rowregul removing poles and zeros at infinity

## Syntax

    [Stmp, Ws] = rowregul(Sl, alfa, beta)

## Arguments

Sl, Stmp

  `syslin` lists

alfa,beta

  real numbers (new pole and zero positions)

## Description

computes a postfilter `Ws` such that `Stmp=Ws*Sl` is proper and with full rank `D` matrix.

Poles at infinity of `Sl` are moved to `alfa`;

Zeros at infinity of `Sl` are moved to `beta`;

`Sl` is assumed to be a right invertible linear system (`syslin` list) in state-space representation with possibly a polynomial `D` matrix.

This function is the dual of colregul (see function code).

## Examples

    s=%s;
    w=[1/s,0;s/(s^3+2),2/s];
    Sl=tf2ss(w);
    [Stmp,Ws]=rowregul(Sl,-1,-2);
    Stmp('D')     // D matrix of Stmp
    clean(ss2tf(Stmp))

## See also

- invsyslin
- colregul