       On entry, the leading N/2-by-N/2 part of this array must
          contain the matrix B.
          On exit, if COMPQ = 'C', the leading N/2-by-N/2 part of
          this array contains the upper triangular matrix C1out
          (see METHOD); otherwise, it contains the upper triangular
          matrix C1 obtained just before the application of the
          periodic QZ algorithm.

  LDB     INTEGER
          The leading dimension of the array B.  LDB &gt;= MAX(1, N/2).

  FG      (input/output) DOUB