Scilab Function
Last update : 12/01/2004

armac - Scilab description of an armax process

### Calling Sequence

  `[ar]=armac(a,b,d,ny,nu,sig)`

### Parameters

- `a=[Id,a1,..,a_r]` : is a matrix of size (ny,r*ny)
- `b=[b0,.....,b_s]` : is a matrix of size (ny,(s+1)*nu)
- `d=[Id,d1,..,d_p]` : is a matrix of size (ny,p*ny);
- `ny`: dimension of the output y
- `nu`: dimension of the output u
- `sig`: a matrix of size (ny,ny)

### Description

This function creates a description as a tlist of an ARMAX process

`ar` is defined by

    ar=tlist(['ar','a','b','d','ny','nu','sig'],a,b,d,ny,nu,sig);

and thus the coefficients of `ar` can be retrieved by e.g. `ar('a')` .

### Examples

    a=[1,-2.851,2.717,-0.865].*.eye(2,2)
    b=[0,1,1,1].*.[1;1];
    d=[1,0.7,0.2].*.eye(2,2);
    sig=eye(2,2);
    ar=armac(a,b,d,2,1,sig)
    // extract polynomial matrices from ar representation
    [A,B,D]=arma2p(ar);

### See Also

`arma`, `armax`, `armax1`, `arsimul`, `arma2p`, `tlist`,