of NU and the number of
          Hankel singular values greater than MAX(TOL1,NS*EPS);
          NR can be further reduced to ensure that
          HSV(NR-NU) &gt; HSV(NR+1-NU).

  ALPHA   (input) DOUBLE PRECISION
          Specifies the ALPHA-stability boundary for the eigenvalues
          of the state dynamics matrix A. For a continuous-time
          system (DICO = 'C'), ALPHA &lt;= 0 is the boundary value for
          the real parts of eigenvalues, while for a discrete-time
          system (DICO = '