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See the recommended documentation of this function

# nlev

Leverrier's algorithm

### Calling Sequence

`[num,den]=nlev(A,z [,rmax])`

### Arguments

A

real square matrix

z

character string

rmax

optional parameter (see `bdiag`)

### Description

`[num,den]=nlev(A,z [,rmax])` computes `(z*eye()-A)^(-1)`

by block diagonalization of A followed by Leverrier's algorithm on each block.

This algorithm is better than the usual leverrier algorithm but still not perfect!

### Examples

```A=rand(3,3);x=poly(0,'x');
[NUM,den]=nlev(A,'x')
clean(den-poly(A,'x'))
clean(NUM/den-inv(x*eye()-A))```

• coff — resolvent (cofactor method)
• coffg — inverse of polynomial matrix
• glever — inverse of matrix pencil
• ss2tf — conversion from state-space to transfer function