 norm
  scaling transformation

               ( A''   G''  )    1  (   A   G/tau )
       H'' &lt;-- (          T ) = --- (           T ),             (3)
               ( Q''  -A''  )   tau ( tau Q   -A  )

  where tau is a real scalar.  Note that if tau is not equal to 1,
  then (3) is NOT a similarity transformation.  The eigenvalues
  of H are then tau times the eigenvalues of H''.

  For symplectic scaling (2), D is chosen to give the rows and
  columns of A' approximately equal 1-norms and to give Q'