix (same size as `M`)

d

  polynomial (characteristic polynomial `poly(A,'s')`)

## Description

`coff` computes R=`(s*eye()-M)^-1` for `M` a real matrix. R is given by `N/d`.

`N` = numerator polynomial matrix.

`d` = common denominator.

`var` character string ('`s`' if omitted)

## Examples

    M=[1,2;0,3];
    [N,d]=coff(M)
    N/d
    inv(%s*eye(2,2)-M)

## See also

- coffg
- ss2tf
- nlev
- poly