ardized
                 periodic Schur form, that is, the general product
                 of the 2-by-2 triangular matrices corresponding to
                 a complex eigenvalue is diagonal.

  DEFL    CHARACTER*1
          Specifies the deflation strategy to be used, as follows:
          = 'C': apply a careful deflation strategy, that is,
                 the criteria are based on the magnitudes of
                 neighboring elements and infinite eigenvalues are
                 only deflated at the 