 ALPHA-stable eigenvalues of A and EPS is the machine
          precision (see LAPACK Library Routine DLAMCH).
          If ORDSEL = 'F', the value of TOL1 is ignored.
          TOL1 &lt; 1.

  TOL2    DOUBLE PRECISION
          The tolerance for determining the order of a minimal
          realization of the phase system (see METHOD) corresponding
          to the ALPHA-stable part of the given system.
          The recommended value is TOL2 = NS*EPS.
          This value is used by default if TOL2 &lt;= 0